Having a high body mass index (BMI) increases the risk of developing type 2 diabetes but does not increase the chances of a heart attack or an early death, a study has found.
Researchers looked at 4,000 genetically identical twins in Sweden to evaluate the risks associated with obesity.
Professor Peter Nordström, of Umeå University, followed the twins for an average of 12.4 years, looking at whether they suffered a heart attack, were diagnosed with type 2 diabetes or died early.
According to the Daily Mail, he found there were 203 heart attacks (5%) and 550 deaths (13.6%) among the heavier twins.
They had an average BMI of 25.9, edging them into the overweight category.
The leaner twins, who had an average BMI of 23.9, had 209 heart attacks (5.2%) and 633 deaths (15.6%).
The risk of diabetes was greater in the heavier twin.
Professor Nordström said the study revealed a significant association between obesity and diabetes after accounting for genetic factors.
He said interventions to promote weight loss are more effective in reducing the risk of diabetes than the risk of cardiovascular disease and mortality.
The research was published online in the journal JAMA Internal Medicine.