While it has long been recognised that an ‘apple-shaped’ body is associated with an increased risk of diabetes and heart disease, the new research sheds light on the specific genetics linked to this body shape and the potential mechanisms behind the increased risk.
The findings, published in JAMA: the Journal of the American Medical Association, may help to better identify individuals at risk of developing these conditions and inform their subsequent treatment.
Researchers at the University of Cambridge in the UK studied the genetic profiles of over 600,000 participants from several large UK and international studies.
They identified over 200 genetic variants that predispose people to a higher waist-to-hip ratio, a measure of the ‘apple shaped’ body. Using this data, the researchers identified two specific groups of genetic variants that increased waist-to-hip ratio - one exclusively via lower hip fat and the other exclusively via higher waist (abdominal) fat.
“We found that both of the genetic variants we identified were associated with higher risk of type 2 diabetes and heart attacks,” said Claudia Langenberg from the University of Cambridge.
“The concept of an ‘apple shaped’ figure has been understood for some time but our research considers how this body shape alters fat distribution in the body,” Langenberg said.
“Genetics which specifically change fat distribution by lowering fat storage around the hips increase risk of disease independent of, and in addition to, mechanisms that affect abdominal fat storage,” she said.
Researchers conducted detailed assessments of fat distribution in different regions of the body of 18,000 people using DEXA, a low-intensity X-ray scan that can distinguish body fat, bone composition, muscle and lean mass across the whole body.
They suggest that there is a greater proportion of people in the general population with subtle forms of familial partial lipodystrophy, a rare genetic disorder characterised by the inability to develop fat in the arms, legs and buttocks. Those with this condition often go on to develop diabetes and its cardiovascular complications.
The team hopes that their findings will help to better understand the ways in which fat storage in different body compartments affects metabolic health and leads to disease.
They suggest their work could refine the way we detect and treat people at risk.