PhotoIf you wonder why so many Americans (and other industrialized-world citizens) are getting fat these days, the answer is probably quite simple: human evolution is lagging behind human technology. We live in an industrially and technologically advanced world where food is abundant, yet still have the bodies of Cro-Magnon hunter gatherers living under constant threat of famine.

For example: last April the journal Obesity published a study about late-night snack cravings: namely, why are they so common? If you’re trying to lose weight—or just avoid gaining any—then eating before bedtime is the worst thing you can do, because your sleeping body takes those calories and converts them almost immediately into fat.

Obesity discovered evidence suggesting that our body’s circadian rhythms are naturally inclined to make us feel hungry at night.

Dr. Steven Shea, from the Center for Research on Occupational and Environmental Toxicology at Oregon Health & Science University, wrote: “We found with this study that the internal circadian system also likely plays a role in today's obesity epidemic because it intensifies hunger at night …. it seems likely that the internal circadian system helps with efficient food storage. While this may have been valuable throughout evolution, nowadays it is likely to contribute to the national epidemic of obesity.”

Age of abundance 

PhotoPacking on some extra body fat tonight is a very good idea when you know you might not eat at all tomorrow—and until only a few generations ago, that was the human status quo. Only in an age of abundance, when people’s main calorie-related problem is “We eat too many of them,” does the urge to eat just before bed become fantastically counterproductive.

Of course, this was far from the only study suggesting our own evolutionary history is conspiring to expand our waistlines.

Last month, researchers at Yale suggested that eating low-calorie artificial sweeteners might paradoxically make you fatter than full-calorie sugar—because when your brain tells you “We’re seriously craving some sugar right now,” sugar is the only thing that will satisfy that craving. And, unfortunately, even if you personally are a genius, your brain still isn’t smart enough to figure out “Instead of generating fresh sugar cravings, maybe I should do something with the extra poundage bulging around my owner’s waistline.” 

So when you get annoyed by those late-night snack cravings, just remember: it’s because your brain and body are trying to save you from starving to death. (Which does not make it any easier for us to fit into our old blue jeans, but—well, it’s the thought that counts, right?)  

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