According to the CDC, over one-third of Americans are considered clinically obese, and two-thirds are considered overweight or obese. It is a growing epidemic in our country that has yet to show signs of slowing down. In fact, the rates of obesity are increasing with three states home to obesity rates above 35%, 22 states above 30% and 45 states above 25% obese.

There is a number of influencing factors, but the fact remains that the U.S. has a staggering weight problem. Unfortunately, there is a lot of misinformation about diet and weight loss, and it causes more harm than good. Thankfully, through psychology, we can learn why our bodies do what they do and how to control them to better our health.

Via unapologeticallyamerican

Understanding the psychology of eating starts with the brain. We must consider the internal structures and evolutionary history of the brain to think of it in relation to diet and exercise. To begin, think about the origin of the human brain. Modern humans, as far as we know, existed on Earth for around 200,000 years. But the structures of the brain are far older than that. Our brains developed under the pressure of natural selection. Brains that were capable of keeping us alive were more likely to reproduce, meaning that modern humans have brains that were built to survive.

Evolution happens on a massively large scale as in millions of years. Far before humans existed, the basis of the human brain developed in lifeforms. Because of this massive time scale, our brains and bodies are “evolutionarily older” than we are. Think of your brain as a machine that is millions of years old and was built to handle problems millions of years ago. You may only be 20 or 30 years old, but the structures in your brain have been around for millions of years. Herein lies the problem with diet in modern society. Our brains were built to keep us alive while living in forests and caves and hunting food with sharpened sticks, not to navigate a modern lifestyle.

Technology expanded at an exponential rate and it surpassed our brains quickly in terms of evolution. In addition to technology, the food industry surpassed our brains as well. Your brain was built to keep you from starving: it coordinates your body and what you eat with the assumption that you could starve. It plans for long periods without any food, and it evolved to help mitigate the damage those periods cause. It mitigates starvation by storing lipids, or fat, on your body.

Imagine you are a human living 15,000 years ago before modern agriculture existed and you had to hunt for our food to survive. If you manage to get more food than the bare minimum, your body will want to hold on to that. Your brain and body recognize how much food you need to survive, and anything extra is packed on as fat to use for later in case you cannot find food for a while.

Via wikimedia

With this in mind when we turn to the 21^st century, we see the problem emerge. Food is no longer scarce for most of the U.S. There are two separate grocery stores less than a mile from where I live. We have access to an endless supply of food in the U.S., and starvation is not a threat. However, our brains were built to act with starvation in mind. So, even though most Americans will never have to worry about starving, your brain and body do not know the difference.

The processes put in place to store food for later were built far before we had access to this much food, meaning those processes are still at work today. Our food has become increasing calorie dense, meaning it has more energy available in it. If your body cannot use all of the energy available in the food you ate, it will pack the rest away as fat. You may have heard the saying “calories in, calories out” regarding weight loss. This saying is referring to the fact that if you eat more calories than your body can use, you will pack the rest on as fat. If you eat less than your body can use, you will lose fat.

This is the crux of weight control. If you eat more energy (calories) than your body needs, it will pack on the rest as fat because your body and brain are programmed to prevent starvation in the future. Your body says “we have this extra energy now, let’s save that in case we don’t have extra food later.” But because we never run out of food, that excess energy is never used and it stays fat. Years and years of your body’s survival mechanics not working in the modern world causes a buildup of fat, and thus obesity.

The problem is not so simple, though. Your brain is far more dangerous than your body when it comes to eating. Dopamine is probably one of the most well-known neurotransmitters in pop psychology. The extent of the common understanding of dopamine is that it makes us feel good. The reality is much more nuanced, however.

Dopamine is called the “reward” neurotransmitter because of its role in forming patterns and habits. For example, brain structures called the Medial Forebrain Bundle is responsible for rewarding you for following through with plans. It does this by giving you a surge of dopamine. Pop music manipulates dopamine by creating predictable patterns in music, which your brain rewards you for predicting.

Basically, anything that you feel accomplished in is the result of Dopamine somewhere in your brain. Dopamine is also the chemical responsible for major addictions to drugs, such as cocaine. We constantly seek a dopamine rush from every activity we do: we are addicted to dopamine.

As it happens, sugar is implicated in huge increases in levels of dopamine in a part of the brain called the Nucleus Accumbens. A study of lab rats who were addicted to cocaine vastly preferred taking sugar water to cocaine when given the choice. The levels of dopamine in the rats was comparable and sometimes even higher when taking sugar over cocaine. While not entirely representative of humans’ interactions with sugar, it clearly shows that due to an increase in dopamine, sugar is an addictive substance.

Via mic.com

So why does our brain reward us for eating something that contributes to weight gain? It goes back to the point of your brain and body wanting to survive. Sugar is incredibly rich in calories: it is an “energy dense” food. Though sugar is processed by your liver, due to its density, the body cannot use all of the available sugar immediately.

Your pancreas produces insulin to turn that sugar into fat to store for later. Normally, this would be done so that you have the fat to use as energy in periods with little food. But since we have no shortage of food, and that food has no shortage of sugar, our survival mechanism fails us and we become obese. Fat is packed on to prevent starvation in the future, when starvation never comes the fat never leaves, and more fat is packed on top.

Our bodies and brains know how to keep us alive. However, the processes that were designed to do so are older than our modern diet so the result is obesity. Increases in our sugar intake means higher calories, which your body packs on as fat. Because we never go without food, the fat is not used as intended.

When more sugary, high-calorie foods are consumed, they are packed on top of the fat that was for “survival.” The danger in today’s society is not obesity, as that is already an ingrained problem. The danger now is that obesity is becoming the norm, and those who were once deemed unhealthy are now being viewed as healthy and normal.

This will ultimately cause more obesity by normalizing this unhealthy weight gain. Next week, I will discuss how eating habits can be changed to lose weight properly, using what we know about the brain and body to our advantage.