It is well documented that excessive weight gain in younger people increases the risk of diabetes, but recent work indicates that there is a 3-5-fold increase in diabetes for those who gain at least 9 kg (about 20#) after the age of 50 y.o. Of course, that also increases the risk of heart attacks, strokes, blindness, and kidney disease. The weight gain at that age consists mainly of an increase in fat. Thus it is important to lose excess fat and maintain it at a normal level. I have heard reports of a new type of chocolate that dramatically shuts down the appetite, resulting in significant fat and weight loss. It should be available through physicians in the next few months.
See JAMA (click here) 2010;303:2504-12.