"People with a normal weight but a fat belly have more chance of heart problems than people without a fat belly, even if they are obese according to BMI (body mass index)," said study author Jose Medina-Inojosa from the Mayo Clinic in Minnesota, US.
‘Belly fat, even in people who are not otherwise overweight, is bad for the heart.’
"This body shape indicates a sedentary lifestyle, low muscle mass, and eating too many refined carbohydrates," Medina-Inojosa said.
BMI, which is weight relative to height in kg/metre square, is used to categorise adults as underweight, normal weight, overweight or obese. However, BMI does not account for the amount and distribution of fat and muscle.
Central obesity is a store of excess fat around the middle of the body and is a marker of abnormal fat distribution.
This study tested the hypothesis that people with normal weight and central obesity would have more heart problems than people with normal weight and normal fat distribution.
From 1997 to 2000, the study enrolled nearly 1,700 people aged 45 years or older in the US.
Participants underwent a clinical examination and measurements were taken of weight, height, waist circumference and hip circumference.
Patients were followed-up from 2000 to 2016 for the occurrence of major adverse cardiovascular events such as as heart attack, stroke, and death from cardiovascular causes.
Participants with a normal BMI (18.5-24.9 kg/metre square) and central obesity had an approximately two-fold higher long-term risk of heart problems compared to participants without central obesity, regardless of their BMI, the study said.
" If you have central obesity the target will be waist loss rather than weight loss," Medina-Inojosa said.
"Exercise more, decrease sedentary time by taking the stairs or getting off the train one stop early and walking, increase your muscle mass with strength and resistance training, and cut out refined carbohydrates," he added.