The Real Science Behind ‘You Are What You Eat’

If I had a dollar for every time my mom sneered “You are what you eat,” as she watched me inhale fake cheese by the pound, I might be able to afford higher quality food. Unfortunately for my bank account, increasing research has shown that what we take in with our mouths we also absorb into our minds.

Our mouths are the entryway to a complicated highway system between our brains and our digestive organs. Believe it or not, our gut harbors more neurons than our spinal cord, coining it the name “the second brain.” Our guts transmit information to our brain through trillions and trillions of bacteria.

A poor diet can result in inflammation and a decreased growth rate of new brain cells, severely impacting our mood. What we eat determines which bacteria exists in our guts. The balance of this bacteria determines our mood, epitomizing the notion that you are, indeed, what you eat.

The relationship between the food we eat and the mood we find ourselves in depend on more than the nutrition label on the back of the package. The time of day, the quantity, the ingredients, and even our attitude towards the food significantly influence how our bodies process it. In other words, you aren’t only what you eat, but how, when, and why you eat as well.

The What: The serotonin theory

Serotonin is a neurotransmitter that is significantly correlated with the regulation of appetite, sleep, memory, sexual desire, and mood elevation. Antidepressants known as SSRIs (selective serotonin reuptake inhibitors) frequently target serotonin levels in the brain. Most of our serotonin, however, is located in our gastrointestinal tract. Scientists have found that the consumption of foods dense in complex carbohydrates and the amino acid tryptophan can increase the levels of serotonin in this gastrointestinal tract. The tryptophan is converted into serotonin as the complex carbohydrates increase its availability.

It is important to note that it is complex, and not simple, carbohydrates that the serotonin theory advocates for. Simple carbohydrates exist in fruits, refined grains, and sweet; they come at the expense of the sugar roller coaster referenced to earlier. Complex carbohydrates, on the other hand, allow for a more consistent release of serotonin without the dramatic insulin spike and consequential sugar crash. Complex carbohydrates exist in beans, oats, whole grains, yams, and lentils. Tryptophan has no subtypes and exists in soy, cocoa powder, cashews, chicken breast, turkey, beef, eggs, and fish.

The How and the Why: The hypothalamus theory

If you feel mentally crappy about that second serving of dessert, chances are you’re going to feel physically crappy too. The hypothalamus is a tiny collection of tissue in the brain that is responsible for translating sensory and emotional experiences into physiological responses. If you indulge in that second cookie with the pure bliss that it deserves, the hypothalamus translates this happy feeling into activation signals that fire up the parts of our gut responsible for metabolizing food and promoting more efficient digestion and calorie burning. Sweet.

On the downside, if that second cookie is accompanied by a sense of guilt and remorse, those negative feelings result in inhibitory signals that can result in slower digestion and a release of toxic by-products into the bloodstream. You even have a higher chance of storing that cookie as body fat because of the decrease in calorie burning efficiency. The same process even applies for fruits and veggies. If you consume your food with a poor attitude, your body is going to have a hard time breaking it down. So, if there was ever an excuse to adopt a “treat yourself” attitude, you’re looking at it.

The What revisited: A positive attitude can only take you so far…

Unfortunately, a sugar overdose is still a sugar overdose no matter how good you feel about it. Foods high in refined sugars such as candy, cake, energy drinks, candies, sugary cereals, and even condiments, can have major consequences. The American Health Association (AHA) suggests that women limit their added sugar intake to 24 grams a day and men limit theirs to 36 grams a day. Exceeding this limit can hurt the brain in a variety of ways:

  • Refined sugar causes inflammation in both the mind and the body. Sugar consumption results in insulin-dense fat cells which release inflammatory messages to the brain, producing a bloated stomach and a bloated (and depressed) brain.
  • Sugar depletes B vitamins that are required to maintain positive moods. B12 and folate, in particular, have been clinically proven to help stop depressive symptoms by producing dopamine. In case a sugar binge does occur, animal products high in B12 such as meat, chicken, fish, cheese and eggs can help replenish lost B vitamins.
  • Our blood sugar level influences our mood; inconsistent blood sugar levels result in inconsistent moods. Eating excessive amounts of sugar produces a rollercoaster of glucose levels in the bloodstream. These inconsistent highs and lows result in fatigue, irritability, dizziness, insomnia, excessive sweating, poor concentration, excessive thirst, and blurred vision. The most effective way to maintain a consistent blood sugar level is to cut out refined sugars as much as possible. Instead, replace regined sugars with natural sugars such as fruits. However, an occasional slip up every now and then never killed anybody.

The When: The circadian rhythm

Our entire lives revolve around a 24-hour internal cycle known as the circadian rhythm.  The circadian rhythm regulates our study, participants were split into two groups. Both groups followed a strict 2,000 calorie diet; the first group consumed all 2,000 calories for breakfast and the other consumed all 2,000 calories for dinner. While the participants in the first group all maintained or lost weight, every single participant in the latter group gained weight. Why? It has to do entirely with metabolism and body temperature.

The second we wake up in the morning, our internal body temperature and metabolic rate start to increase until they hit their peak at noon. As the evening progresses, our metabolism slows down and our internal temperature decreases. Our body does not anticipate a need to burn as much energy, slowing down our digestive system. We start to burn calories and fat slower and less efficiently. Additionally, indulging in high calorie or high sugar snacks late at night can disrupt our sleep pattern and the hormonal regulation that occurs during sleep.

Further research

This is only a snapshot of the information regarding how, what, why, and when you eat influences who you are. For further information, here are some of the most popular books for reading and application.

You are What You Eat Cookbook by Gillian McKeith

Happy Gut by Vincent Pedre

Gillian McKeith’s Food Bible: How to Use Food to Cure What Ails You by Gillian McKeith

The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health by Emeran Mayer 

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