Real Food for Real People
A groundless beef with the Atkins diet.
The diet wars are back. A new study, funded by the National Institutes of Health and published in the Journal of the American Medical Association, compares four diets: Atkins (very low carbohydrate, high fat), LEARN (low fat), Ornish (very low fat), and the Zone (low carb). The participants were 311 fat women aged 25 to 50, randomly assigned to one diet or another. According to the Wall Street Journal, women on Atkins "lost the most weight. But there's one catch—the women didn't really stick to the diet." The study's lead author, Christopher Gardner of Stanford University, concludes: "Is this a vindication of Atkins? No, because they weren't really following Atkins."
Now, wait a muffin-pickin' minute. There are plenty of caveats worth noting about this study. But the fact that participants didn't stick to their regimens, as the diet gurus who lost to Atkins are pointing out in every available forum, isn't one of them. Unless you plan on jailing people and sliding food under the door, their ability and willingness to adhere to your diet are crucial factors in its effectiveness. If they're too weak or stupid to follow the formula, stop telling them to buy it.
According to the study, "Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months, and mean 12-month weight loss was significantly different between the Atkins and Zone diets." Furthermore, "At 12 months, secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups." In short, Atkins did no harm and slightly more good.
The study has its shortcomings. If you aren't female, fat, and 25 to 50, the findings may not apply to you. The average weight loss in the Atkins group was only 10 pounds, so the differences among diet outcomes were small. The study lasted only a year, so it didn't measure weight gain or health problems down the road. Nor did it measure effects on kidneys, bone density, or cancer. All four groups regained some weight in the second half of the year, and according to the authors, the trends "suggest that longer follow-up would likely have resulted in progressively diminished group differences" among the diets.
The participants clearly cheated. In theory, Atkins restricts you to 50 grams of carbs a day. By the study's end, the average Atkins dieter was nearly tripling that. The Zone tells you to get 30 percent of your calories from protein and only 40 percent from carbs, but the average Zone dieter never met the protein quota or obeyed the carb limit. Ornish forbids you to get more than 10 percent of your calories from fat, but the Ornish dieters tripled that. LEARN dieters ate 20 percent of their calories in the form of saturated fat, twice what they were supposed to. This, mind you, is what the participants admitted in phone interviews. Imagine how much more they concealed.
The losing gurus have pounced on this, arguing that it discredits the study. "People didn't really follow the diet I recommend," complains Dr. Dean Ornish, founder of the Ornish diet. Of Atkins, he sniffs, "It's a lot easier to follow a diet that tells you to eat bacon and brie than to eat predominantly fruits and vegetables." Dr. Barry Sears, architect of the Zone diet, scoffs that "what the subjects ate in the JAMA study had no relationship to any of the diet programs that were supposedly being tested. ... In fact, the amount of carbohydrates consumed on the 'Atkins Diet' during the study was almost identical to the recommendations of the Zone Diet, which explains why 'Atkins' had the most favorable results." Sears maintains (subscription required), in the Journal's words, that "to really understand which diet is most effective, the eating plans need to be studied under highly controlled conditions."
Will Saletan covers science, technology, and politics for Slate and says a lot of things that get him in trouble.
Illustration by Mark Alan Stamaty.