The statistics are scary enough to make you want to stop eating immediately.

The World Health Organization says in just five years [2015], more than two billion adults will be overweight and 700 million will be classified as obese. Being overweight or obese is an expanding problem even in low and middle income nations.

Less physical activity and foods high in fat and sugar are a recipe for a global epidemic of diabetes, the WHO says.

Dr. David Siscovick of the University of Washington in Seattle is one of the researchers who studied how body composition, the ratio of lean tissue to fat, and increased weight affected the risk of diabetes in more than 4,000 adults, aged 65 and older.

Dr. David Siscovick: "If you were in the upper fifth of the population that we studied, the upper 20 percent of the population in terms of multiple measures of adiposity, you had a four fold increased risk of developing diabetes late in life."

At the beginning of the study, none of the participants had been diagnosed with diabetes. Researchers kept track of their body mass index, waist size, and waist to hip ratio over the next 12 years.

Mary Biggs, University of Washington, Seattle: "Even among adults over the age of 75, having a higher body mass index was still associated with a two-fold increased risk of diabetes."

Men who were borderline obese had a five and a half times higher risk of diabetes than those who were just overweight. For women, the risk was about three and a half times higher. The experts believe this is because men tend to have more belly fat.

As hard as it might be, colleague Mary Biggs says making sure your weight stays at a healthy level is the only way to keep the risk of diabetes down.

Mary Biggs: "The results affirm the importance of weight control during middle age and suggest that weight control remains important into older ages in terms of reducing diabetes risks."

The study was published in the Journal of the American Medical Association.