Study: Fewer Calories Key to Weight Loss

New Study Suggests Caloric Reduction Is Key to Weight Loss Efforts

A new diet study published in the February 26, 2009 issue of the New England Journal of Medicine presents evidence that sheds light on dietary success strategies. Much recent debate with respect to dieting has focused on the kinds of foods and composition of meals eaten, but the two-year study conducted by Harvard researcher Frank Sacks, MD, et al., found that the number of calories consumed may be the most critical component of any diet.

In the study, 811 overweight adults were randomized to one of 4 diets: high-fat, average protein; high-fat, high-protein; low-fat, average protein; or low-fat, high-protein. Each diet contained similar hearth-healthy items. At 6 months, participants in each diet lost an average of 6 kg (7% of initial weight). Although participants did begin to regain weight at about 12 months into the study, by the end of the 2-year period the average weight lost was 4 kg among the 80% of participants who completed the trial.

"Research has looked at whether carbohydrate is more satiating than fat, or whether protein is more satiating than carbohydrates, or whether overeating fat puts more fat in the belly than overeating carbohydrates, etc," says Dr. Sacks. "But where this study is going to be helpful is in saying 40% fat, 20% fat, it doesn't matter. If people can maintain a calorie deficit no matter what type of diet they were on, they're going to lose weight."

Levels of satiety, satisfaction, and group counseling session attendance were similar across all 4 diets and participants improved their lipid-related risk factors and levels of fasting insulin. Another finding was that those who regularly participated in counseling sessions were able to lose more weight than those who did not, with an average weight loss of 0.2 kg per session attended. Possible conclusions from the study include the idea that total amount of calories consumed is more important than the number of calories obtained from carbohydrates or fat, that people who have a dieting program and are committed to it have better odds of success, and that treatment for obesity is a multi-faceted challenge that may require society-wide responses.

Source: 1. Sacks FM, Bray GA, Carey VJ, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates.
N Engl J Med 2009; 360:859-873.

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