In a study of identical twins in Sweden, researchers found that twins who are heavier were not at increased risk of heart attack or death when compared to their corresponding twin.
However, having a larger body mass index was associated with increased risk for diabetes, according to the study in JAMA Internal Medicine.
The study was conducted between March 1998 and January 2003, with follow-ups occurring through December 2013. Swedish researchers compared the risk of heart attack, death and diabetes in the pairs of twins.
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By the end of the study, there were 203 heart attacks and 550 deaths among the heavier twins (who had an average BMI of 25.9). Meanwhile, there were 209 heart attacks and 633 deaths in the leaner twins (average BMI of 23.9).
They did find an increased risk of diabetes in the heavier twins, however.
"The association between obesity and diabetes was significantly stronger than the association with CVD [cardiovascular disease] and death," the study concludes. "This finding may indicate that interventions to promote weight loss are more effective in reducing the risk of diabetes than the risk of CVD and mortality."