Reward Theory

I need to read and think more, but I have been struck by the “reward theory” of obesity: I have long been convinced that obesity is not a primarily a matter of faulty will in some individuals, nor of an intrinsic human propensity to store fat in good times – neither of those explanations holds up well under scrutiny. No, the prime mover must be something in the environment that overrides the homeostatic regulators. At first I was convinced that refined carbohydrates were the villain, and I still eye them with suspicion: the idea being that sugars and starches incite insulin resistance, and make fat cells reluctant to release their energy, so that I become hungry despite the fact that my body actually has plenty on hand – the cellular cupboards are full of food, but they're all locked.

This story certainly explains much more than the stories I believed when I was younger. It explain why I got so voraciously hungry when I had been eating copiously, for instance, something the primitive calories in / calories out theory didn't explain at all: and it explained why low-glycemic foods had no appeal at all, no matter how hungry I was. It was all very well for people to say that I couldn't really be hungry if I didn't want to eat my salad: but that was untrue. The truth of the matter was that the salad was completely irrelevant to my hunger: I could have eaten quarts and quarts of greens without making a dent in it. Eating that stuff did nothing to sate my craving for cookies or potato chips. I had far more luck with low-carb diets than I had ever had with the officially sanctioned low-fat diets of my youth. A low carb diet worked for weeks, and had an astonishing effect on my appetite. For the first time in my life, I could forget to eat: lunchtime would simply go by, unnoticed.

But the cravings for my favorite foods would grow on me, waiting for some moment when I was emotionally low or needy, or had let myself become really hungry. Then they'd pounce, and suddenly I was off on a huge binge: I wouldn't be able to rein myself in for days. They'd start with something that actually was low-carb – pepperoni, say, or something heavily salted or smoked. And once the bets were obviously off, I'd move on to the things I loved most of all: the ice cream, the potato chips, the cookies.

Now along comes the reward theory, which, as I understand it, goes like this: foods that are unnaturally rewarding – that is, that are tastier than anything a human being would ever have come across a hundred thousand years ago – have the same effect we were attributing to insulin resistance, though by a different mechanism: in the presence of these foods, or perhaps in the presence of just the thought of them, the ordinary satiety feedback loops are somehow interrupted, and the body doesn't release its fat stores properly, and we become ravenously hungry – not for just anything, but for those specific foods that make our reward centers light up like a Christmas tree. We will eat these things till we injure ourselves.

Apparently the problem is not just one of overeating, though of course we do that too. The problem is the tastiness itself. It would make us fat even if we didn't overeat. This is bizarre, but an experiment by John Glendinning et al appears to demonstrate it. (See Stephen Guyanet's blog for a more intelligible summary of the experiment. It's really quite astonishing.)

Now, this does not necessarily tell me what to do. There is not necessarily any way to undo the damage that artificially tasty foods have done to my hunger-satiety regulation. The obvious first thing to try, is simply to eat plain foods and to stay away sight, sound, or thought of the things I crave: not at all an easy thing to do in a world filled with diabolically clever advertising and fast food drive-up windows. But I'm giving it a shot, and the meditative discipline I've acquired should help: I have a lot of experience with training my attention. I'll let you know how it goes.