A new study from McMaster University warns that even people with a normal body weight may not be truly healthy inside. Researchers found that fat hidden deep in the abdomen and liver can silently damage arteries, increasing the risk of heart disease and stroke — even in individuals who appear slim.
Published in Communications Medicine, this research overturns decades of trust in body mass index (BMI) as a reliable indicator of heart and metabolic health.
Study Overview: Beyond BMI to Real Cardiac Risk
The research, led by Dr. Russell de Souza and Professor Sonia Anand, analyzed MRI scans and health data from over 33,000 adults in Canada and the UK. These participants came from the Canadian Alliance for Healthy Hearts and Minds (CAHHM) and the UK Biobank.
Even after considering traditional risk factors like cholesterol, blood pressure, and smoking, visceral and liver fat were still closely linked to carotid artery thickening — an early sign of cardiovascular disease.
“Even people with a normal BMI can harbor dangerous internal fat,” explained Dr. de Souza. “These invisible fat deposits quietly accelerate artery damage.”
Visceral and Liver Fat: The Silent Artery Killers
Unlike the fat under the skin, visceral and liver fats are metabolically active. They release inflammatory molecules that gradually erode artery walls and reduce blood flow to vital organs.
“This kind of fat is metabolically dangerous,” said Dr. Sonia Anand. “It causes inflammation and artery damage even in those who look slim. That’s why relying only on BMI can be misleading.”
Rethinking BMI: Why the Scale Doesn’t Tell the Whole Story
BMI has long been the standard for measuring “healthy weight.” However, it cannot distinguish between muscle, subcutaneous fat, and deep organ fat.
According to this study, nearly 60 percent of adults with normal BMI may still carry harmful levels of hidden fat. These individuals, often called “metabolically obese normal-weight” or “skinny fat,” are at similar risk for artery damage as visibly overweight people.
Experts now urge doctors to combine BMI with waist-to-height ratios or imaging scans for better health assessments.
“The Scale Can Deceive You, but Your Arteries Don’t Lie”
Even when lifestyle factors such as diet and exercise were considered, visceral fat remained a strong predictor of artery thickening.
“Visceral fat acts like an organ of its own,” said Dr. de Souza. “It produces chemicals that fuel inflammation and vascular aging.”
This aligns with findings from Harvard and Massachusetts General Hospital, which advocate updating obesity classifications to include metabolic and imaging indicators. Such updates could double obesity diagnoses in older adults, allowing for earlier prevention and treatment.
What This Means for Heart Health
The study sends a clear message: BMI alone cannot reveal true heart risk. Millions who appear healthy by the scale may still face hidden threats.
Doctors are encouraged to use advanced imaging, blood metabolic markers, or waist measurements to identify risk early.
“If imaging isn’t available, waist-to-height ratios and lifestyle data are useful,” said Dr. Anand. “The goal is early detection and preventive action.”
Practical Tips to Reduce Hidden Fat
- Eat anti-inflammatory foods: Choose whole grains, fruits, vegetables, lean proteins, and healthy fats.
- Exercise regularly: Aerobic activities like walking, jogging, and cycling reduce deep abdominal fat.
- Cut refined sugars and alcohol: These contribute to liver fat buildup.
- Manage stress and sleep: Poor sleep and stress increase hormonal imbalance and fat accumulation.
- Request a health check-up: If you’re slim but have a family history of heart disease or diabetes, ask for metabolic screening.
Q&A: Understanding the Study’s Implications
Q: Can someone with a normal BMI still have dangerous fat levels?
A: Yes. Even thin individuals can carry metabolically active visceral fat that raises heart and stroke risks.
Q: How can hidden fat be measured accurately?
A: MRI scans or waist-to-height ratios reveal internal fat distribution better than BMI.
Q: Is visible belly fat always a warning sign?
A: Not always. Subcutaneous fat is less harmful than deep visceral fat, which causes inflammation.
Q: Can diet and exercise reverse hidden fat?
A: Yes. Regular workouts and a balanced diet can significantly reduce visceral and liver fat within a few months.
Conclusion: Rethinking “Healthy”
The McMaster study delivers a powerful reminder: true health goes beyond appearance and BMI. Hidden visceral and liver fat silently damage arteries long before symptoms arise.
“The scale can deceive you,” said Dr. de Souza, “but your arteries don’t lie. Real health lies beneath the surface.”
By embracing better screening, nutrition, exercise, and awareness, we can uncover—and defeat—the silent epidemic of hidden fat before it strikes.
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Disclaimer
The information provided in this article is for general informational purposes only and should not be considered medical advice. Always consult a qualified physician or healthcare professional before starting any new health practice, treatment, or following the tips mentioned here.
