The study, of nearly 500,000 people who provided data to the UK Biobank, suggests that in both sexes, the waist-to-hip ratio is a better predictor of heart attacks than general obesity, as measured by weight relative to body size using the body mass index (BMI). However, the research suggests women with an ‘apple shape’ are particularly at risk.
‘Our findings show that looking at how fat tissue is distributed in the body – especially in women - can give us more insight into the risk of heart attack than measures of general obesity,’ said Dr Sanne Peters, Research Fellow in Epidemiology at The George Institute for Global Health (Nuffield Department of Women's & Reproductive Health) who led the study.
‘Our findings also suggest that differences in the way women and men store fat may affect their risk of heart disease. Understanding the role sex differences in body fat distribution play in future health problems could lead to sex-specific public-health interventions that could address the global obesity epidemic more effectively.’
Being overweight or obese is a major, and increasingly common, risk factor for chronic diseases including heart attack, diabetes, and stroke, which are leading causes of death and ill-health worldwide. World Health Organisation guidelines suggest that men with waists bigger than 102cm and women with waists bigger than 88cm face a substantially increased risk of metabolic conditions, which include diabetes.
The new research, published in the Journal of the American Heart Association, found that a high BMI was linked to the risk of heart disease in both sexes. However, bigger waists and higher waist-to-hip and waist-to-height ratios in women were 10-20% more strongly linked to the risk of heart attack than a high BMI.
Waist-to-hip ratio was an 18% stronger predictor of heart attack than BMI in women, and a 6% stronger predictor of heart attack in men, which suggests that having more fat around the abdomen in particular has a bigger impact in women, possibly for genetic or biological reasons.
‘We need further research to try to disentangle the different ways women and men store body fat and understand how, and why, this is linked to different health risks,’ said Peters.
The full paper, 'Sex Differences in the Association Between Measures of General and Central Adiposity and the Risk of Myocardial Infarction: Results From the UK Biobank', can be read in the Journal of the American Heart Association.