People who are genetically predisposed to storing belly fat, or having an apple-shaped body type, could face a higher risk of type 2 diabetes and heart disease, researchers said Tuesday.
The study in the Journal of the American Medical Association (JAMA) suggests a person's genetic makeup may cause health problems down the road.
"People vary in their distribution of body fat -- some put fat in their belly, which we call abdominal adiposity, and some in their hips and thighs," said senior author Sekar Kathiresan, associate professor of Medicine at Harvard Medical School.
"We tested whether genetic predisposition to abdominal adiposity was associated with the risk for type 2 diabetes and coronary heart disease and found that the answer was a firm 'yes'."
Previous observational studies have uncovered a link between belly fat and type 2 diabetes and heart disease, but fell short of proving cause and effect.
To investigate further, researchers examined six studies conducted from 2007 to 2015, including some 400,000 participants whose genomes were analyzed.
Previous research had identified 48 gene variants associated with waist-to-hip ratio, resulting in a genetic risk score.
They found that people with certain genes that predisposed them to higher waist-to-hip ratio also had higher lipids, insulin, glucose and systolic blood pressure, as well as a higher risk for type 2 diabetes and heart disease.
"These results illustrate the power of using genetics as a method of determining the effects of a characteristic like abdominal adiposity on cardiometabolic outcomes," said lead author Connor Emdin, a researcher at Massachusetts General Hospital.
Since researchers did not find any links between body type, genetic risk score and confounding factors such as diet and smoking, that "provides strong evidence that abdominal adiposity itself contributes to causing type 2 diabetes and heart disease," he added.
Emdin said the findings could one day lead to the development of drugs designed to target belly fat, and perhaps lower the risk of diabetes and heart disease.