Carrying excess weight may have a greater impact on the risk for diabetes than it does on the risk for heart disease or early death, a new study has found.
To look at the effect of obesity independent of genetics, Swedish researchers followed 4,046 pairs of identical twins whose average age was 58. One of the twins was overweight, and the other was not. Since identical twins have the same genes, their weight difference could not be attributed to genetics. The study is in JAMA Internal Medicine.
After accounting for physical activity, smoking and educational level, the researchers found that having a higher body mass index, or B.M.I. — even among those in the obese range of 30 or higher — was not associated with an increased risk for heart attack or death. But a high B.M.I. was associated with an increased risk for diabetes.
“Based on these results, the association between obesity and cardiovascular disease is explained by genetic, not environmental, factors,” said the lead author, Peter Nordstrom, a professor of geriatric medicine at Umea University. “Unfortunately, this also means that environmental factors that reduce obesity do not reduce the risk of cardiovascular disease or death. But they most certainly decrease the risk for diabetes.”