Twin global epidemics of obesity and diabetes are out of control and could reduce life expectancy in the future, health experts said on Friday.

Obesity, a major risk factor for diabetes, already affects 300 million people worldwide while an estimated 194 million suffer from diabetes.

By 2025 the number of obese people is expected soar to 333 million.

“I suspect that within a short period of time we will begin to see a reduction in life expectancy because of the twin epidemics,” said Professor Claude Bouchard, president of the International Society for the Study of Obesity (IASO).

He was speaking at the 13th European Congress on Obesity here, being attended by some 2,500 doctors and health experts. Professor Rhys Williams, a vice president of the International Diabetes Federation (IDF), noted that a fall in deaths from cardiovascular disease in the United States is now showing signs of stopping.

He suspects it is due, at least partly, to the obesity epidemic, which is also contributing to rising levels of diabetes and is a risk factor for heart disease and stroke.

“The rise in type 2 diabetes is, in great part, due to weight gain,” said Professor Pierre Lefebvre, president of the IDF.

As many as 80 percent of cases of type 2 diabetes are linked to overweight or obesity, particularly abdominal obesity. The disease was once thought to be limited to adults but obese children are now developing the illness.

In the United States, the prevalence of excess weight and obesity in adolescents has nearly tripled in the past two decades.

In 30 years time, the number of people in the U.S. with diabetes is expected to increase by 57 percent, according to Lefebvre. In some countries in the Middle East and Asia the number will double.

“We are facing a huge, huge, epidemic,” Lefebvre added.

A new report on diabetes by the IDF and the IASO, released at the conference, estimated that at least half of all diabetes cases would be eliminated if weight gain could be prevented.

Even a small weight loss, of about five percent, can decrease or slow down the risk of developing type 2 diabetes and other complications of the illness, such as a raised risk of cardiovascular and kidney disease and some forms of cancer.

“A slight decline can have a beneficial effect on diabetes risk,” said Lefebvre,

The report described the twin epidemics as a global health crisis and stressed the importance of eating a low-fat healthy diet and getting plenty of exercise.

“If left unchecked, the outlook for world health is bleak,” the report concluded.