This is a very important question that has been getting a lot of attention lately. The obesity problem continues to grow across the world. In the United States, the problem has reached disastrous proportions. Obesity now affects one in three Americans. Two-thirds of Americans are overweight. Children are struggling with excess weight like never before. The logical question: why?

Here’s why. Or at least why we think…

Genetics.
Gluttony.
Sloth.
Gluttony and sloth.
Fat.
Carbohydrates.
Refined foods.
Alcohol.
Infection.
Gut disbiosis.
Food reward.
Inflammation.
Toxins.
Food toxins.
Micronutrient deficiency.
Hormones.
Sleep dysregulation.

The list could (and does) go on…

Truth is, it’s probably all of these to a certain degree. What proportion? That depends on the person.

Therefore, the answer to all of the following questions is, “it depends” or “probably”…

Do our genes make us fat?
Does overeating make us fat?
Does inactivity make us fat?
Does overeating paired with inactivity make us fat?
Does fat make us fat?
Do carbohydrates make us fat?
Do refined foods make us fat?
Does drinking alcohol make us fat?
Do infections make us fat?
Does our bacteria make us fat?
Do rewarding foods make us fat?
Does inflammation make us fat?
Do toxins make us fat?
Do food toxins make us fat?
Does micronutrient deficiency make us fat?
Do hormonal problems make us fat?
Does sleep deprivation make us fat?

Every single one of these questions is important and is worth asking. They all play a role in why we are fat to a certain degree, some more than others, depending on the individual.

The bottom line is we live in a world that is incongruent with our biology. Everything we do is at odds with our genes. Our natural systems struggle with what we expose our body to. We shouldn’t be surprised that we are getting fatter by the year. We are living in a world that has been created to make us fat and sick. Those that are healthy are the abnormal ones. Whether it is due to good genes, luck, healthy living or some other variable we don’t know about yet, the healthy people are becoming fewer and farther between. They are now the freaks. What a shame that we have gotten to the point where trying to live naturally and healthfully is looked upon as a weird or abnormal thing. We all have it within our capability to be healthy. How? By living in a way that is consistent with our biology. By managing all of the contributors to obesity and disease. Living a more “natural” life will mitigate the impact of nearly all the potential impacts of modern life. Let’s take a look at each these modern impacts and the associated theories of obesity and disease.

Genetics
Human bodies are designed to be lean and healthy. They are also designed to adapt to the environmental pressures put upon the system. If given a good environment they will express the healthiest characteristics possible for that person. If given a poor environment, they will express the weaker side. We are all given genetic stock that is from a lean, healthy, viable and survival-based platform. A few people are given versions of these genes that have been weakened by lineage, disease or a poor fetal/developmental environment. These people are still capable of leanness and health if their behavior doesn’t promote the expression of their genetic weakness. They may have less room for error but genetically disadvantaged people are still capable of health. “Poor genetics” can put a person at a disadvantage but are almost never an excuse for obesity and disease.

Overeating
There is little argument that humans are eating far more than ever before and much more than we need. Eating more food than we can biologically use, particularly in the form of refined food products, will lead to weight gain. The problem is it’s not the underlying reason. Overeating is a symptom of body malfunction. We eat too much when something in our body’s metabolism isn’t working well. So, yes (technically) overeating can cause people to be fat but the real question lies in why they overeat, which we will explore more down the list.

Inactivity
There is also little argument that humans are also less active than ever before. This too plays a role in the obesity epidemic. Activity allows the body to keep energy utilization at the most efficient rate possible. We live in a world that is filled with convenience, remote controls, technology, cars, escalators, food delivery, etc. But this is not the cause of obesity. Humans do not become overweight simply because they aren’t active. Typically people are less active because their body is not working well. Another case of mistaken identity. Inactivity is usually a symptom of obesity. When the body starts to travel down the path of metabolic dysfunction it desires to expend less energy. This means we are much more likely to limit our activity and the vicious cycle begins. So, yes (technically), inactivity contributes to obesity but it is not the sole cause.

Overeating and Inactivity
Nearly every critique of the current health crisis includes the phrase, “we eat too much and exercise less” and many conclude it is just that simple. As noted above, although this lethal combination does contribute to the problem, the reason we eat too much and don’t exercise enough is likely more a symptom of obesity and not the cause in and of itself.

Fat Consumption
For a few decades now, the mantra, particularly from conventional wisdom, has been that eating fat makes us fat. Everyone knows it’s true. That’s why we have been told that if we want to lose weight and be healthy we should limit our fat intake. This is unfortunately a bit short sighted at best. Once again, eating fat can make you fat if you eat a bunch of it, although fat consumption limits itself pretty well in a natural environment. Just eating fat does not make people fat. Overeating fat is usually only a problem when eaten along with a bunch of refined carbohydrates and other man made food or if you’re eating man-made fats (industrial seed/vegetable oils soybean, corn, canola, etc. and trans/hydrogenated fats). There is a misconception that fat goes into your belly and ends up on your hips, thighs or belly. It can, yes, but it’s not because you’re eating fat, it is because your body is not working well. In fact, eating a high percentage fat diet is actually a very effective tool at losing weight very quickly.

Carbohydrate Consumption
One of the most common villains cited in the obesity crisis is the macronutrient affectionately known as “carbs”. Taking a step back to before the late 70’s, many have shifted focus away from fat and onto carbohydrates. The belief that carbs make us fat has deeper roots historically and biologically than the fat hypothesis. Consuming carbohydrates in excess can make you fat. However, once again, there is more to the equation than meets the eye. This is likely a better approach than limiting fat consumption as people are more likely to consume empty calories through carbohydrates. Here lies the gray area. Carbohydrates in and of themselves are not the enemy and certainly not the sole cause of obesity. Carbs are difficult for many peoples’ metabolisms, this is certain. Carbs are not a problem for everyone, as many people do in fact manage their weight or lose weight on a high carb diet.

Refined Foods
Perhaps the most popular stance in the health world is that refined foods are the major problem in today’s society. Before the food industry revolution of the last few decades, refined foods were a part of our diet but not a staple. Now you can talk to people that haven’t had anything other than a refined food in weeks, months or even years. Usually, the consumption of refined foods is directly related to a person’s weight. High calorie, quick digesting, incredibly stimulating and easy to obtain foods can put weight on a human body like nothing else on the list of suspects. But are refined foods, in and of themselves, the problem? They are a problem, but you can’t blame them completely. A healthy person can eat refined foods and not become fat. An unhealthy person probably can’t. Do refined foods make us unhealthy or do unhealthy people eat refined foods? Once again, part of the problem but not the whole problem.

Alcohol
Booze. Many a college freshman can relate to the supposed weight impact of alcohol. Although beer bellies may appear to incriminate alcohol, there is little evidence that alcohol is the problem. It can cause weight gain through a few mechanisms but only rarely is it the only issue. It doesn’t help that many people eat some pretty gnarly foods when they drink alcohol. Alcohol makes it harder for the body to regulate those calories but it is not the reason we are fat. Too many people suffer from obesity that never drink alcohol and people throughout the world drink all types of alcohol and have no obesity. Booze can occasionally be a problem or often compound the problem but that’s about it.

Infections
This is an interesting one and has been gaining some attention lately. I’m grouping bacterial, viral, fungal and all other pathogens together into the same category because they all present the same problem: an intruding pathogen can disrupt the body’s ability to manage itself. A symptom of an invading “germ” can be weight gain. Some people feel much of our weight and health problems come back to infections. Without addressing the underlying pathogens disrupting our metabolisms, we will never be able to manage obesity. There is likely some truth to this as many people are dealing with several low level infections that are likely causing them to cave sugar, be lethargic or have sleep problems, all of which can add up to extra weight. Although it is hard to believe it is the main reason obesity is rampant it is something that people need to be aware of because infections can lie at the heart of their weight gain.

Gut Disbiosis
Another theory with growing support. The human body contains about 1 trillion cells. It contains 10 trillion bacteria. We are more bacteria than human by a long shot. Under the right circumstances and in the right balance, bacteria control nearly everything in the body from digestion to immunity and back to energy regulation. If out of balance (termed disbiosis) bacteria can create havoc in the body and, through a couple of different mechanisms, often result in altered bodyweight control. As an example, an over abundance of unfriendly bacteria in the gut can lead to unnatural and often uncontrollable sugar cravings. Most bacteria feed and thrive off sugar, particularly species that are undesirable, and that need for fuel often ends up in the host species (humans in this case) increasingly seeking out quick digesting sources of glucose. Uncontrollable sweet cravings equal weight gain for everyone I’ve ever met. Other regulatory systems are affected by disbiosis and can all contribute to weight gain. There is little doubt that this is a bad thing. There is also little argument that in developed societies humans very rarely have healthy gut biomes. But is this the main mechanism in obesity? We still aren’t too sure. It plays a role (and could even be causative in many people) but it doesn’t appear to be the only culprit.

Food Reward
Another line of thinking that has been getting some backing lately is the food reward and palatability theory of obesity. Simply stated, obesity exists as a result of overly palatable food and the subsequent stimulation of brain reward centers. In essence, super stimulating food has become an addictive substance. Proponents of this argue that the hyper palatable food disrupts appetite and metabolic regulation and creates an environment that makes it easy to gain weight. Without access to and injestion to overly rewarding food, the body’s natural appetite and weight regulation will work properly and a natural weight will be maintained. Humans fill up fast on plain potatoes and meat but can eat much more if you add butter and salt to the potato and marinade to the meat, even more than the simple addition of those calories would equal. By increasing the flavor we have made it a more rewarding food. Now take it to the extreme form of french fries and hamburgers and you can see how easily food palatability and reward can retrain the human brain and body to consume much more food than necessary to survive. This is a good theory, but are there cases of obesity where food palability and reward is low? Yes. Most of the world now has access to westernized food which makes it difficult to compare but we have seen evidence of obesity under low palatable food environments.

Inflammation
Underlying every health problem we know about is inflammation. Although necessary under acute instances for healing, chronic inflammation is a metabolic nightmare. In general, a body in a state of inflammation is a highly stressed body. Under times of stress, the body strives to gather and maintain resources, one of which is fuel. Storing fuel, by means of altered metabolism (increased fuel storage and decreased fuel liberation), protects us from the long term detriments of stress. An inflamed body is holding onto weight to protect itself. Therefore, the more inflamed the body is, the more it is likely to gain weight. So the real question is: what causes inflammation? Here’s where it gets tricky again. Virtually any stressor can lead to or cause inflammation, including many of the causes of obesity we are covering. Pathogens, toxins (food and environmental), bacteria, mental/emotional/physical stress, overeating, overexercising, alcohol, allergens, sleep deprivation, and on and on. Nearly everything around us is a potential stress and inflammation. So we come back to what is the main culprit and how we manage inflammation. More gray area.

Toxins
This refers to environmental toxins, which include anything we encounter on a daily basis, ranging from radiation, to plastic, electromagnetic waves and air pollutants. The basic premise is that exposure to these toxins on a chronic basis disrupts our body’s homeostasis on a number of levels and subsequently impacts the ability to maintain a healthy weight. Though there may be some promise in this area, it still appears to be much more to obesity than exposure to plastics or air pollution.

Food Toxins
Another theory with roots in the underlying stress category. Whether it be chemicals/pesticides, bacteria/viral/fungi, hormones, preservatives/dyes or food allergens the food toxin argument is popular and growing quickly. All of these toxins can severely damage the body, creating inflammation and affecting weight control. Although historically we have been concerned with toxins such as pesticides and artificial sweeteners/preservatives some of the more recent attention has been on allergens and food sensitivities. Gluten, (gliadin, more specifically) the latest villain and example of a vilified food toxin, has been labeled public enemy number one and is blamed as the cause of a number of health ailments. There appears to be a growing body of evidence that humans are not well adapted to gluten/gliadin, particularly in its current hybrid form. Is it, and other food toxins, like it, the cause of obesity? They certainly contribute to the barrage of stresses our body endures on a daily basis but are likely not the main contributor.

Micronutrient Deficiency
A theory with growing support looks at vitamin and mineral deficiencies as the leading driver of obesity. Simply put, people are low in some (or many) of the crucial micronutrients (vitamin C, magnesium, calcium, B vitamins, etc.) for a couple reasons. The two main ones being that we eat too much junk food that doesn’t contain nutrients and even our real foods are lacking in the nutrients they had even a few decades ago due to poor soil quality and animal living conditions. Since we are also living in a world that demands more vitamins and minerals to function, there is a big gap. The body, trying to obtain all of the necessary nutrients, drives hunger up. So we eat more food in search of vitamins and minerals. More energy goes into the body and (without adequate nutrients to process it well and manage metabolism) it gets driven into fat storage. The process continues and since we never get adequate nutrients we remain hungry, keep eating and gain weight. Although there is a good argument here, the complexity of the body makes this theory likely only an assisting pathway and not the cause in and of its self.

Hormones
The most general category with the most players involved. Hormones rule just about everything in the body so many feel that weight gain is no different. Hormones tell the body what to do with energy, metabolism and fat storage. It is pretty well accepted that thyroid hormone deficiency cn lead to weight gain from a sluggish metabolism. Sex hormones (testosterone, estrogen) are widely known to contribute to energy management. Cortisol, a stress hormone, negatively impacts weight if chronically elevated or disrupted. Leptin tells our brain how much fat we have, if this system gets off track, we can gain weight. Insulin, one of the most maligned hormones out there, drives energy delivery and is thought to be the main player in fat storage. Several other hormones control hunger, satiety and energy management and are thought to cause weight gain when malfunctioning. Here’s the thing: even if these hormones do cause us to gain weight, they are not the ultimate cause. The root cause is whatever caused the hormones to go haywire in the first place. So, yes, hormones make us fat but other things lead to the hormonal problems. Blame the other things, not the hormones that are simply a reactive adaptation by the body.

Sleep Disregulation
Very simple: bad sleep (a big stress) causes a string of events (including hormonal shifts) that lead to overeating (particularly carbohydrates and sugar) and reduced metabolism which results in weight gain. This theory is limited in scope and is likely not the cause for everyone but it is one of the most direct theories at the root cause level. Much of the other theories on obesity can be impacted or explained by not sleeping enough or getting adequate good quality rest.

A few bonus theories…
Fast Food
Also very simple: fast, processed food is high in calories and toxins, low in nutrients and very convenient. The availability of fast food is overwhelming now and, due to it displacing home made higher quality food, as a result people are eating more and gaining weight. Once again, probably true to a certain degree that fast food contributes to obesity but it certainly is not the cause by itself. You can eat fast food and not gain weight, which has been done anecdotally several times. It is much more likely that the bodies suffering from other problems are more likely to gain weight and are also more likely to eat fast food. It would appear that although a contributor, fast food consumption is more correlated to weight gain than the main cause.

Eating Out/On The Run/Away From Home
This is another one that holds a bit of truth but is another example of a contributing factor. Eating away from home and/or on the run is blamed for two reasons: food quality and food environment. Proponents of this obesity theory point to food quality as a major problem. Most of the time, eating away from home means bad food. Fast food, junk food, snacks, sodas and often questionable restaurant food. This, if done enough leads to obesity. The other leg of thought is that food environment plays a role. Eating at home is not only usually better quality, it is slower, more thoughtful and present and stimulates better digestive processes. Eating out or on the run often equates to rush, hurry and stress which negatively impacts digestion and use of energy. Simply put, eating at home helps us slow down and eat better suited to our physiology. Although this is a fantastic thought and certainly plays a role in people’s weight regulation challenges it is, like most of these theories, only a helping hand.

Seasonal Discordance
One of the most intriguing and potentially promising theories on obesity is seasonal discordance. The basics: we don’t live in harmony with the seasons that regulated our weight naturally most of our existence. As the days grow longer and temperature warms the body, exposed to more food and carbohydrates, engages in processes that maximize growth, energy use and storage. When the days shorten and climate cools, combined with less food carbphydrates, the body processes shift toward conservation, repair and recovery. Energy stored (e.g. fat) during the prosperous warmer months is used during the colder months for insulation and fuel for survival. The tide comes in, the tide goes out, season after season and year after year. The body balances quite masterfully between energy surplus and deficit. The problem arises when we don’t have balance, such as the endless summer phenomenon. This is when it stays light all the time (via artificial lights and computers), never gets cold (heaters/air conditioning) and the feast never ends (constant availability of food and carbohydrates). Perpetual summer (energy storage) with no winter (energy usage) gets us in trouble. This imbalance is devaststing on our physiology. With no break from being bombarded with energy, the body just continues to put on weight. Without winter cues it is very difficult to stimulate the body’s weight loss. Even calorie deprivation (diets) is not enough when it’s paired with long days and warm/temperate climate, which are stronger physiological season cues to the body. Similarly, eating out of season (bananas in winter, low carb in the summer) is also very confusing to the body and can hamper our ability to manage energy well. In general, the seasonal discordance theory is one of the most central in terms of root cause although it only explains some of why obesity ends up as a problem.

Ok, although there are are others, those are the most common/popular theories on why we are fat. As you can see, there is no one reason that explains obesity but many offer some good rationale behind human weight problems.

So Why Are We Fat?
After all that, do we have an answer to this question? In short, no. If we want to blame something, the best we could do is say a collection of factors, depending on the person cause weight gain. Every human body is so different that it’s impossible to put the “cause” label on any one or two things.
What we do know is that our environment promotes weight gain. All of these theories are right to a certain degree and offer some truth. People are fat because of every one of the reasons we covered above. The current lifestyle most of us live has a number of things that are encouraging weight gain and as a result many things lead to getting or staying fatter.

Here’s the thing: I think most obesity theories are looking at down stream impact or symptoms of a disconnected body. All of these are blaming things that are a result of a body malfunctioning. We gain weight because we eat more because hormones are off but why are they off in the first place? Did an infection cause this? If so, was it a weak body that got infected? Blame the infection or blame the weak body? Then what led to the weak body? Good functioning humans don’t have a problem maintaining their weight.

We are fat because we are malfunctioning. Why are we malfunctioning? That is the golden question. My guess is that it lies somewhere in the disconnection realm. Our biology is out of sync with our environment. Lack of sleep, sunlight, real food, seasonality and movement are all incongruent with optimal functioning. Humans that don’t live holistically and naturally usually start malfunctioning. Once the body starts malfunctioning, it becomes vulnerable to the impact of these obesity stimuli theories that wouldn’t be a problem to a well functioning person. Certainly some humans are more resilient and function better under the stress of modern life but what lies at the heart for most people is a disconnect to being a natural human.

The Bare 5 Bottom Line on Why We Are Fat:
1. There are dozens of reasons and theories on weight gain.
2. Some are better than others but no single one explains obesity for everyone.
3. Humans are incredibly different and are likely impacted by a combination different weight gain stimuli.
4. Looking at the downstream impact/result/symptoms of obesity instead of the upstream cause is part of the reason there are so many theories on obesity.
5. The best idea of “cause” is somewhere in this realm: disconnected humans start to malfunction and paired with a modern obesity promoting environment this leads to a body that can’t manage energy well, leading to weight gain.

Don’t worry about what makes you fat, worry about getting yourself functioning properly and all of the things that lead to obesity won’t have nearly the same impact.

Thanks for reading, have a great day.