High-protein, low-carb diets are often touted as magic cures for those who want to drop a little (or a lot) of extra weight. The Atkins rave of the early 2000s and the more recent hype around the Paleo lifestyle have driven a high-protein movement that gained momentum with media attention and celebrity endorsements.
Though some research does suggest that high-protein diets lead to weight loss in the short term, the greater body of evidence indicates that in the long term, these diets may do more harm than good.
One recent study of 34 overweight women asked half the group to eat a typical weight-loss diet containing a standard amount of protein and the other half to follow an otherwise identical diet that contained 50 percent more protein than usual. Both groups succeeded in losing 10 percent of their body weight. But the high-protein group showed no increase in insulin sensitivity, a typical benefit of weight loss that can help decrease the risk of developing type 2 diabetes. In other words, the high-protein diet eliminated one of the major favourable side effects of weight loss.
Another much larger study raised even more concerns about the effects of high-protein diets. Researchers in Spain asked over 8,000 men and women – most of whom were already following a Mediterranean diet – to recall, in detail, their daily protein intake. Not only were those who consumed the most protein more likely to gain weight, but they were also twice as likely to die from cardiovascular causes and 48 percent more likely to die from cancer. In an even larger study, in which over 100,000 postmenopausal women were asked to self-report their daily diets, researchers noted that as protein intake increased, the incidence of heart failure doubled…