New findings reveal a quiet threat from hidden fat
A recent study led by researchers at McMaster University has unveiled a troubling link between hidden fat inside the abdomen and liver and damage to arteries, even in people who appear healthy. Published in Communications Medicine, the research challenges the traditional reliance on body-mass index (BMI) as the sole marker of obesity and cardiovascular risk.
What is “skinny fat” and why it matters
Scientists describe a condition where individuals have normal or near-normal weight but carry excess visceral fat (fat around the internal organs) and hepatic fat (fat stored in the liver). These fat stores are metabolically active and can contribute to inflammation, insulin resistance, and arterial changes over time. The new work adds to a growing understanding that body composition — not just total weight — matters for heart health.
How the study was conducted
Researchers analyzed data from more than 33,000 adults across two large cohorts: Canada’s Canadian Alliance for Healthy Hearts and Minds (CAHHM) and the UK Biobank. They used advanced magnetic resonance imaging (MRI) to quantify visceral and liver fat and to assess carotid artery health, focusing on the arteries in the neck that supply blood to the brain.
The carotid arteries are crucial: narrowing or plaque buildup here is a strong predictor of stroke and heart attack. By comparing fat distribution with artery health, the team could isolate the impact of hidden fat while adjusting for familiar risk factors such as cholesterol, blood pressure, smoking, and physical activity.
Key findings: fat distribution matters beyond BMI
The study found that visceral fat consistently correlated with carotid plaque formation and thickening of the arterial wall. Hepatic fat also showed a significant, though weaker, association with artery changes. Importantly, these associations persisted even after accounting for lifestyle and metabolic risk factors, underscoring that hidden fat independently contributes to artery damage.
“This study shows that even after accounting for traditional cardiovascular risk factors, visceral and liver fat still contribute to artery damage,” said Russell de Souza, co-lead author and associate professor at McMaster. He emphasizes that the findings serve as a wake-up call for clinicians and the public alike.
Clinical and public health implications
The results suggest a shift in how we assess obesity and cardiovascular risk. Clinicians may need to move beyond BMI and waist measurements and consider imaging-based assessments of fat distribution when evaluating a patient’s heart risk. For middle-aged adults in particular, hidden fat can quietly elevate the chances of stroke and heart disease, even in those who do not look overweight.
Sonia Anand, the study’s corresponding author and a vascular medicine specialist, highlights the challenge: “You can’t always tell by looking at someone whether they have visceral or liver fat. This fat is metabolically active and dangerous; it’s linked to inflammation and artery damage even in people who aren’t visibly overweight.” This recognition pushes for personalized risk assessment and targeted lifestyle or medical interventions when hidden fat is detected.
<h2 What comes next for research and clinical practice
Future work may explore how to identify individuals at risk for “skinny fat”–related artery damage using non-invasive imaging more widely, or how interventions such as diet, exercise, and medications influence visceral and hepatic fat and, in turn, carotid artery health. In the meantime, the study reinforces the message that weight alone is a blunt instrument for cardiovascular risk and that hidden fat deserves greater attention in both clinical settings and public health messaging.
Practical takeaways for readers
- Recognize that normal weight does not guarantee healthy arteries; hidden fat matters.
- Discuss with your clinician whether imaging-based assessments could help evaluate your cardiovascular risk, especially if you have risk factors or a family history.
- Adopt lifestyle changes known to reduce visceral and liver fat, including balanced nutrition, regular aerobic and resistance exercise, and adherence to a heart-healthy pattern.
