Some people turn to high-protein diets in hope of losing weight without the typical dieting hunger pangs and loss of lean muscle mass. But are these diets as healthy as they seem? Maybe not. A study published in Cell Reports found that while high-protein diets may preserve lean muscle mass, they might interfere with the improvement in insulin sensitivity that usually accompanies weight loss—a key to lowering diabetes risk.

For the study, researchers assigned 34 non-diabetic women with obesity, ages 50 to 65, to three different diet groups: the first group ate a low-calorie diet providing 0.8 grams of protein per kilogram of body weight per day (weight loss group); the second group ate the same low-calorie diet but with 1.2 grams of protein per kilogram of body weight per day (high-protein weight loss group); and, the third group was asked to eat their usual diet and to maintain their weight (control group). Researchers measured the women’s weight and markers of insulin sensitivity at the beginning and end of the study, which lasted for around 27 weeks. They found that:

• The weight loss group and the high-protein weight loss group lost about 10% of their body weight compared with the control group.
• The high-protein weight loss group lost about 45% less lean muscle mass compared with the weight loss group.
• In the high-protein weight loss group, insulin sensitivity markers didn’t improve, whereas in the weight loss group, insulin sensitivity markers improved by 25–30%.

These findings suggest that eating high amounts of protein could inhibit improvements in insulin sensitivity related to weight loss. However, it’s important to note that this study was small, and more research is needed to confirm the effects of high-protein diets on metabolism and diabetes risk. In the meantime, if you’re thinking about starting a new diet, work with your doctor to find one that’s a good fit for you.

Source: Cell Reports