Calories In = Calories Out

If you eat more than you burn up for the day, you will gain weight.

If you eat less than you burn up for the day, you will loose weight.

Or in more technical terms, the conclusions of the published study:

Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize.

The Study

In the study 811 overweight adults were randomly assigned to one of four diets with varying percentages of energy derived from fat, protein and carbs. Each of the diets consisted of similar foods and all met guidelines for cardiovascular health.

Participants were followed for a period of 2 years. They were also offered group and individual instruction sessions during this time.

The main outcome measured at the end of 2 years was the change in body weight. Among the 80% of participants who completed the study, the average weight loss was 4 kg (8.8 lbs.). A smaller percentage 14 – 15% experienced a reduction of at least 10% of their initial body weight. This study also found that attendance at group sessions was strongly associated with weight loss.

Resources:

Sacks FM, Bray GA. Feburary 26, 2009. Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates. New England Journal of Medicine. 360:859-873

Parker-Pope T. February 25, 2009. Study Zeroes In on Calories, Not Diet, for Loss: Fewer Calories (Carbs, Protein or Fat ) Are Called Weight Loss Key. New York Times.

Image: Modified Microsoft Clipart.