You Are Not What You Eat?

In a recent Wall Street Journal article, Ron Winslow discusses a study on weight gain that is to be published in the Journal of the American Medical Association. Participants in the study, "25 young, healthy men and women," were all fed 1,000 excess calories a day for 56 days as part of either a low-protein, normal or high-protein diet. The amount of carbohydrates was kept constant across all three diets while fat intake varied according to the protein intake of each diet (higher protein diets had lower fat intake and vice versa). As the chart from the article (above) indicates, increases in body fat were the same across all different diets. According to Winslow, this suggests that the amount of excess caloric intake alone affects body fat increases, as opposed to the nutritional content (fat, protein, carbohydrates, etc.) of a diet. However, as the chart also indicates, those consuming a low-protein diet experienced a decrease in lean body mass while those following the normal and high-protein diets experienced an increase. This is suggested to contribute to overall weight gain being significantly lower for those following a low-protein diet. While the study suggests that high protein diets do not prevent increases in body fat, it may lead some to believe they are superior because they support lean body mass. As Dr. Bay, a researcher at Pennington Biomedical Research Center, puts it, "there is no health-related benefit to a reduction in lean body mass," and loss of lean body mass is "not what you want to happen."