The skinny
Virginia Postrel links to a
Reason article debunking a study that touting the low-carb Atkins diet. The study didn't count the 43% of participants who dropped out, and he adds:
Gary Foster of the University of Pennsylvania co-authored a study conducted in virtually the same manner as Westman's. Foster, whose work will soon appear in a major medical journal, provides a simple explanation for the Atkins weight loss. The regimen "gives people a framework to eat fewer calories, since most of the choices in this culture are carbohydrate driven," he says. "Over time people eat fewer calories."
Randy Seeley of the University of Cincinnati co-authored yet another "sister study" with similar results. His explanation is the same as Foster's. Ultimately, Atkins is nothing more than a low-calorie diet in disguise.
Now, I have a personal interest in weight loss, having shed 35 pounds recently myself. I didn't do it by the Atkins diet or anything like it. But I wonder if the article -- and the study -- is asking the right question. People keep asking if such-and-such a diet "works" as if there should be some eating plan out there that would cause everybody who uses it to lose weight. But I doubt such a thing exist, or will ever exist, because the question assumes everybody is the same.
From my own anecdotal evidence, I'd say people have radically different experiences of eating. For instance, my sister, who has always been thin, hits an abrupt shutoff point when she's eaten enough. It doesn't matter how much is left in front of her; if she's full, she loses interest. Me, I can go on for a while and not realize how full I am until later. A July 2001 New Yorker article by Atul Gawande provided medical support for this:
When food enters your stomach and duodenum (the upper portion of the small intestine), it triggers stretch receptors, protein receptors, and fat receptors that signal the hypothalmus to induce stiety. Nothing stimulates the reaction more quickly than fat. Even a small amount, once it reaches the duodenum, will cause a person to stop eating. Still we eat too much fat. How can this be? It turns out that foods can trigger receptors in the mouth which get the hypothalamus to accelerate our intake -- and, again, the most potent stimulant is fat. A little bit on the tongue, and the receptors push us to eat fast, before the gut signals shut us down...Apparently, how heavy one becomes is determined, in part, by how the hypothalamus and the brain stem adjuicate the conflicting signals from the mouth and the gut.
But that's just the beginning of the complications. People also vary in what kinds of foods they like, what time of day they're hungriest (you can divide the world into breakfast eaters and non-breakfast eaters), whether they prefer a few meals or a lot of little snacks, and so on. People also overeat for different reasons. I overate because I had a rather overactive appetite; I would eat a little too much at every meal, and over time it built up. But I also have a friend who claims to barely feel hunger at all, yet overeats because he just enjoys the tastes. Some people get heavier with age because they developed youthful eating habits and never changed. And then there are people who binge when they're under emotional stress, like alcoholics turn to drink.
That is why I never succeeded in losing weight until I essentially designed my own diet. I actually got started two years ago when I signed up for some personal training at my gym. The trainer weighed me, measured me, applied some pincers to various parts of my body, and entered it all into a computer to determine how many calories I needed to maintain my weight, and (by extension) how many I needed to lose weight. He mapped out this whole plan for me, and I took it home and almost immediately started fiddling with it. I pretty soon started ignoring the protein/fat/carbo ratios it called for (which I think was mainly to make sure I didn't malnourish myself, since I was eating less.) I found that I was too hungry with the original calorie count, so I adjusted it upward a bit so it was still below maintenance level. (Also, like a lot of women, I found my appetite varied over the course of the month, and adjusted to that too.) The result was that I lost weight slower. But that was a trade-off I was willing to make.
Basically, I treated the diet as a negotiation between my natural appetite and my desire to lose weight. With a bit of trial and error, I found a reasonable comprimise. But the trouble with the diet culture today is that hardly anyone treats it like that. There's this Manichean moralism about the whole thing. As a writer in put it in a women's magazine I read years ago, "When you hear women today talk about temptation and sin, guilt and shame, they're likely talking about food." People routinely say they're "being good" when they're sticking to a diet, and "being bad" when they slip.
Of course, most people who say this don't really think of dieting as a moral issue on plane with, say, war with Iraq. But I do think that the language means something real, and that makes eating and dieting so difficult for so many people. For one thing, it leads to the idea I mentioned earlier that there's One True Way to lose weight, instead of taking all the human differences into account. But what makes it even more Manichean, in the true sense of the 3rd-century cult of Mani, is that it regards the bodily appetite as the enemy. Rather than trying to work and negotiate with it as I did, many dieters make a wholesale attack on it. As a result, of course, appetite rebels, and it usually wins.
This exaggerated idea of dieting as self-denial, I think also leads to the dream of a diet with
no self-denial. As Reason puts it, "Our increasingly obese population is desperate for some magical formula to avoid the physiological law that body fat is determined by calories in and calories out." If you consider a diet as a battle between thinness and pleasure, without the possibility of compromise, no wonder.
The Manicheanism also is applied to the food itself. People are forever trying to figure out what foods are "good" and which ones are "bad." Is milk good because it has protein, vitamins and minerals, or bad because it has animal fat? How about peanuts? I was thinking of this when I read a
New York Times article that's been going around the blogosphere about the benefits of moderate drinking. Apparently, evidence of this was suppressed for a while because people didn't want to spread the idea that alcohol is "good." And in excess, of course, it's still extremely bad for you. With food and drink, as with so many other things, it's all about the dosage.
All this dualism has led, I think, to the rigid nature of so many diets. Of course, some people like rigid. I have an uncle who lost 70 pounds on a plan where he weighs all is food, is forbidden to eat flour, and has other weird rules. I couldn't do it, but he's been at it for more than 10 years, so more power to him. But again, one size does
not fit all. I think for a lot of people dieting is like having a mental slavemaster in your ear, telling you you can't make a single mistake or you'll fall into the abyss. No wonder they can't stick to them.
Why the excessive moralism about eating? It might be a certain residual Puritanism in the culture -- the feeling that anything pleasurable, especially fleshly, must be morally suspect. It is as if, being abandoned elsewhere, our Puritanism attaches itself to food. But I also think people are confusing behavior with the motives. Dieting calls for self-control and putting the long term ahead of the short term. Both of these are, to a certain extent, necessary for virtue. But this ignores what the motive is. While it's true that some religious and moral systems see a positive good in taking care of the body (St. Paul would say it's a temple of God, and should not be abused), and gluttony as a sin, most overeating doesn't rise to the level either of gluttony or a health threat. We want to lose weight so we can look good. There's nothing moral about it. It's not immoral, but there's no special virtue to it.
Realizing all this made the whole thing a lot easier for me. But of course, the diet industry stands to lose a lot of money if everybody freelances it like I did.