Why we overeat

You see it at home, work, social gatherings and of course restaurants.? People consuming large amounts of highly processed foods with no regard of what it may be doing to their bodies and even the effect it’s having on their brain.

Below, you're going to learn what drives us towards these types of foods along with some ways to control our desire to eat them, especially in such large quantities.

Here are the top six sources of calories in the U.S. diet as of 2006:

-????????? Grain-based desserts (cakes, cookies, donuts, pies, and related?items)

-????????? Yeast?breads

-????????? Chicken and chicken-mixed?dishes

-????????? Soda, energy drinks, and sports?drinks

-????????? Pizza

-????????? Alcoholic beverages

Not only do these foods have negative effects on our health but they contain properties that the brain is hardwired to look for and are very easy to get as we are constantly exposed to them socially as well as through advertising.? Furthermore, along with food being the cheapest it’s ever been, there is very little in the way of a barrier to obtaining them (very little effort).? As we’ll see shortly, this is very important from an ancestral survival point of view.

So how do you get a human to voluntarily overeat?? It turns out, as we’re going to see in a study done by Eric Ravison’s group in 1995, it’s pretty easy:

"The goal of the study was to test a new food dispensing device that was designed to accurately measure food intake in humans.? It was basically a giant vending machine full of a variety of different types of foods, many of which were calorie dense and highly palatable.? Subjects were placed in a research setting where they had free access to these foods for seven days.? The researchers noted these people immediately began eating a much larger number of calories, exceeding their normal calorie requirements by over 50% and gained seven pounds over seven days."

One of the reasons this study was so “successful” was the convenience factor.? The more convenient the food, the more we will eat.

Wired to binge

You’re brain…on junk food.

You learned earlier that the brain is hardwired by natural selection to look for certain properties in food, but why?? These are the properties that would have sustained the survival and reproduction of our ancestors.? We have sensors in the mouth and small intestine that detect these substances that send a signal to the brain that causes dopamine, a neurotransmitter which plays a major role in the motivational component of reward-motivated behavior, to be released.

So what are these substances?? They are things like protein, carbs, fats, salt and glutamate (meaty, umami flavor).? These substances stimulate the brain circuits that drive us to overconsume.? These things were much less available in the time of our ancestors.

For example, the place we originally got glutamate from was cooked meat which we discovered how to do 100,000s of years ago.? This was very rewarding because it increased the amount of protein and calories that can be extracted and digested along with killing deadly parasites.? As technology proceeded with introduction of bowls and other tools we developed the ability to boil bones for bone broth, which is an even richer source of glutamate.? From there we progressed into making fish and soy sauce.? The process of concentrating glutamate culminated in 1908 when a Japanese researcher isolated pure monosodium glutamate.

Basically we figured out over time how to isolate the active ingredient in things that taste meaty which our brains crave.? We can now add it to any food in crystalized form.

The key point here is that the active ingredient is now divorced from any sort of nutrition that it was originally associated with and pointed us toward.

This is actually paralleled with the processing of drugs like cocaine and heroin.?

For example, the traditional people of South America used the leaf of a coca plant as a mild stimulant and appetite suppressant, similar to caffeine.? It’s a very mild drug used in a constructive way, but if you purify the active ingredient it turns it into what we call cocaine, a very addictive drug that causes a dopamine spike in your brain.? Then, if you further process the cocaine, which makes it easier to cross the blood, brain barrier, we now have crack cocaine which is an even more addictive drug.

Through technological development, we’ve not only broken down glutamate, but a couple of other substances that specifically trigger reward pathways in the brain.? You’ll learn about this reward system soon, but first let’s talk about these other substances which we’re all familiar with…fat and sugar.?

Fat intake hasn’t gone up much, but our added fat (namely from oils and butters) has quite a bit.? These are added to foods that ordinarily don’t contain much fat and dramatically increase the reward value to the brain.

Sugar is another one, like monosodium glutamate, that has been purified down to the absolute active ingredient in crystalized form.? Since 1822 our consumption of added sugar has gone up something like twenty fold.? This doesn’t include the natural sugar that’s found in fruits and vegetables.?

In addition to the convenience and persuasiveness in our personal environment, the actual properties of food have changed in a way that make them more appealing to the brain that drive consumption to a greater degree.

In the modern world we’re accustomed to having our palates entertained in such an extreme way that would have never been experience by our ancestors.

As you learned earlier, when we eat a food that’s very concentrated with these properties (pizza with a soda, ice cream, cake, donuts, potato chips) there is a large dopamine spike.? The more dopamine spikes, the more it triggers this process of learning and motivation.? Furthermore, your brain learns to prefer the foods that contain these substances.

For example, let' say you eat a slice of pizza, your brain gets wind of all of the starch, fat, protein, salt and says “This is an awesome source of the things I’m looking for, I want this again.”?There’s a dopamine spike and what this does is cause your brain to remember all of the sensory ques that were associated with that pizza; the smell and sight of it, the situation you were in, the people you were with, name of the restaurant.? All of these things get positive reinforcement, which means that all of these sensory ques get turned into motivational triggers the next time you encounter them.? Now your brain is more motivated by these ques so the next time you smell that pizza, see the greasy box, drive by the restaurant or hang out with the friend you always have pizza with, that’s a cue for your brain to say, “Oh, this is a situation in which I can get pizza.? I remember this and it’s a chance I can get a food I really like on some fundamentally hardwired level.”? This triggers that motivation to obtain and eat that pizza which is something that’s commonly called a craving.

The brain is highly motivated by sugar and its preference is deeply wired.? Children who are born without a cerebral cortex (the higher part of the brain that make us able to think) still respond to sugar with the stereotypical facial expressions that indicate pleasure.? In rats, you can deactivate most of the brain and they will still react to sugar.? The foods that most people crave or get “addicted” to contain a combination of high sugar and high fat.?

Not many people crave foods that only contain sugar with no fat or salt like fruit or hard candy.? There’s a much stronger motivational response and pleasure when sugar, fat and salt are combined rather than by themselves.? This is something called the “bliss point” and companies pay scientists millions of dollars to create this optimal concentration of dopamine stimulating ingredients.? It’s exactly why it’s hard to eat just a few Lays potato chips or Oreos.

There is a logical reason why we may be driven toward sugar.? Starch is long chains of glucose.? Glucose is sugar, and when starch is digested it releases large amounts of glucose into your bloodstream.? If you think about what foods would have contained sugar that our ancestors had access to, there were basically two things; fruit and honey, which were two safe sources of calories.? Sugar is important for athletic performance because when you’re doing high intensity activity fat oxidation can’t really support maximal levels of exertion.? The body uses glycogen for that.

This could be why sugar tastes so good, because high intensity activity was so important for our ancestor to survive certain situations, as well as conducting a successful hunt.

It’s also thought that two thirds of our tongue contain sweet receptors.?

Calorie intake is a fundamental driver (and one of the most critical) of survival and reproductive success.? One of the reasons for this is because when a woman is pregnant, her calorie needs go up.? Also, in childhood, your immune system is a calorie hog.? Infectious disease in non-industrial settings is a huge cause of infant and childhood mortality.? In men, when calories are too low for an extended period of time (in as little as three days), testosterone levels start to drop.? Mother Nature doesn’t believe it’s a good idea to bring a child into the world during a time of famine.

As you can see, there were some pretty good and logical reasons to gorge ourselves at every opportunity thousands of years ago, but as we know, we’re never a few miles or minutes away from high calorie foods.? In fact, it’s easier to find these types of foods (just look at the isles in any gas station) than it is to find whole, nutritious foods.

?Satiety

As you can see from the above charts, choosing the right foods can make a drastic difference in satiety, while also ensuring that we are fueling our bodies with high quality, nutritious foods.?

Carbs can be slightly more satiating than fat and due to the fact that carbs contain a lot less calories per gram than fat (4 grams vs 9 grams, respectively), they may be the better choice.

Eating a small variety of foods keeps you from overeating.? Simplicity is the key, and bland foods won’t reinforce the properties of food that increase dopamine and cause cravings for the same food later.? Our brains just didn’t evolve to handle the massive dopamine spike that happens when you isolate and purify highly refined sugars (sucrose), and basically blast your brain with them.

Sensory Specific Satiety

Just because we become satiated with one type of food doesn’t mean we will be with other types.? What this means is that the more variety of foods on your plate, the more calories you will be able to consume.? There’s evidence to suggest that when you eat a lot of super palatable foods, your brain allows and makes room for a large consumption of them because it perceives them as extremely valuable and desirable.

Different foods have different sensory properties.? Getting full on protein doesn’t mean you won’t still desire some starch or fat, and even some dessert after those.? It’s not just how full you feel, the volume of food or the calories, it’s also about how your brain is perceiving your intake of the specific sensory property of the foods.

Think how much more you can eat at a buffet or how, all of a sudden after you eat your meat, veggies and starch at a restaurant, you’re suddenly able to consume a large dessert when you previously thought you were full.

Our ancestors didn’t build up some large variety of food and have a feast with it.? It usually only consisted of just one or two foods at a time

Factors that affect hunger experience

• Actual amount of calories
• Composition of calories (macro nutrients)
• Water content (causes a stretch stimulus)
• Amount of fiber (how long it takes to get through the digestive tract)
• Appearance rate of nutrients in the bloodstream
• Mouth feel
• Palatability
• Different types of palatability and smells that someone experiences related to their childhood and what they grew up eating

Stress and it’s relation to overeating

High stress levels can cause people to overeat, gain fat (particularly abdominal fat), as well as corresponding deteriorations in metabolic health.? Basically, some people tend to secrete a lot of the stress hormone cortisol when they’re stressed, and some don’t.? Stress causes us to produce cortisol which then travels to the area of the brain called the hypothalamus to reduce Leptin sensitivity.? In short, when this happens, it causes us to overeat and gain fat.

People also “self-medicate” with junk “comfort” foods which dampen the activity of neural networks that are responsible for the feeling of stress, as well as the physical effects of cortisol release.

How can we refrain from overeating?

Just knowing why we have this drive to over consume these types of foods is the first step to fighting obesity and coming up with strategies for managing weight loss.

Strategies that can be employed now that you have an understanding of the brain’s role in what we desire to put in our bodies:

• Control food environment- no tempting snack on the counter or if they are easily accessible, make them foods that require a bit of effort like a bag of unsalted peanuts or pistachios verses a can of salted peanuts.
• Refrain from keeping things that are tempting in your personal environment.
• Quality of food- unrefined as possible and not calorie dense or overly palatable.?
• Limit added fat, just enough to cook with like olive or coconut oil.
• If you have, say a potato, don’t top it with butter or sour cream but maybe a little salt and pepper.? You can just mix the potato with other foods on your plate as well.

It’s not necessarily about making foods boring but keeping our palates from becoming over stimulated.?

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