The epidemic of both obesity and type 2 diabetes is due to environmental factors, but the individuals developing the conditions possess a strong genetic predisposition. Observational surveys and intervention studies have shown that excess body fatness is the major environmental cause of type 2 diabetes, and that even a minor weight loss can prevent its development in high-risk subjects. Maintenance of a healthy body weight in susceptible individuals requires 45–60 minutes physical activity daily, a fat-reduced diet with plenty of fruit, vegetables, whole grain, and lean meat and dairy products, and moderate consumption of calorie containing beverages. The use of table values to predict the glycemic index of meals is of little – if any – value, and the role of a low-glycemic index diet for body weight control is controversial. The replacement of starchy carbohydrates with protein from lean meat and lean dairy products enhances satiety, and facilitate weight control. It is possible that dairy calcium also promotes weight loss, although the mechanism of action remains unclear. A weight loss of 5–10% can be induced in almost all obese patients providing treatment is offered by a professional team consisting of a physician and dieticians or nurses trained to focus on weight loss and maintenance. Whereas increasing daily physical activity and regular exercise does not significantly effect the rate of weight loss in the induction phase, it plays an important role in the weight maintenance phase due to an impact on daily energy expenditure and also to a direct enhancement of insulin sensitivity.
