Dietary Protein Reduction During Isocaloric Conditions Reduces Body Weight in Men With Overweight or Obesity.

Plain-language summary

This study set out to see if cutting protein while keeping calories the same could help men with overweight or obesity lose weight. Seventeen men were randomly assigned to eat either a lower-protein diet (0.9 grams per kilogram of body weight per day) with more carbs or their usual higher-protein diet (1.8 grams per kilogram) for five weeks under tightly controlled conditions. The lower-protein group lost about 2 kg more weight without cutting calories, and their levels of FGF21 (a hormone linked to fat burning) went up. The study suggests that swapping some protein for carbs, even without eating fewer calories, might help with weight loss in men carrying extra weight.

Key findings

• Reducing protein intake to 0.9 g per kg of body weight per day led to a 2 kg weight loss in men with overweight or obesity.
• The lower-protein diet increased plasma FGF21 levels, which were linked to weight loss.
• Fat mass decreased significantly, while lean body mass showed only a slight tendency to drop.