The other day, I was reading an article on the Gawker network about American culture and obesity. The article didn't really stick in my head (which is why I didn't link to it) but one of the comments did. It was someone insisting that all of the medical information indicating that there is a heritable component to obesity, and that it's easier for some people to lose weight than others, is all being completely overstated and overblown by fat people who don't want to admit that they're too lazy to lose weight. His argument was that there couldn't be a genetic element to obesity, because there's no way evolution would select for a trait that made you overweight, because you'd have a hard time escaping predators.
Now, I know that you, my regular audience, is far too intelligent to fall for that line. But on the off-chance that someone is wandering into my blog for the first time and actually believes this, I will explain it to you in simple terms.
For approximately 99.999995% of the 3.5 billion years life has existed on this planet, for approximately 99.999995% of the living beings on this planet, food has been scarce. Starvation has been a real and omnipresent risk for every single living thing for longer than human beings can actually comprehend, and even today, a relatively tiny percentage of a relatively tiny number of species can actually avoid this food scarcity. As a result, life on Earth has spent 3.5 billion years adapting to become the most efficient energy storage machines it is possible to be. Your mind may know that there is food in the store on the corner, but your body is the inheritor of a vast and complex legacy that knows, on a genetic level, that the next meal may not come for days.
Human beings have not adapted to deal well with a super-abundance of food for the same reason that we have not adapted to deal well with leprechaun attacks, or rampaging unicorns. It's just fundamentally something we have never encountered in any meaningful sense. To suggest that somehow primitive Twinkies tempted our proto-hominid ancestors, and that evolution favored the lean and the mean over the mastodon-hide couch potatoes until the modern generation started going to hell in a handbasket, is to be fundamentally ignorant of the basic facts of biology. You know how you can tell this? Because actual evolutionary biologists are telling you.
So let's face that basic fact. Losing weight is something that basic biology makes it hard for many people to do. If you are one of the people for whom it is easy, congratulations. I'm very happy for you. But please don't imagine that this is somehow due to your superior moral fiber, OK? Thanks.