How Good is the Atkins Diet?

A new study, just published in JAMA, compares several popular diets: Atkins, Zone, Ornish, and LEARN (a conventional-wisdom-type diet based on “national guidelines,” according to the paper). The Atkins diet did much better than the other three. The results were quite a bit more positive for Atkins than an earlier comparative study where compliance was poor, weight loss was minimal, and no diet was clearly better than the rest. The Atkins Company, not surprisingly, is pleased with the new study; they have put it in their research library.

Here is what the researchers concluded from their data: “A low-carbohydrate, high-protein, high-fat diet may be considered a feasible alternative recommendation for weight loss” (from the abstract — the meaning of “alternative” is not explained).

However, a graph in the paper (Figure 2 for those of you with access) makes a very important point that the researchers don’t mention: Persons on the Atkins diet weighed more after 12 months on the diet than after 6 months. After 6 months, in other words, the lost weight was coming back. The regain is not small: From Month 6 to Month 12 the Atkins dieters regained about one-quarter of the weight they had lost. At the end of the study (Month 12), they had lost about 10 pounds.

My interpretation is that the Atkins Diet works for two reasons: 1. The food is new. The flavors of the new food are not yet associated with calories. The novelty wears off, of course. This is why some of the lost weight was regained. 2. High-glycemic-index foods (such as bread and potatoes) are eliminated. This produces permanent weight loss, but not a lot. When I started to eat low-glycemic-index foods I lost 6 pounds, which I never regained. A 6-pound loss is not terribly different from the 10 pounds (average) lost by study participants.

In a newspaper article, the study’s lead author mentioned the regain:

As the study progressed, [Christopher Gardner, an assistant professor of medicine at the Stanford Prevention Research Center] said, some dieters put back on some of the weight they had lost early in the year.

That’s misleading. It wasn’t “some dieters” — it was a trend shown by the whole group. But at least he (kinda) mentioned it.