MedWire News: Diets that are high in protein and low in glycemic index effectively minimize weight regain and promote further weight loss in obese patients after a successful weight-loss diet, a study suggests.

Among overweight adults who had successfully lost at least 8% of their initial body weight on a low calorie 8-week diet (800 kcal [3.3 MJ] per day), those who then followed a high-protein, low-glycemic index diet for 26 weeks regained almost 1 kg less in weight than those assigned to a diet low in protein with a high glycemic index.

They were also more likely to achieve an additional weight loss of more than 5% of their baseline body weight, compared with other dietary groups over this time period.

Thomas Larsen (University of Copenhagen, Denmark) and colleagues randomly assigned 773 overweight adults from eight European countries, who were aged an average of 41 years and had achieved the targeted 8% weight loss, to one of five dietary groups.

The diets were either low in protein (13% of total energy consumed) with a low glycemic index, low in protein with a high glycemic index, high in protein (25% of total energy consumed) with a low glycemic index, high in protein and high in glycemic index, or a control diet.

Participants were instructed to maintain their weight-loss during this phase, allowing the team to assess the ability of each diet to regulate body weight.

Writing in the New England Journal of Medicine, the researchers report that during the weight maintenance period, study completion rates were higher in the high-protein and low-glycemic index groups, compared with the low-protein, high-glycemic index group at 26.4% and 25.6% versus 37.4%, respectively, and weight regain was 0.93 and 0.95 kg less, respectively.

Furthermore, participants on a high-protein or low-glycemic index diet were 2.0 or 2.5-times more likely to achieve an additional weight loss of more than 5% of their body weight compared with those in the low-protein group or on a diet with a higher glycemic index, respectively.

The team says that these results indicate that even modest increases in dietary protein or a modest reduction in glycemic index are sufficient to minimize weight regain and promote further weight loss in obese patients after a successful weight-loss diet.

In an accompanying editorial, David Ludwig and Cara Ebbeling, from Harvard Medical School in Boston, Massachusetts, USA, said: "A diet that could effectively prevent weight regain over the long term would have major public health significance."

They add that the completion rates among the low-glycemic index groups provide compelling evidence of the practicality of low-glycemic index diets.

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