Since two-thirds of American adults are currently overweight or obese, we would all like to be able to help patients choose the “best” diet. The list of choices and categories is lengthy, with vocal advocates for the Atkins diet, the Zone diet, South Beach diet, Jenny Craig, Ornish, etc. Of course, were any of these diets sufficiently effective and easily adopted that they could gain widespread advocacy, we wouldn’t be faced with such an obesity epidemic in the first place! So, apparently there is no “simple answer.” Among the choices we have, then, which one might be the best?

Johnston et al performed a meta-analysis of weight loss trials (n = 48 trials and 7286 subjects), including the above-mentioned diets. Diets were categorized further as low carbohydrate or low fat.

Although there were measurable statistical differences between diets, they were of dubious clinical significance. For instance, at 12-month follow-up, low-carbohydrate diets were associated with a mean weight reduction of 7.99 kg vs 7.27 kg on low-fat diets. Within-group diet differences — e.g., comparing Atkins and Zone diets, both of which are categorized as low carbohydrate — favored Atkins, but these differences were also very small (< 2 kg at 6 months).

Because of the modest outcome differences between diets, the authors conclude that whatever diet the patient can best adhere to should be recommended.