Dietary treatment and long-term weight loss and maintenance in type 2 diabetes.

Increasing body weight, particularly abdominal weight, is associated with increasing risk for type 2 diabetes, and 80% of people with type 2 diabetes are overweight or obese. Weight loss and maintenance are challenging in the obese population without diabetes, and data suggest that this may be more difficult in obese people with diabetes. Various weight-loss strategies with follow-up for at least 1 year have been evaluated in people with diabetes with mixed results. Diet is most effective in promoting initial weight loss. Energy restriction will improve glycemic control within days of initiation, independent of weight loss. There is deterioration of the effects of dietary therapy on glycemic control over time, even with partial weight maintenance, because of the relaxation of energy restriction. Diet composition has little effect on glycemic control independent of total calories. Very-low-calorie diets lead to better initial weight loss and glycemic control but yield no better long-term results than more moderate treatment. The initial results from studies using prepared meals and liquid meal replacements show that weight loss and glycemic control are comparable with conventional dietary treatment. Comprehensive lifestyle therapies, involving diet, exercise, and behavioral modification, can lead to weight losses of approximately 2 to 10 kg over 10 to 20 weeks, with regain over 1 year of one-third to one-half of weight initially lost. The net improvement on glycemic control is usually small 1 year after weight loss. Creative strategies using these and other modalities are needed to improve long-term weight loss, weight maintenance, and glycemic control in patients with type 2 diabetes. Greater efforts in primary prevention are also needed because of the increasing prevalence of obesity and type 2 diabetes.