<span class=”atwho-inserted” contenteditable=”false” data-atwho-at-query=”@lilac”>@Lilac</span> Evolution is a process, and while that process could account for some extra fat, there is no way it would be a good explanation for the amounts we see today. 50-100 extra pounds of fat is fairly common, in both men and women, and it’s not hard to find someone has something like 200 or more extra pounds. There is no evolutionary benefit to having so much extra fat that reproduction and basic functions like movement are seriously impaired.
If you looked at any of Brad Marshall’s videos, he details the diet that animals switch to when they are trying to pack on weight prior to hibernation. And pack on weight they must, or else death is guaranteed. When gaining this weight, the animals start eating a diet much higher in unsaturated fat (big surprise, I know). Which would indicate that diet, or certain components of the diet, would probably drive fat gain more than “evolution.”
And as Americans have gotten more overweight and obese, PUFA has been increasing in the food supply. We are eating a fattening diet, but hibernation never comes. Here’s a chart from the USDA that shows the PUFA increase from 1909 to 2005. It’s certainly increased in the past 20 years, as hydrogenation and trans fats got demonized. But anything high in “trans fats” was also high in PUFA. Now that the seed oils aren’t being hydrogenated, the people are no longer getting the protective effect of trans fats, and are dealing with a bigger PUFA load.
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