A new study from McMaster University has found that hidden fat deep inside the body—specifically around the organs and in the liver—can silently harm the arteries, even in people who seem healthy.
This research challenges the common belief that body-mass index (BMI) is the best way to measure obesity and health risk.
The study, published in the journal Communications Medicine, shows that two types of fat—visceral fat (around the organs) and liver fat—can increase the risk of heart problems.
These fats have already been linked to type 2 diabetes and high blood pressure, but their impact on artery health was less clear until now.
Using advanced MRI scans and health data from more than 33,000 adults in Canada and the UK, the researchers discovered that these hidden fats are linked to thickening and clogging of the carotid arteries.
These arteries, found in the neck, carry blood to the brain. When they become narrowed, the risk of stroke and heart attack increases.
Professor Russell de Souza, co-lead author of the study, explained that even after accounting for usual heart disease risk factors like high blood pressure and cholesterol, these hidden fats still had a damaging effect on the arteries.
De Souza, who works in McMaster’s Department of Health Research Methods and is part of the Center for Metabolism, Obesity and Diabetes Research, said this is a wake-up call for doctors and the public.
The research team included Marie Pigeyre, associate professor in the Department of Medicine at McMaster, and Sonia Anand, a vascular medicine specialist at Hamilton Health Sciences.
They used information from two large health databases: the Canadian Alliance for Healthy Hearts and Minds and the UK Biobank. These sources helped them measure fat levels and artery health using MRI scans.
Their findings showed that visceral fat is closely connected to artery wall thickening and plaque buildup, which are both signs of artery damage. Liver fat had a weaker but still important effect. These results held true even after considering other lifestyle and health factors.
This study has big implications. It suggests that doctors should not rely only on BMI or waist size to understand someone’s risk for heart disease. Instead, imaging tools that show fat distribution may be more accurate. For people in their 40s and 50s, it’s a reminder that just looking thin doesn’t always mean you’re healthy inside.
Sonia Anand pointed out that this kind of fat is dangerous because it causes inflammation and harms the arteries, even if a person doesn’t appear overweight. That’s why it’s important to rethink how we measure obesity and assess heart health risks.
If you care about liver health, please read studies about Healthy liver, happy life: new advice for keeping your liver in top shape and findings of Ibuprofen may have significant impact on the liver.
For more about liver health, please read studies about Fatty liver disease linked to severe infections and findings of A new drug for weight loss and liver health.
The study is published in Communications Medicine.
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