High-Carb and High-Protein Diets Both Effective in Maintaining Weight-Loss

People who have recently lost weight may be happy to learn that high−carbohydrate and high−protein diets work equally well when it comes to maintaining the loss. However, the researchers found that there were slight differences in the blood pressures of participants on the respective diets.

Some findings have suggested that high−protein diets may be more effective at helping people actually shed pounds. But the team, led by Elizabeth A. Delbridge, wished to determine whether there were also differences in the effects of the diets on the “elusive” weight maintenance phase and on blood pressure.

Most people gained back very little of the weight they had lost – only about four pounds, on average. There were no statistically significant differences in weight gain between the two groups.

Delbridge and colleagues at the Heidelberg Repatriation Hospital followed 141 women and men who had lost 36 pounds, on average, by cutting calories over a period of three months. The team assigned half of the participants to a high−carb diet and half to a low−carb/high−protein diet for the next year. Those on the high−carb diet were asked to keep their protein intake to 15% of their total calories; the high−protein maintainers kept their protein intake at 30%. Participants were also instructed to keep their fat intake to a maximum of 30%.

Most people gained back very little of the weight they had lost – only about four pounds, on average. There were no statistically significant differences in weight gain between the two groups, which suggests that both diets were equally effective at helping the participants keep off the pounds. However, the high−carb maintainers had a hard time sustaining their high carbohydrate intake while keeping their protein intake low: they managed to keep protein to about 22% of their calories, which was still significantly less than the high−protein group.

Interestingly, there were some differences in how the diets affected heart heath. Though both groups had enjoyed the benefits of falling blood pressure while they lost weight, the average blood pressure of those in the high−carbohydrate group crept back up during the maintenance phase. Those in the high−protein group maintained their lower blood pressure throughout the study.

The researchers conclude by saying that “[t]he results indicate that the protein or carbohydrate content of the diet has no effect on successful weight−loss maintenance,” but that “dietary treatment…was a significant factor in systolic blood pressure change and in favor of the [high−protein] diet.” The results certainly offer some food for thought for those of us trying to maintain a recent weight loss.

The study was published in the November 2009 issue of the American Journal of Clinical Nutrition.