Retatrutide, GLP-1s and the New Metabolic Era

In This Article

1. Foreword
2. Why the World Fell in Love with GLP-1 Drugs
3. What Is Retatrutide?
4. GLP-1, GIP and Glucagon Explained
5. The Willpower Question
6. The Reward Question
7. Obesity as a Signaling Disorder?
8. Leptin, Insulin and Information Overload
9. The Biological City
10. The GLP-1 Microscope
11. Fat Communicates
12. The Terrain Window
13. Muscle: Capacity vs Burden
14. Fasting, Autophagy and Signal Quieting
15. Structural Remodeling During the Window
16. Structure and Signals
17. Mitochondria, Inflammation and Biological Throughput
18. If You Never Use a GLP-1 Drug
19. Long-Term Questions
20. Key Insights
21. Final Reflection

Notes on Interpretation

Several sections of this article use systems-biology models, analogies and conceptual frameworks
(e.g. "The Biological City", "signal noise", "The Terrain Window").

These models are intended to help readers understand complex physiology.
They should be interpreted as explanatory frameworks rather than settled scientific mechanisms.

1. Foreword

For decades obesity was framed as a problem of willpower.

Eat less.

Move more.

Count calories.

Try harder.

The formula sounded simple.

Yet despite decades of advice, calorie counting, dietary guidelines, fitness programs and public health campaigns, obesity rates continued to rise across much of the developed world. [1, 2]

Something was not adding up.

Then a new class of drugs appeared, and the effects seemed to reach beyond the scale.

Food noise changed. Cravings changed. Reward itself seemed to change.

This raises an uncomfortable question:

Were we misunderstanding the problem?

If obesity were merely a matter of self-control, why would altering a handful of biological signals change behavior so broadly?

Why would appetite, reward, motivation and body weight all shift together?

The arrival of GLP-1 drugs may represent one of the most consequential developments in modern metabolic medicine. [3, 4, 5]

Not simply because they help people lose weight.

But because they may reveal how appetite, reward, metabolism and human behavior were connected all along.

The drug is not the story.

The drug reveals the story.

This article is written as a companion to The Great Fat Reversal.

That article focused on biological structure: how dietary fats become membranes, how membrane composition influences resilience, and why oxidation can propagate through lipid environments like fire through a dry forest.

This matters because membranes are not abstract biology. They are fat-rich surfaces that surround cells, shape mitochondria, hold receptors and help determine how signals are received.

This article begins where that one ended, because signals do not move through an abstract body.

They move through structure.

If structure influences signaling, then changes in biological structure may influence how signals are received, interpreted and acted upon.

The story now shifts from structure to signals.

2. Why the World Fell in Love with GLP-1 Drugs

The popularity of GLP-1 drugs did not emerge in a vacuum. They arrived after decades of frustration, relapse and sincere effort.

Many people found themselves trapped in a familiar cycle:

Lose weight.

Regain weight.

Try again.

Repeat.

Over time, a growing number of researchers began asking whether obesity involved more hidden biology than the public conversation allowed.

The trial results were difficult to ignore. Weight loss was often substantial. Blood sugar regulation improved. Markers of metabolic health improved. [3, 4, 5]

Yet many users reported something even more surprising: the experience of appetite itself seemed to change. [10, 11] Some studies and user reports also suggest possible changes in alcohol consumption and other reward-related behaviors, though the evidence remains early and continues to evolve. [12, 13, 42]

This was not what many people expected. Here was a class of drugs producing changes that seemed to reach beyond appetite alone.

This forced a deeper question:

Were these drugs solving a problem?

Or were they revealing a problem that had existed all along?

3. What Is Retatrutide?

Retatrutide belongs to a newer generation of metabolic drugs designed to interact with the body's own signaling systems. Unlike many older weight-loss approaches, it does not work primarily by increasing stimulant activity or forcing the body into a state of artificial stress. Instead, it appears to influence several biological signals involved in appetite, metabolism and energy regulation. [5]

What makes retatrutide particularly interesting is that it acts on three separate pathways simultaneously: [5, 8, 9, 38]

• GLP-1 (Glucagon-Like Peptide-1)
• GIP (Glucose-Dependent Insulinotropic Polypeptide)
• Glucagon

For this reason, retatrutide is often referred to as a triple agonist.

The details can become highly technical. Fortunately, the core idea is simple: the drug works through the body's own information systems.

The body is not a collection of isolated parts. It is a communication network.

Retatrutide appears to alter part of that conversation.

This is important because many discussions about obesity focus almost entirely on calories. Yet calories are only part of the story. Before food becomes energy, it first becomes information.

The body must decide:

• Are we hungry?
• Are we full?
• Should we store energy?
• Should we release energy?
• Should we seek more food?
• Is this reward worth pursuing?

These decisions are regulated through signals. Retatrutide appears to modify several of those signals simultaneously. That is why its effects may extend beyond simple appetite suppression.

4. GLP-1, GIP and Glucagon Explained

The three pathways are worth separating because each contributes a different part of the metabolic conversation:

• Have we eaten?
• Do we need more food?
• Should we store energy?
• Should we release energy?
• How urgently should we seek reward?

These are not merely metabolic questions.

They are behavioral questions.

Together, they help explain why a single drug can appear to affect appetite, metabolism and behavior at the same time.

GLP-1: The Satiety Messenger

GLP-1 is released after eating. One of its jobs is to communicate that food has arrived. It helps slow stomach emptying, promotes satiety and influences appetite regulation. [7, 8, 9]

In simple terms, GLP-1 helps the body recognize:

We have received nourishment.

Perhaps more interestingly, GLP-1 receptors are found not only in the digestive system, but also in regions of the brain involved in appetite and reward. [10, 14] This is an important clue. It suggests that eating behavior is not regulated by the stomach alone. The brain is part of the conversation.

GLP-1 does not simply influence digestion.

It helps influence how food is experienced.

GIP: The Nutrient Coordinator

GIP is another hormone released after eating. Historically it received less attention than GLP-1, but newer therapies have renewed scientific interest in its role. GIP helps coordinate how the body responds to incoming nutrients and participates in the regulation of insulin secretion. [8, 9]

Scientists are still refining their understanding of exactly how GIP contributes to appetite, metabolism and body composition. What is clear is that it appears to be an important part of the body's nutrient-management network.

Retatrutide engages this pathway as well. [5]

Glucagon: The Energy Mobilizer

Most people have heard of insulin. Far fewer have heard of glucagon. If insulin is associated with storing and managing incoming energy, glucagon is often associated with mobilizing stored energy when needed.

Glucagon helps the body access energy reserves. In simple terms, it helps ensure that stored fuel remains available when circumstances require it. [38]

This makes retatrutide unusual. Rather than influencing a single pathway, it appears to influence satiety, nutrient handling and energy mobilization simultaneously. The result is a much broader effect on metabolic regulation than many earlier approaches. [5]

More Than Calories

This is the point of walking through GLP-1, GIP and glucagon together.

The question is not whether calories matter. They do.

The question is how the body decides whether incoming energy should be desired, stored, burned or mobilized.

Notice what has been missing from this discussion.

Willpower.

None of these signals care about motivational speeches.

They are biological communication systems.

The body is constantly making decisions about hunger, satiety, energy storage and energy expenditure based on incoming information.

5. The Willpower Question

The discipline model had one obvious strength: it sounded straightforward. People gain weight because they consume more energy than they expend. Therefore, the solution is simple:

Eat less.

Move more.

On one level, this is undeniably true. Energy cannot be created from nothing. Calories matter. Energy balance matters. The laws of physics have not been suspended. [15, 40]

Yet something about this explanation feels incomplete. If conscious discipline were the main lever, why would altering biological signals change appetite, cravings, reward-seeking and food preoccupation at the same time?

The success of GLP-1 drugs does not invalidate thermodynamics. What it challenges is the assumption that human beings consciously control every variable influencing thermodynamics.

Biology participates. Signals participate. Hormones participate. The brain participates. Reward systems participate.

In other words:

The body is not merely counting calories.

The body is interpreting information about calories.

This distinction matters.

A person experiencing intense hunger is not operating under the same biological conditions as a person experiencing satiety. A person constantly preoccupied with food is not operating under the same conditions as a person whose appetite signals are calm and regulated.

The question is no longer:

Do calories matter?

The question becomes:

What determines how calories are handled?

And that question leads directly into one of the most fascinating discoveries of the GLP-1 era.

The reward question. [14, 15]

6. The Reward Question

Something unexpected happened when GLP-1 drugs entered widespread use. People did not merely report eating less. Many reported wanting less.

The distinction is important.

Eating less because you are forcing yourself to resist temptation is one experience. Eating less because the temptation itself has diminished is a very different experience.

Some reported something even stranger: a reduced interest in alcohol. [12] Anecdotal reports have described changes in shopping habits, impulsive behaviors and other reward-related behaviors, although these effects remain much less established than changes in appetite and food intake.

Not everyone experienced these effects. But the pattern became common enough that researchers began paying attention.

This raises an intriguing question:

Why would a drug originally developed for metabolic regulation appear to influence behavior?

The answer may lie in a simple fact that many people never consider. Eating is not merely a metabolic activity. It is a reward activity. [13, 42]

The brain is not only asking:

Do we need calories?

It is also asking:

Is this worth pursuing?

Throughout evolution, food represented survival. Finding food was rewarding because finding food increased the chances of staying alive. The reward system evolved for a reason: it motivates behavior, encourages action and helps organisms pursue things that matter.

The modern world, however, presents a challenge that our ancestors rarely faced. Reward is everywhere. Food is everywhere. Stimulation is everywhere. Temptation is everywhere.

Many people spend their entire day surrounded by signals competing for attention.

Notifications. Emails. Social media. Advertising. Ultra-processed food. Artificial lighting. Stress. Constant eating. Entertainment.

Modern humans live inside a constant signal storm.

The signal environment rarely gets quiet.

In that environment, it becomes difficult to separate hunger from habit.

Need from desire.

Satiety from stimulation.

The emerging GLP-1 story suggests something fascinating.

These pathways may influence not only hunger, but also how reward itself is experienced. [10, 13] This does not mean reward is bad. Reward is essential. The question is whether modern reward systems are exposed to patterns of stimulation that can make regulation more difficult.

And if so, what happens when some of that noise is reduced?

The answer may help explain why so many users describe the same experience:

The internal noise becomes quieter.

And for the first time in a long time, meaningful signals become easier to hear.

7. Obesity as a Signaling Disorder?

The phrase may sound strange at first. Most discussions about obesity focus on storage: too much fat, too many calories, too little exercise, too much food.

But what if obesity also involves communication?

The body is constantly exchanging information. The gut talks to the brain. The brain talks to the pancreas. The pancreas talks to the liver. Fat tissue talks to nearly everything. [14, 16, 19]

At every moment, billions of cells are sending and receiving signals.

These signals help answer questions such as:

• Are we hungry?
• Are we full?
• Should we store energy?
• Should we release energy?
• Do we need more food?
• Is this reward worth pursuing?

The body is not merely managing fuel.

It is managing information.

This distinction becomes important when we examine what happens in obesity. Many individuals with obesity do not appear to suffer from a shortage of energy. In fact, they often possess substantial stored energy reserves. Yet stored energy does not automatically translate into calm appetite, easy access to fuel or clear regulation. [16, 17, 23]

This suggests that the challenge may involve more than energy alone.

It may involve signaling.

The success of GLP-1 drugs does not prove that obesity is purely a signaling disorder. Nor does it invalidate the importance of calories. What it does suggest is that communication systems play a larger role than many people previously assumed.

And once we begin looking at obesity through the lens of communication, several fascinating observations begin to make sense.

One of the most important involves a hormone called leptin.

8. Leptin, Insulin and Information Overload

If GLP-1 introduced us to the importance of signaling, leptin forces us to ask a deeper question:

What happens when signals stop working?

Leptin is a hormone produced primarily by fat tissue. Its job appears deceptively simple: it helps communicate information about the body's stored energy reserves. [16]

In very simple terms, leptin helps send a message that says:

We have fuel available.

At first glance, the system appears elegant. More body fat generally produces more leptin. More leptin should signal that energy stores are abundant. Appetite should decrease. Food seeking should become less urgent.

Yet obesity researchers encountered a puzzle. Many individuals with obesity possess not only large energy reserves, but also elevated leptin levels. In other words, the signal exists. Yet hunger often persists, cravings often persist and food preoccupation often persists. [16, 17]

This observation helped give rise to the concept of leptin resistance.

The exact mechanisms remain an active area of research, but the broader systems perspective is fascinating.

The issue may not be the absence of stored energy.
Nor may it be the absence of a signal announcing that stored energy exists.

The harder question is whether the system can respond to that information effectively.

This distinction matters:

Stored energy is not the same as accessible energy.

To use stored fat, the body must be able to mobilize it, transport it, oxidize it and move the resulting energy through mitochondrial systems without excessive congestion. That requires metabolic flexibility. It requires beta-oxidation capacity. It requires tissues that can switch between incoming fuel and stored fuel without distress. [23, 29, 45]

In other words:

Leptin may help report the reserve.

Metabolic flexibility determines whether that reserve can become usable flow.

The signal exists, but downstream tissues and neural circuits may respond differently under chronic metabolic stress. And if the machinery for accessing stored fuel has become underused, the signal may not translate cleanly into calm appetite, stable energy or easy fat oxidation.

Imagine a smoke alarm. If it sounds once, everyone pays attention. If it sounds every minute for years, people eventually stop responding. Not because the alarm disappeared, but because constant signaling erodes informational value.

The signal becomes noise.

The same systems perspective may help us think about insulin resistance.

Insulin is one of the body's primary energy-management signals. After meals, insulin helps coordinate how nutrients are processed and stored. [18]

But what happens when energy arrives constantly?

Breakfast. Snacks. Sugary drinks. Lunch. Snacks. Dinner. Dessert.

Day after day. Year after year.

The body receives the same message repeatedly:

Energy is arriving.

From a systems perspective, adaptation becomes unsurprising. Biological systems are designed to respond to information. They are not necessarily designed to receive the same message continuously without consequence.

This leads to a powerful possibility.

Biological systems do not merely become dysregulated through structural damage. They can also become dysregulated when signaling patterns are chronic, distorted or poorly matched to the environment.

Modern humans live inside a constant signal storm: food signals, reward signals, advertising signals, stress signals, light signals and notification signals.

The signal environment never fully quiets.

Leptin resistance and insulin resistance may represent different manifestations of the same broader challenge:

How does a communication system maintain signal quality when stimulation becomes chronic?

This question will become increasingly important as we continue exploring obesity, reward regulation and the biology of modern life.

9. The Biological City

Imagine a small, well-functioning city. Traffic flows smoothly. Emergency services respond efficiently. Communication systems work. Power plants meet demand. Important messages reach their destinations. The city is busy, but it remains organized.

Now imagine that same city after decades of unchecked growth. Traffic increases. Roads become congested. Emergency services become overwhelmed. Power demand rises. Communication networks become noisy. Alarms sound constantly. Every department is working harder than before.

The city still functions, but efficiency begins to decline. Important messages become harder to distinguish from background noise.

This analogy provides a useful way to think about biological systems.

The human body is not a collection of isolated organs.

It is a city.

The brain, gut, liver, pancreas, muscles and fat tissue are all communicating simultaneously.

Hormones function like messages. Receptors function like receivers. Nerves function like communication lines. Blood vessels function like transportation networks.

The body depends upon information moving efficiently between systems. When communication remains clear, regulation becomes easier. When communication becomes distorted, regulation becomes more difficult.

This perspective offers one way to understand why obesity, insulin resistance, reward dysregulation and chronic inflammation often appear together. They are not always separate problems. In some cases, they may represent interacting manifestations of a regulatory network operating under increasing strain. [18, 20, 21, 22, 34, 35]

The challenge is not necessarily the absence of signals. The challenge may be maintaining signal quality within an increasingly noisy environment.

This is why the concept of information overload becomes so interesting.

The issue is not that messages stop being sent. The issue is that meaningful messages become harder to hear.

The city is still communicating.

The city is simply becoming louder.

And once a communication system becomes noisy enough, even important signals can begin to lose their effectiveness.

The question then becomes:

How do we restore clarity?

The answer may help explain not only the success of GLP-1 drugs, but many other interventions as well.

Sleep. Fasting. Exercise. Stress reduction. Improved food quality. [25, 26, 27, 36, 43]

Each may, in different ways, improve metabolic, inflammatory or neuroendocrine regulation.

The city functions best when it occasionally becomes quiet.

The city needs to sleep.

10. The GLP-1 Microscope

Most discussions about GLP-1 drugs focus on outcomes: weight loss, blood sugar control, reduced appetite and improved metabolic health. These outcomes matter, but they also reveal something deeper about appetite regulation itself. [3, 4, 5]

This is where the microscope analogy becomes useful.

A microscope does not create biology. It reveals biology. It allows us to observe relationships that were previously difficult to see.

GLP-1 drugs may be doing something similar. By altering a handful of key signals, they make relationships between metabolism, reward, behavior and physiology easier to observe. [10, 11, 13, 14]

For decades, obesity was often discussed primarily as a storage problem: too much energy, too much fat, too many calories.

The GLP-1 era invites a broader perspective. What if obesity also involves:

• signal quality
• reward regulation
• appetite regulation
• information processing
• metabolic communication

The remarkable thing is not that people lose weight. The remarkable thing is that altering a few signaling pathways can change so many aspects of behavior simultaneously.

Cravings change. Food preoccupation changes. Reward-seeking changes. Meal patterns change. Decision-making changes.

This should make us pause, because it suggests that many behaviors we considered independent may have been connected through underlying biological networks.

The drug becomes a clue.

A probe.

A microscope.

The question is no longer:

How does the drug force weight loss?

The question becomes:

What was the drug revealing about the system all along?

The more we understand these underlying signals, the more we begin to understand the system that produced the obesity epidemic in the first place.

And that system leads us directly to one of the most surprising discoveries in modern metabolism.

Fat tissue is not silent.

It is constantly communicating.

11. Fat Communicates

For decades fat tissue was viewed primarily as storage. Excess calories arrived. Fat stored them. End of story.

Modern physiology paints a very different picture.

Fat is not merely storage.

Fat is an endocrine organ. [19]

It communicates continuously with the rest of the body through hormones, adipokines, cytokines and metabolic signals. [19, 20]

In other words:

Fat talks.

This realization changes how we think about obesity.

Most people imagine something like this:

Fat cell receives fat.

Fat cell happy.

End of story.

Reality appears more complicated. Like people, fat cells do not seem particularly enthusiastic about unlimited expansion. As fat depots enlarge, oxygen delivery becomes more difficult, cellular stress rises, immune cells begin arriving, and signaling patterns start to change. [20, 21, 22]

The tissue becomes increasingly active. Inflammatory signaling rises. Distress signals rise.

The conversation changes.

Healthy fat whispers.

Angry fat shouts.

Fat tissue is constantly communicating with the rest of the body. Leptin, adipokines, cytokines and immune cells are all part of that communication.

The body is not merely storing energy. It is discussing energy.

This helps explain why obesity is often associated with chronic inflammation. [20, 21, 22]

The tissue is not silent.

The tissue is broadcasting.

From a systems perspective, obesity may not simply represent excess storage. It may be interpreted as a sign that regulatory capacity has been exceeded.

Fat cells do not like becoming huge. And when biological systems become stressed, they tend to communicate more loudly.

This idea will become even more important when we begin exploring the Terrain Window and the process of restoring signal clarity.

12. The Terrain Window

Most discussions about GLP-1 drugs focus on weight loss. The Codex views the situation somewhat differently. Weight loss is important, but one of the most valuable parts of the process may be the window it can create.

A quieter city. A clearer signal. A period where behavior, nutrition and training may become easier to steer.

This is the Terrain Window.

The period during which:

• appetite is reduced
• food noise is reduced
• cravings are reduced
• body weight is declining
• inflammation may be decreasing [37]
• metabolic flexibility may be improving

For many people, this may be the first time in years that biological signals become easier to hear. Like many biological adaptations, metabolic flexibility often improves with practice. [23]

That matters because the goal is not only to notice stored energy. The goal is to regain the ability to use it.

Stored fuel becomes useful only when the body can access it, burn it and move the resulting energy through the system. This is where beta-oxidation, mitochondrial throughput and muscle demand become part of the same story. [23, 24, 29]

The mistake would be to view this window as merely a period for losing weight. The larger opportunity is rebuilding, which the later remodeling section explores in more detail.

The question becomes:

What should be rebuilt while the city is quiet?

This may be a useful time to:

• improve food quality
• increase protein intake
• build muscle
• improve sleep
• increase physical activity
• restore metabolic flexibility
• reduce ultra-processed foods
• address nutrient deficiencies
• support mitochondrial function
• reduce toxic burden where appropriate

In other words:

Use the window to improve the terrain.

The body is constantly rebuilding itself. The question is not whether rebuilding is occurring. The question is what conditions exist while rebuilding occurs. [41]

This is where the opportunity becomes interesting. The drug may reduce noise, but the biological materials still come from somewhere. The structures still come from somewhere. The terrain still matters.

The city becoming quiet is not the destination. It is the opening.

13. Muscle: Capacity vs Burden

Most discussions about weight loss focus on what is being removed: less body fat, less body weight, smaller clothing sizes, lower numbers on the scale. These changes can be valuable.

But they only tell half the story.

The other half involves what is being built.

The human body is not merely a storage system. It is also an energy-throughput system.

Muscle represents capacity.

Fat represents stored energy.

Both have biological roles.

And both are communicating.

If fat talks about storage and stress, muscle talks about demand and capacity.

Fat says things like:

• "We have enough stored energy."
• "Storage is getting crowded."
• "This tissue is inflamed."
• "Signals are noisy."

Muscle says something different:

• "There is somewhere useful for fuel to go."
• "We can clear glucose."
• "We can burn energy."
• "We need repair, protein, mitochondria and blood flow."
• "Preserve me. Build capacity, not just smaller size."

The question is whether the balance between them supports health and resilience.

This perspective becomes particularly useful when considering the Terrain Window. As excess body fat decreases, one form of burden may decrease with it. At the same time, muscle can be built.

This changes the equation.

Fat loss reduces burden.

Muscle building increases capacity.

Together, they change the conversation.

These are not identical processes. One removes strain. The other increases the body's ability to move energy through the system without backing up.

From a systems perspective, this distinction matters.

Muscle tissue is metabolically active. It participates in glucose regulation and energy utilization. It gives incoming fuel somewhere useful to go. [24, 25]

But the deeper point is mitochondrial.

Working muscle creates demand. Demand pulls energy forward. When muscle is trained and active, mitochondria are not merely asked to produce energy; they are given a reason to improve throughput. [24, 25, 29]

More useful demand can mean:

• better glucose disposal
• more mitochondrial machinery
• stronger fuel switching
• smoother electron flow
• less tendency for energy input to become congestion

This is why muscle is not just a cosmetic concern during weight loss.

That helps explain why many researchers increasingly emphasize preserving or building muscle during weight loss.

The goal is not simply becoming lighter.

The goal is becoming more capable of handling energy.

This idea also connects to the biological city.

Imagine a city carrying an increasing maintenance burden: more traffic, more congestion, more demand, more strain.

Now imagine reducing some of that burden while simultaneously upgrading infrastructure: more roads, better traffic flow, stronger power stations, fewer bottlenecks.

That is a very different outcome than merely reducing size.

The same principle may apply biologically. Successful metabolic recovery is not only about removing what was excessive. It is also about strengthening what was missing.

This is one reason resistance training deserves special attention during the Terrain Window. The opportunity is not merely to lose weight. The opportunity is to rebuild capacity. [25]

And as capacity rises, another fascinating phenomenon often begins to reappear.

Metabolic flexibility. [23]

14. Fasting, Autophagy and Signal Quieting

One of the most interesting themes to emerge from modern metabolic research is the idea that biological systems occasionally benefit from periods of reduced input.

This principle appears repeatedly throughout nature. Forests recover after disturbances. Cities perform maintenance during quiet hours. Road repairs occur when traffic decreases. The body appears to operate similarly.

Much of modern life is characterized by continuous stimulation. Food is available everywhere. Reward is available everywhere. Information is available everywhere.

The biological city rarely becomes quiet.

Yet many biological maintenance systems appear to function best when incoming demands temporarily decrease. This helps explain the growing interest in fasting. Fasting is often discussed as a weight-loss strategy, but from a systems perspective, its most interesting effects may extend beyond body weight alone. [26, 27]

During periods without food, several things begin to change. Insulin levels generally fall. Stored energy begins contributing more significantly to fuel requirements. The body becomes increasingly dependent on its ability to access internal reserves. [23, 26, 27]

This process is closely linked to metabolic flexibility.

The ability to transition between incoming fuel and stored fuel.

Many people spend years operating primarily in a fed state: breakfast, snacks, lunch, snacks, dinner, dessert.

Fasting temporarily changes the conversation.

Some of the constant signaling begins to diminish. The body receives fewer incoming messages about nutrient arrival.

This point is worth emphasizing. Many people rarely experience extended periods without incoming calories. A typical modern pattern may involve breakfast, snacks, lunch, snacks, dinner and evening eating. Incoming nutrient traffic can become nearly continuous.

As a result, many people spend surprisingly little time relying primarily on stored energy.

Intermittent fasting exists on a spectrum. A 12-hour overnight fast is very different from a 16-hour fast. A 16-hour fast is different from an 18- or 24-hour fast. The exact timing varies between individuals, but longer fasting periods generally create stronger conditions for fuel switching and cellular maintenance processes.

For many people, even reaching 16–18 hours without food can feel surprisingly difficult at first.

That observation may offer a useful clue about modern eating patterns and metabolic flexibility.

For some individuals, this appears to improve awareness of hunger and satiety signals that may have been obscured by constant stimulation.

Another concept frequently associated with fasting is autophagy. Autophagy is often described as a cellular recycling process. Damaged components can be broken down, useful materials can be recovered and cellular housekeeping can occur. [27, 28]

Importantly, autophagy is not an on-off switch that suddenly activates at a precise hour. It appears to operate continuously at varying levels and is influenced by many factors. However, longer periods without food generally create stronger conditions for maintenance and recycling processes. [27, 28]

This is one reason fasting continues to attract scientific interest.

Many researchers suspect that modern humans may spend less time in these lower-input metabolic states than our physiology evolved to expect. The scientific details are complex, but the broader principle is intuitive.

When incoming demands decrease, maintenance becomes easier.

A city constantly flooded with traffic struggles to repair roads. A city with occasional quiet periods can perform maintenance. The same principle may apply biologically.

This does not mean fasting is required. Nor does it mean everyone should fast. The important lesson is broader.

Many biological systems appear to benefit from periods of reduced input and recovery.

This observation may help explain why so many seemingly different interventions often point in the same direction:

• fasting
• improved sleep
• reduced ultra-processed foods
• stress reduction
• exercise
• GLP-1 therapy

All may help create conditions where regulation improves and meaningful signals become easier to interpret.

Maintenance needs quiet.

When input falls, something remarkable can happen. The body can finally devote more attention to rebuilding.

A surprising number of people perform regular maintenance on their cars while rarely allowing their metabolism similar opportunities for maintenance and repair.

15. Structural Remodeling During the Window

One of the most overlooked aspects of health is that the body is constantly rebuilding itself. This process never stops. Proteins are replaced. Cellular components are repaired. Membranes are remodeled. Mitochondria undergo maintenance. Tissues adapt to changing conditions. [29, 30, 41]

Millions upon millions of biological repair and remodeling events occur every day.

The question is not whether rebuilding is happening. The question is what conditions exist while rebuilding occurs.

This is where the Terrain Window becomes particularly interesting.

If appetite decreases, if food quality improves, if inflammation decreases, if sleep improves, if metabolic flexibility improves.

Then those same repair processes are occurring under different conditions than before. The significance of this idea is easy to underestimate.

People often expect immediate transformation. A week passes. A month passes.

They ask:

Where is my result?

But structural biology is not TikTok.

The body remodels itself gradually. One repair event at a time. One membrane at a time. One protein at a time. One mitochondrion at a time.

Meaningful change often emerges from the accumulation of countless small improvements.

This idea also helps explain why consistency matters. A healthier environment maintained for months may influence millions of repair and replacement events. Eventually those changes begin to accumulate. [41]

The city becomes different because the infrastructure becomes different.

This is where the previous article, The Great Fat Reversal, becomes relevant again.

That article explored a simple but powerful idea:

The fats you eat become part of your structure.

Structure affects function.

Structure affects resilience.

And, as we increasingly discover, structure affects signaling.

The body is not rebuilt from intentions. It is rebuilt from materials. [24, 30, 41]

That matters here because the Terrain Window is not only a period of weight change. It may also be a period when tissues are being remodeled, repaired and re-supplied with new structural inputs.

The Terrain Window may provide an opportunity to improve both the signals directing repair and the materials being used for repair.

When viewed through this lens, weight loss becomes only one part of the story. The deeper story is remodeling.

Related: The Great Fat Reversal

16. Structure and Signals

Throughout this article, two themes have appeared repeatedly.

Structure.

Signals.

At first they may seem like separate subjects. They are not. They are deeply intertwined.

The body is built from structures: membranes, proteins, mitochondria, organs and tissues.

Membranes deserve special attention because they are built largely from lipids. In plain language, the fats that enter the body can become part of the surfaces around cells, inside cells and around mitochondria. These surfaces are not passive wrappers. They help organize receptors, channels and enzymes that allow cells to sense and respond to the world around them. [30, 31]

A membrane is less like plastic wrap and more like a living control surface.

Yet these structures do not merely exist. They communicate. Signals move through them. Signals depend upon them.

This leads to an important realization:

Structure affects signals.

Signals affect structure.

The relationship works in both directions. This idea helps connect many of the themes explored throughout the Codex.

The fats you eat become part of your biological structure. Membranes help determine how signals are received and processed. When membrane structure is resilient, communication may be easier to maintain. When membrane structure is damaged, oxidized or poorly maintained, signal management may become harder. Mitochondria influence energy production. Energy production influences signaling. Signaling influences behavior. Behavior influences food choices. Food choices influence structure.

The loop closes.

Consider a simple example.

A membrane is not merely a barrier. It is also a communication platform. Receptors sit within membranes. Signals interact with membranes. Information moves through membranes. Cell membranes, mitochondrial membranes and internal cellular membranes all participate in this larger architecture of communication.

Changes in structure can therefore influence how communication occurs.

Likewise, signals influence structure. Hormones influence appetite. Appetite influences food choices. Food choices influence body composition. Body composition influences signaling.

Again, the loop closes.

This is why biology is often difficult to reduce to simple cause-and-effect explanations. The body is not a chain. It is a network. [34, 35]

Feedback loops exist everywhere: good loops, bad loops, self-reinforcing loops and corrective loops.

This perspective also helps explain why meaningful change can sometimes appear slow at first and then accelerate. Small improvements in structure may improve signaling. Improved signaling may improve behavior. Improved behavior may further improve structure.

The loop begins working in a different direction.

The same principle applies in reverse. Poor structure may impair signaling. Impaired signaling may encourage behaviors that further degrade structure.

Again, the loop closes.

This is one reason systems biology is so fascinating. The question is rarely:

What caused this?

The deeper question is often:

What loops are currently reinforcing it?

The significance of GLP-1 drugs may lie partly in their ability to interrupt some of these loops. The significance of nutrition may lie partly in its ability to influence the structures participating in those loops. The significance of sleep, exercise and fasting may lie partly in their ability to improve communication within those loops. [10, 30, 36, 43]

Viewed through this lens, health becomes less about isolated interventions and more about restoring constructive feedback. The body is built from feedback loops.

And understanding those loops may be one of the most important keys to understanding human biology.

For readers who want the structural side of this loop, The Great Fat Reversal explores membranes, lipid composition and oxidation.

For readers who want the energy side, the mitochondrial articles explain how those structures support ATP production, redox balance and adaptation.

Related Codex articles:

• The Great Fat Reversal
• Gate 5 - Mitochondria and Energy Production
• Advanced Mitochondria

17. Mitochondria, Inflammation and Biological Throughput

Throughout this article we have discussed signals: leptin, insulin, GLP-1, reward pathways and communication networks.

But communication alone does not explain biology. Every message must ultimately be powered, interpreted and acted upon. That is why mitochondrial capacity becomes part of the story.

This brings us to the mitochondria. Often described as the power plants of the cell, mitochondria convert nutrients into usable biological energy. Nearly every process discussed in this article depends upon their activity. [29, 44]

Repair requires energy. Movement requires energy. Immune regulation requires energy. Protein synthesis requires energy. Signal transmission requires energy.

Everything costs ATP.

This perspective reveals something interesting about obesity. Most people think of obesity primarily as excess stored energy, and that is partly true. But obesity can also be viewed as increased biological throughput. [15, 29]

A larger system requires more maintenance: more tissue, more signaling, more circulation, more regulation, more repair.

As the city becomes larger, it generally requires more infrastructure to keep functioning smoothly.

This does not mean obesity automatically causes mitochondrial dysfunction, nor does it mean every individual experiences the same challenges. However, greater body mass and metabolic load can place greater demands on the systems responsible for energy production and maintenance. [15, 29, 45]

Every day, mitochondria must meet those demands. And wherever energy production occurs, oxidative stress tends to appear. [29]

Oxidative stress is not inherently bad. It is a natural consequence of energy production. Life requires controlled oxidation.

The challenge is not generating reactive species.

The challenge is containing them.

This is where the forest analogy from The Great Fat Reversal becomes useful.

A healthy forest can tolerate occasional sparks. Small disturbances occur. Damage is repaired. Order is restored.

Problems arise when conditions become increasingly vulnerable to propagation. The spark is no longer the issue. The issue becomes what the spark encounters.

The same systems perspective can be applied to biology.

More throughput generally means:

• more electron flow
• more reactive oxygen species generation
• more repair demand

The body is designed to manage these challenges. But as throughput rises, the demands placed upon repair systems rise as well.

This is one reason the Terrain Window may be so valuable. Reducing excess burden does not merely change body weight. It may reduce the amount of biological traffic moving through the system.

The city becomes easier to manage. Maintenance becomes easier to perform. Signals become easier to interpret. Repair becomes easier to complete.

This idea becomes especially interesting when we remember that some of the most important biological structures sit directly beside intense energy production. This is where the connection to The Great Fat Reversal becomes practical rather than decorative.

Consider cardiolipin.

Cardiolipin is a specialized phospholipid found within the inner mitochondrial membrane. It plays a critical role in the organization and function of the electron transport chain. In simple terms, it helps support the machinery responsible for producing ATP. [29, 30, 44]

The important point is not merely that cardiolipin exists. The important point is where it sits and what it is asked to do. It is part of the membrane architecture surrounding the machinery of energy production.

This makes cardiolipin fascinating. Not because it is dangerous. Because it is essential. But like many essential structures, its importance also makes its quality and resilience matter.

Yet it sits directly beside:

• intense electron flow
• reactive oxygen species generation
• ATP production

In other words, one of the most important membrane structures in human biology operates immediately adjacent to one of the most metabolically active environments in the body. In The Great Fat Reversal, this was described as a vulnerable lipid structure sitting beside the biological combustion engine. The point was not that cardiolipin is a villain. The point was that membrane composition, oxidative pressure and repair capacity all matter more when the surrounding environment is metabolically intense.

This observation does not prove that any single dietary factor explains modern disease. Biology is rarely that simple. But it does reinforce a broader lesson.

Structure matters.

The architecture supporting energy production matters.

The materials used to build that architecture matter.

And the demands placed upon that architecture matter.

Viewed through this lens, obesity becomes more than a storage problem. It becomes a throughput problem. An infrastructure problem. A signaling problem. A maintenance problem.

And perhaps most importantly, a systems problem.

Related Codex articles:

• The Great Fat Reversal
• Gate 5 - Mitochondria and Energy Production
• Advanced Mitochondria
• Metabolic Flexibility

18. If You Never Use a GLP-1 Drug

Many readers will never use a GLP-1 drug. Some will be unable to access them. Some will be concerned about cost. Some will prefer non-pharmaceutical approaches. Others may simply decide the tradeoffs are not worth it.

These are reasonable positions.

The most important lessons of this article do not depend upon taking a drug.

The deeper lesson is that obesity, appetite and reward appear to be influenced by biological signals far more than many people once assumed.

GLP-1 drugs did not create those signals. They revealed them.

The same themes appear throughout many non-pharmaceutical interventions:

• improved sleep
• resistance training
• fasting
• metabolic flexibility
• improved food quality
• reduced ultra-processed foods
• stress reduction

Different interventions may operate through different mechanisms. Fasting, sleep, resistance training and nutrition do not work through identical pathways. But each can help change the conditions under which metabolism, repair and behavior are regulated. [24, 25, 26, 27, 36, 43]

Different paths.

Similar destination.

None of these approaches exactly replicate GLP-1 drugs. Nor should they be expected to. The point is not imitation. The point is understanding.

The drug is one tool. Biology is the larger story.

And once the story becomes visible, the lessons remain valuable whether a person uses the drug or not.

19. Long-Term Questions

Despite the excitement surrounding GLP-1 drugs, many important questions remain unanswered. This is not a criticism. It is simply the reality of scientific progress.

The widespread use of these therapies is relatively recent. The body, however, operates on timescales measured not only in weeks and months, but sometimes decades. [6, 32, 33]

As a result, several important questions remain open. What happens after discontinuation? Can improvements in signaling persist after treatment ends? To what extent do outcomes depend on the habits developed during the Terrain Window? How much of the benefit comes from weight loss itself? How much comes from improved signaling? How much comes from the interaction between the two?

These questions remain active areas of investigation.

One possibility is that the long-term outcome depends heavily on what occurs while the window is open. If body composition improves, if muscle mass increases, if food quality improves, if sleep improves, if metabolic flexibility improves. [23, 24, 25, 32, 33, 39]

Then the individual who exits the window may not be the same person who entered it. Millions of repair and remodeling events may have occurred under different conditions. New habits may have formed. New structures may have formed. New feedback loops may have emerged.

On the other hand, if nothing changes except temporary appetite suppression, some of the original pressures may eventually return. The city may gradually become noisy again.

This is one reason the Terrain Window may be more important than the drug itself. The window creates opportunity. What happens next depends on how that opportunity is used.

Another important question involves adaptation. Biological systems are remarkably adaptive. They constantly adjust to changing conditions. The same adaptability that allows healing can also complicate long-term interventions.

Scientists are still learning how these signaling systems respond over many years. This uncertainty should not be viewed as a weakness. It should be viewed as an invitation to remain curious.

The current evidence is encouraging. The early results are impressive. But biology has a habit of revealing new layers whenever we think we have reached the bottom.

That may be the most important lesson of all.

The deeper we look, the more interconnected everything becomes.

20. Key Insights

• The most interesting thing about GLP-1 drugs may not be that they reduce appetite.
• The most interesting thing may be what they reveal about how the body regulates appetite in the first place.
• Obesity appears to involve more than calories alone.
• Appetite, reward, metabolism and behavior are deeply interconnected.
• The body is not merely managing energy.
• The body is managing information.
• Fat tissue is not passive storage.
• Fat tissue is an active endocrine organ that continuously communicates with the rest of the body.
• Healthy fat whispers.
• Angry fat shouts.
• Leptin and insulin are communication systems.
• Modern obesity may involve signal distortion as well as excess energy storage.
• Modern humans live inside a constant signal storm.
• Food, stress, light, reward and information compete continuously for attention.
• GLP-1 drugs may temporarily restore signal clarity.
• The Terrain Window is this article's name for the opportunity created by that clarity.
• Weight loss is only part of the story.
• Remodeling is the deeper story.
• Fat loss reduces burden.
• Muscle building increases capacity.
• Biological systems appear to benefit from periods of reduced noise.
• Fasting, sleep and other restorative practices may help create those conditions.
• Structure affects signals.
• Signals affect structure.
• The body is built from feedback loops.
• Mitochondria sit at the center of energy production, repair and adaptation.
• Throughput matters.
• Maintenance matters.
• Infrastructure matters.

21. Final Reflection

For decades obesity was often presented as a simple equation: eat less, move more, try harder.

The success of GLP-1 drugs does not prove that this equation was wrong. But it strongly suggests that it was incomplete.

The body is not merely a calculator. It is a living regulatory system.

That is what makes the GLP-1 era so revealing. These drugs do not simply reduce intake. They expose how deeply appetite, reward, metabolism and behavior are already woven together.

They also remind us that meaningful change may involve more than lowering body weight. It may involve rebuilding the terrain in which signals are produced, received and acted upon.

Perhaps the most important lesson is that the body appears far more interconnected than we once believed.

The deeper we look, the more the boundaries between metabolism, reward, psychology, inflammation, structure and signaling begin to dissolve.

That conversation is still unfolding. Scientists will continue debating mechanisms. New discoveries will emerge. Current assumptions will be revised. Such is the nature of science.

But one insight already seems clear: the most important thing about GLP-1 drugs may not be that they help people lose weight. The most important thing may be that they reveal how the body regulates weight in the first place.

The drug is not the story.

The drug reveals the story.

Selected References

Obesity Trends and GLP-1 Outcome Trials

1. NCD Risk Factor Collaboration. (2017). Worldwide trends in body-mass index, underweight, overweight, and obesity from 1975 to 2016. The Lancet, 390(10113), 2627-2642. DOI: 10.1016/S0140-6736(17)32129-3. PMID: 29029897.
2. Ward, Z. J., Bleich, S. N., Cradock, A. L., et al. (2019). Projected U.S. state-level prevalence of adult obesity and severe obesity. New England Journal of Medicine, 381(25), 2440-2450. DOI: 10.1056/NEJMsa1909301. PMID: 31851800.
3. Wilding, J. P. H., Batterham, R. L., Calanna, S., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, 384(11), 989-1002. DOI: 10.1056/NEJMoa2032183. PMID: 33567185.
4. Jastreboff, A. M., Aronne, L. J., Ahmad, N. N., et al. (2022). Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine, 387(3), 205-216. DOI: 10.1056/NEJMoa2206038. PMID: 35658024.
5. Jastreboff, A. M., Kaplan, L. M., Frias, J. P., et al. (2023). Triple-hormone-receptor agonist retatrutide for obesity: A phase 2 trial. New England Journal of Medicine, 389(6), 514-526. DOI: 10.1056/NEJMoa2301972. PMID: 37366315.
6. Lincoff, A. M., Brown-Frandsen, K., Colhoun, H. M., et al. (2023). Semaglutide and cardiovascular outcomes in obesity without diabetes. New England Journal of Medicine, 389(24), 2221-2232. DOI: 10.1056/NEJMoa2307563. PMID: 37952131.

Incretins, Appetite, Glucagon and Reward

7. Holst, J. J. (2007). The physiology of glucagon-like peptide 1. Physiological Reviews, 87(4), 1409-1439. DOI: 10.1152/physrev.00034.2006. PMID: 17928588.
8. Baggio, L. L., & Drucker, D. J. (2007). Biology of incretins: GLP-1 and GIP. Gastroenterology, 132(6), 2131-2157. DOI: 10.1053/j.gastro.2007.03.054. PMID: 17498508.
9. Campbell, J. E., & Drucker, D. J. (2013). Pharmacology, physiology, and mechanisms of incretin hormone action. Cell Metabolism, 17(6), 819-837. DOI: 10.1016/j.cmet.2013.04.008. PMID: 23684623.
10. Kanoski, S. E., Hayes, M. R., & Skibicka, K. P. (2016). GLP-1 and weight loss: Unraveling the diverse neural circuitry. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 310(10), R885-R895. DOI: 10.1152/ajpregu.00520.2015. PMID: 27030669.
11. Blundell, J., Finlayson, G., Axelsen, M., et al. (2017). Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity. Diabetes, Obesity and Metabolism, 19(9), 1242-1251. DOI: 10.1111/dom.12932. PMID: 28266779.
12. Hendershot, C. S., Bremmer, M. P., Paladino, M. B., et al. (2025). Once-weekly semaglutide in adults with alcohol use disorder: A randomized clinical trial. JAMA Psychiatry, 82(4), 395-405. DOI: 10.1001/jamapsychiatry.2024.4789. PMID: 39937469.
13. Kenny, P. J. (2011). Reward mechanisms in obesity: New insights and future directions. Neuron, 69(4), 664-679. DOI: 10.1016/j.neuron.2011.02.016. PMID: 21338878.
14. Morton, G. J., Cummings, D. E., Baskin, D. G., Barsh, G. S., & Schwartz, M. W. (2006). Central nervous system control of food intake and body weight. Nature, 443(7109), 289-295. DOI: 10.1038/nature05026. PMID: 16988703.
15. Hall, K. D., Heymsfield, S. B., Kemnitz, J. W., et al. (2012). Energy balance and its components: Implications for body weight regulation. The American Journal of Clinical Nutrition, 95(4), 989-994. DOI: 10.3945/ajcn.112.036350. PMID: 22434603.

Leptin, Insulin and Adipose Communication

16. Friedman, J. M., & Halaas, J. L. (1998). Leptin and the regulation of body weight in mammals. Nature, 395(6704), 763-770. DOI: 10.1038/27376. PMID: 9796811.
17. Myers, M. G., Cowley, M. A., & Munzberg, H. (2008). Mechanisms of leptin action and leptin resistance. Annual Review of Physiology, 70, 537-556. DOI: 10.1146/annurev.physiol.70.113006.100707. PMID: 17937601.
18. Petersen, M. C., & Shulman, G. I. (2018). Mechanisms of insulin action and insulin resistance. Physiological Reviews, 98(4), 2133-2223. DOI: 10.1152/physrev.00063.2017. PMID: 30067154.
19. Kershaw, E. E., & Flier, J. S. (2004). Adipose tissue as an endocrine organ. The Journal of Clinical Endocrinology & Metabolism, 89(6), 2548-2556. DOI: 10.1210/jc.2004-0395. PMID: 15181022.
20. Ouchi, N., Parker, J. L., Lugus, J. J., & Walsh, K. (2011). Adipokines in inflammation and metabolic disease. Nature Reviews Immunology, 11(2), 85-97. DOI: 10.1038/nri2921. PMID: 21252989.
21. Hotamisligil, G. S. (2006). Inflammation and metabolic disorders. Nature, 444(7121), 860-867. DOI: 10.1038/nature05485. PMID: 17167474.
22. Weisberg, S. P., McCann, D., Desai, M., et al. (2003). Obesity is associated with macrophage accumulation in adipose tissue. Journal of Clinical Investigation, 112(12), 1796-1808. DOI: 10.1172/JCI19246. PMID: 14679176.

Metabolic Flexibility, Muscle, Fasting and Autophagy

23. Galgani, J. E., Moro, C., & Ravussin, E. (2008). Metabolic flexibility and insulin resistance. American Journal of Physiology-Endocrinology and Metabolism, 295(5), E1009-E1017. DOI: 10.1152/ajpendo.90558.2008. PMID: 18765680.
24. Wolfe, R. R. (2006). The underappreciated role of muscle in health and disease. The American Journal of Clinical Nutrition, 84(3), 475-482. DOI: 10.1093/ajcn/84.3.475. PMID: 16960159.
25. Strasser, B., & Pesta, D. (2013). Resistance training for diabetes prevention and therapy. Sports Medicine, 43(5), 397-408. DOI: 10.1007/s40279-013-0023-8. PMID: 23529385.
26. de Cabo, R., & Mattson, M. P. (2019). Effects of intermittent fasting on health, aging, and disease. New England Journal of Medicine, 381(26), 2541-2551. DOI: 10.1056/NEJMra1905136. PMID: 31881139.
27. Longo, V. D., & Mattson, M. P. (2014). Fasting: Molecular mechanisms and clinical applications. Cell Metabolism, 19(2), 181-192. DOI: 10.1016/j.cmet.2013.12.008. PMID: 24440038.
28. Mizushima, N., & Komatsu, M. (2011). Autophagy: Renovation of cells and tissues. Cell, 147(4), 728-741. DOI: 10.1016/j.cell.2011.10.026. PMID: 22078875.

Mitochondria, Membranes, Body Composition and Remodeling

29. Nunnari, J., & Suomalainen, A. (2012). Mitochondria: In sickness and in health. Cell, 148(6), 1145-1159. DOI: 10.1016/j.cell.2012.02.035. PMID: 22424226.
30. van Meer, G., Voelker, D. R., & Feigenson, G. W. (2008). Membrane lipids: Where they are and how they behave. Nature Reviews Molecular Cell Biology, 9(2), 112-124. DOI: 10.1038/nrm2330. PMID: 18216768.
31. Lingwood, D., & Simons, K. (2010). Lipid rafts as a membrane-organizing principle. Science, 327(5961), 46-50. DOI: 10.1126/science.1174621. PMID: 20044567.
32. Garvey, W. T., Batterham, R. L., Bhatta, M., et al. (2022). Two-year effects of semaglutide in adults with overweight or obesity: The STEP 5 trial. Nature Medicine, 28(10), 2083-2091. DOI: 10.1038/s41591-022-02026-4. PMID: 36216945.
33. Koliaki, C., Liatis, S., Kokkinos, A., et al. (2024). Effect of glucagon-like peptide-1 receptor agonists and co-agonists on body composition: Systematic review and network meta-analysis. Metabolism, 157, 156113. DOI: 10.1016/j.metabol.2024.156113. PMID: 39719170.

Systems Biology, Inflammation, Sleep and Lifestyle Context

34. Kitano, H. (2002). Systems biology: A brief overview. Science, 295(5560), 1662-1664. DOI: 10.1126/science.1069492. PMID: 11872829.
35. Alon, U. (2007). Network motifs: Theory and experimental approaches. Nature Reviews Genetics, 8(6), 450-461. DOI: 10.1038/nrg2102. PMID: 17510665.
36. Spiegel, K., Leproult, R., & Van Cauter, E. (1999). Impact of sleep debt on metabolic and endocrine function. The Lancet, 354(9188), 1435-1439. DOI: 10.1016/S0140-6736(99)01376-8. PMID: 10543671.
37. Forsythe, L. K., Wallace, J. M. W., & Livingstone, M. B. E. (2008). Obesity and inflammation: The effects of weight loss. Nutrition Research Reviews, 21(2), 117-133. DOI: 10.1017/S0954422408138732. PMID: 19087366.
38. Edgerton, D. S., & Cherrington, A. D. (2011). Glucagon as a critical factor in the pathology of diabetes. Diabetes, 60(2), 377-380. DOI: 10.2337/db10-0426. PMID: 21270249.
39. Diabetes Prevention Program Research Group. (2002). Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine, 346(6), 393-403. DOI: 10.1056/NEJMoa012512. PMID: 11832527.
40. Speakman, J. R., Levitsky, D. A., Allison, D. B., et al. (2011). Set points, settling points and some alternative models: Theoretical options to understand how genes and environments combine to regulate body adiposity. Disease Models & Mechanisms, 4(6), 733-745. DOI: 10.1242/dmm.008698. PMID: 22065844.
41. Sender, R., & Milo, R. (2021). The distribution of cellular turnover in the human body. Nature Medicine, 27(1), 45-48. DOI: 10.1038/s41591-020-01182-9. PMID: 33432173.
42. Volkow, N. D., Wang, G. J., Tomasi, D., & Baler, R. D. (2013). Obesity and addiction: Neurobiological overlaps. Obesity Reviews, 14(1), 2-18. DOI: 10.1111/j.1467-789X.2012.01031.x. PMID: 23016694.
43. Broussard, J. L., Ehrmann, D. A., Van Cauter, E., Tasali, E., & Brady, M. J. (2012). Impaired insulin signaling in human adipocytes after experimental sleep restriction. Annals of Internal Medicine, 157(8), 549-557. DOI: 10.7326/0003-4819-157-8-201210160-00005. PMID: 23070488.

ATP Production and Mitochondrial Dysfunction

44. Boyer, P. D. (1997). The ATP synthase: A splendid molecular machine. Annual Review of Biochemistry, 66, 717-749. DOI: 10.1146/annurev.biochem.66.1.717. PMID: 9242922.
45. Lowell, B. B., & Shulman, G. I. (2005). Mitochondrial dysfunction and type 2 diabetes. Science, 307(5708), 384-387. DOI: 10.1126/science.1104343. PMID: 15662004.