A report in Nutrition Reviews suggests that high protein weight loss diets can be harmful.  Julie Eisenstein M.D. and colleagues reviewed experimental and epidemiologic data and found that consumption of protein in an amount greater than two to three times the U.S. Recommended Daily Allowance can lead to urinary calcium loss and predispose to bone loss.  High protein diets are very popular diets.  Although they are effective in helping weight loss, they are considered risky.  High protein diets promote weight loss by providing the sensation of satiety and increasing "total energy expenditure by increasing the thermic effect of feeding."  High protein weight loss diets may increase the risk of nephrolithiasis or kidney disease particularly in those with diabetes mellitus, the report says. Studies show that plant-based diets are the best to help weight loss or prevent weight gain or obesity.

Eisenstein, J., Roberts, S. B., Dallal, G. and Saltzman, E. (2002), High-protein Weight-loss Diets: Are They Safe and Do They Work? A Review of the Experimental and Epidemiologic Data. Nutrition Reviews, 60: 189–200. doi: 10.1301/00296640260184264