Where body fat is stored may matter more than BMI for heart health

In the study, published in Heart, the team used detailed heart and abdominal MRI scans of more than 34,000 UK Biobank Participants to compare three types of body fat: visceral fat around the abdominal organs, fat beneath the skin and fat surrounding the heart. They combined these scans with an artificial intelligence model that estimated each person’s biological heart age using 56 measures of heart structure and function.

The researchers found that people with the same BMI could have very different patterns of body fat and very different levels of cardiovascular risk. Their findings suggest that body fat distribution may help explain why some people develop heart disease while others with a similar BMI do not.

Among the three types of body fat, visceral fat showed the strongest independent association with accelerated heart ageing and future cardiovascular disease. Although fat surrounding the heart was also linked to poorer cardiovascular health, this relationship was largely explained by the amount of visceral fat elsewhere in the body.  

Participants were followed for an average of almost five years after their MRI scans, allowing the researchers to investigate how different patterns of body fat related to future cardiovascular disease. The team also found that associations between visceral fat and heart ageing were generally stronger in men than in women.

Dr. Cynthia Maldonado-Garcia, postdoctoral researcher at Queen Mary University of London and lead author of the study, said: "This research shows that where your body stores fat matters just as much as how much fat you have overall. BMI is useful, but it can't tell us where the fat actually sits. By using MRI scans to see fat location, we can start to explain why some people face higher heart disease risk than others, even when they have the same BMI. In the future, this could help doctors spot high-risk patients more accurately and design prevention plans tailored to the individual."

Dr Zahra Raisi-Estabragh, Senior Clinical Lecturer and Consultant Cardiologist at Queen Mary University of London and senior author of the study, said: “Our findings show that not all body fat carries the same risk. Where fat is stored appears to be particularly important for heart health, with fat around the abdominal organs showing the strongest link to accelerated biological ageing of the heart and future cardiovascular disease.

“BMI remains a useful and practical measure, but it cannot tell us how fat is distributed throughout the body. Our findings suggest that looking beyond BMI could help us better understand why some people develop cardiovascular disease while others with a similar body weight do not.”

The researchers stress that the findings do not mean MRI scans should replace BMI in routine healthcare. Instead, the work improves understanding of how different types of body fat influence cardiovascular ageing and could help inform future research into more personalised ways of assessing cardiovascular risk.