The Psychology of Weight Loss

The adaptiveness of weight.

Posted Jun 28, 2019

Statistics will tell you that the rates of obesity are increasing. There’s also a lot of good data to show that excess weight is bad for your health. But just because extra weight might be unhealthy, it doesn’t mean that there is something “wrong” with you if you have excess weight.

In fact, gaining weight is a natural consequence of a highly adaptive evolutionary system that developed to ensure the survival of our species. Over the course of our existence, starving to death has been a major threat to human life. In fact, starving to death is not a problem that the human species has solved. As you read this, there are humans somewhere on the planet starving to death.

As a result, our bodies have developed system after system to ensure that we don’t starve to death. For example, research shows that our metabolism slows down when we lose weight, a phenomenon referred to as “metabolic adaptation.” This means that as you lose weight, your metabolism slows down, and it becomes harder to lose more weight. But our bodies don’t just stop at reducing our metabolism to make sure we don’t starve to death. Research shows that food will actually smell better and taste better one year after you lose weight.

Why on earth would your body torture you like this? Well, it thinks it’s just been through famine or a long, terrible winter with no food. Your body is desperate to put the weight back on to make sure you don’t starve to death. You know all those skinny girls in the advertisements—they’re not the ones who could survive a long, hard winter. Individuals who could put on extra pounds whenever food was available are the ones who survived—they are our ancestors.

Not only does your body encourage you to eat, but it also motivates you to eat all the things that are so-called “unhealthy”. Why are we motivated to eat “unhealthy” food? Consider the honey seekers of New Guinea. Members of this tribe climb about forty feet up a tree in order to reach into a beehive while dangling precariously in the air and getting stung. But sugar is so scarce in those parts that it’s worth it.

Let that sink in for a minute: This is the world our body and brain were adapted for, one in which sugar, fat, and salt are rare. Would you want to climb forty feet in the air and get stung by bees just to get a handful of sugar? Of course not! So, your body developed a highly motivating system to make doing so worth it: the reward system of the brain. In fact, the reward system in the brain “lights up” better for sugar than it does cocaine! This is why “unhealthy” food feels good (at least in the short term).

What this means is that bodies that gain weight are doing exactly what they have evolved to do. We’re just not meant to live in an environment where you can ingest your total daily caloric needs in a single meal. It, therefore, should not be surprising about how hard it is to maintain a “healthy” weight. So, if you do carry extra weight, despite everything you’ve been told, there’s nothing wrong with you. Your body is working exactly as millions of years of evolution have shaped it to work! Understanding the “adaptiveness” of weight can help us come up with different skills and better ways to help ourselves and our patients lose weight and maintain it.