A lot of people find they can lose excess weight reasonably effectively. However, maintaining that weight loss can be another matter. It’s not uncommon for the pounds that have been shed to slowly return, often with a bit of additional interest.
The reasons for failure are varied, but they include a slide back to less healthy eating and the fact that caloric restriction can lead to slower metabolism. The chronic, long-term failure of weight-loss diets has led some doctors and scientists to explore this problem.
Studies have found that higher-protein diets may have some advantages regarding weight-loss maintenance or fat loss. In one study, individuals were put on a low-calorie diet for a month [1]. Individuals were then split into two groups, one of which had their diet supplemented with 30 grams of protein each day for a 6-month period.
The protein-supplemented group regained less than 2 pounds compared to 6.6 pounds in the other group. However, none of the weight regained in the protein-supplemented group came from fat. This was not true for the other group. Higher protein intake was also associated with a reduction in waist circumference, compared to a gain in the other group.
In another study [2], obese individuals were put on a very low-calorie diet for five to six weeks. After this, individuals were instructed to eat a low-fat diet. Some of the individuals supplemented their diet with carbohydrate (in the form of maltodextrin), while others supplemented their diet with protein (50 grams of casein or whey protein each day). Individuals could eat as much of their new diet as they liked for a period of 12 weeks, at which point they were assessed.
At the end of the study, those supplemented with protein lost an average of 5 pounds more than the carb-supplemented individuals. This lost weight was almost entirely of fat.
Other research had individuals eat either a higher protein (1.6 grams of protein per kilogram of body weight per day) or lower protein (0.8 grams of protein per kilogram of body weight per day) for a year [3]. The first four months was designed to provide individuals with a calorie deficit of 500 calories a day, and for the following eight months, the calorie intake was designed for weight maintenance.
At the end of the year, while weight loss was not significantly different between the two groups, fat loss was. Those on the higher protein diet did better. As a group, they had improved body composition (more lean body mass and less fat) compared to those eating the lower-protein diet.
This last finding—improved body composition—is important. When people lose weight, some of this can be muscle, and this is not a good thing. Higher protein diets can reduce the loss of lean mass during weight loss [4].
Overall, there is good evidence that higher-protein diets help weight loss maintenance and lead to improvements in body composition.
References:
1. McAuley KA, et al. Comparison of High-Fat and High-Protein Diets With a High-Carbohydrate Diet in Insulin-Resistant Obese Women. Diabetologia, 2005; 48(1): 8–16
2. Claessens M, et al. The Effect of a Low-Fat, High-Protein, or High-Carbohydrate ad Libitum Diet on Weight Loss Maintenance and Metabolic Risk Factors. International Journal of Obesity (London), 2009; 33(3): 296–304
3. Layman DK, et al. A Moderate-Protein Diet Produces Sustained Weight Loss and Long-Term Changes in Body Composition and Blood Lipids in Obese Adults. Journal of Nutrition, 2009; 139: 514–521
4. Krieger JW, et al. Effects of Variation in Protein and Carbohydrate Intake on Body Mass and Composition During Energy Restriction: a Meta-Regression 1. American Journal of Clinical Nutrition, 2006; 83(2): 260–274
Dr. John Briffa is a London-based physician and health writer with an interest in nutrition and natural medicine. His Web site is Drbriffa.com
