| > The entire purpose of fat is to store excess energy for future use That isn't true. Though it's a primary use, the opening paragraph of the wikipedia article on fat outlines that it actually has many biological functions (and is properly thought of as an organ!): https://en.wikipedia.org/wiki/Adipose_tissue > ... because over human evolution food supply was unreliable enough for this to create an evolutionary advantage. Getting fat from eating a lot of food is completely predictable. Not at all. While fat does have a primary function as an energy reserve, that does not mean that unregulated growth is a simple matter of putting too much energy into the system. After all, just as in nature there are times of famine, there are also times of feast. It would be pretty disadvantageous for animals to have no regulation on their fat growth in times of abundance. Something more has to go wrong to cross the line from "saving for a rainy day" to "killing you". Animals don't eat until they damage their stomachs, do they? Not generally. Why does it make any more sense that they should eat until they damaged their endocrine systems? An interesting counterpoint: bears hibernate. In preparation for doing so, they become fat by eating a lot. Now, they do this, not just any time of the year when food is abundant, but specifically in the fall as they prepare for the winter. Are they just lucky that food happens to be abundant every fall? Or is something else going on? What happens in years of famine? Do they still manage to get fat so they can hibernate? Another interesting counterpoint: Pregnant women eat a lot and put on weight. Why do they do that? Is it because more food is available? Or is something else going on? One last counterpoint. Bodybuilders put on a lot of muscle, which also takes energy, and they eat a ton to support that growth. Why is it that if I eat an extra steak, my flab gets bigger, but when Ahnold eats one, his biceps get bigger? Obesity is dysregulated growth. While growth does require energy, it is in the failed regulation of that growth that you will find the best explanation for the disease. |
I really can't blame you for assuming this, but it actually turns out that food was scarce enough in human history that humans never actually evolved a limit on how much fat we will store. If we keep consuming a caloric surplus the body will keep creating fat to store it. This is the body working as intended. Things would be different if humans had a more reasonable max body fat percentage.
https://en.wikipedia.org/wiki/List_of_heaviest_people