December 03, 2019
Evolution has made our brain lead us to prefer very caloric food. As it does?

In response to a WHO press release last October 2016, the global prevalence of obesity more than doubled between 1980 and 2014, 11% of men and 15% of women being obese in that last year (more than half a billion adults).

This figure is not worrisome only because of what it means for our body to store large amounts of fluids and fats; In addition, obesity is related to addiction and certain mental disorders.

A fat-oriented brain

Let's do a little experiment. As you read the following list of foods, imagine them as vividly and sharply as possible:
  • Chocolate Donuts
  • Cream buns
  • Ham and cheese pizza
  • Burger overflowing with sauce
  • Soft drink with ice
  • Chocolate milkshake with whipped cream

Does your mouth water when you think about those foods? That powerful flavor, the sweet of a glaze, the salty taste of fried smoked bacon... Don't panic, you're within the norm.

And is that multiple studies show that humans, by genetics, have a preference for fats and sugars. In fact, that preference proved to be an evolutionary advantage for our ancestors by allowing the accumulation of fat in their bodies, ensuring survival in stages where food was scarce.

Times change: overfeeding in fats and sugars

That these foods had a particularly pleasant taste was no coincidence: it indicated the presence of these elements. The organoleptic characteristics that precede them: the smell, texture, taste... were a great wake-up call for their consumption, as is the case today.

However, there is unanimity that currently, the current consumption of sugars and fats is excessive in relation to the current way of life. We are fully aware that an increase in the intake of these two foods linked to prevalent sedentary lifestyle does not do our health a favor. And, surprisingly, it is difficult for many people to balance that intake despite the incidence of multiple diseases such as diabetes, hypertension, hypercholesterolemia or obesity.

So, in the long run, it is so harmful to us to eat fats and sugars. What makes us continue along this line? The answer is in our brains.

The Brain Reward Circuit

Also known as the Hedonic or Pleasure Circuit, it is involved in motivation and the feeling of pleasure. It is composed of:

The ventral tegmental area : It constitutes the central link of the reward circuit since its neurons connect to numerous regions of the brain. Performs the release of dopamine.

The nucleus accumbent : Increases brain dopamine levels.

The prefrontal cortex : directs the planning of cognitively complex behaviors, the expression of personality, the decision-making processes and the appropriateness of appropriate social behavior at all times (among many others).

The pituitary : Releases beta-endorphins and oxytocin, which relieve pain, regulates emotions such as love and positive bonds, among other functions.

What elements activate the brain reward circuit? Among others, love, tobacco, cocaine, marijuana, fats, and sugars stand out. But let's focus on these last two.

The psychological explanation of obesity

The process begins with the intake of foods high in sugar or fat, which stimulates the segregation of oxytocin and dopamine from our brain, which provides feelings of joy, well-being, pleasure and avoidance of discomfort since dopamine participates in a way natural functions such as food or sex.

Thus, after having ingested the donuts we imagined above, our body feels good and the well-known hedonic pleasure is produced, which constitutes a positive reinforcement on the behavior of “eating donuts” (which, we will do again). But dopamine (neurotransmitter) and oxytocin (hormone) have a limited life span, and when they disappear, there are feelings of well-being that human beings so crave going on from anxiety to sadness. The intake begins again and the cycle repeats.

The emergence of food dependence

A phenomenon to take into account in the operation of this circuit, is that dopamine and oxytocin every time disappear before the game and, in addition, the doses tend to decrease, for which, if the same level of excitation is desired as at the beginning, the amount or frequency of food intake should be increased by finally becoming addicted.

This process can be related to the development of obesity, diabetes and the newly incorporated DSMV binge eating disorder.

On the other hand, there are data that uncontrolled intake of sugars and fats has a higher prevalence in individuals suffering from obesity compared to normal-weight individuals, but specifically in the obese group, which occurs more frequently in depressed individuals and/or anxious.

Do fats and sugars act as an exhaust pump to tense situations? The research suggests that, in fact, moments of stress and situations that generate negative feelings lead these individuals to make high fat and sugar intakes to feel temporarily well, more after reducing the level of dopamine, they feel anxious and guilty again for the lack of control shown or for having ignored their dietary guidelines.


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