Research says hidden fat can damage your heart even if you look fit

Harmful benefits of hidden fat in your body (Picture Credit: Pexels)

You might think you’re in fine shape—steady weight, decent diet, nothing frightening in the mirror. Yet under the surface, an unknown threat could be working against your heart. Scientists at McMaster University have revealed that the real danger may not lie in what’s visible, but in hidden fat deep inside the body. Their research suggests that this unseen fat, nestled around organs and the liver, may be sabotaging artery health, even in the seemingly fit.

The new study, published recently in Communications Medicine, focuses on visceral and liver fat, types long linked with diabetes and high blood pressure, but now shown to directly harm arteries too. By using advanced MRI scans on more than 33,000 adults from Canada and the UK, the McMaster team discovered that people with higher levels of these hidden fats had thicker, more clogged carotid arteries—the very vessels that carry blood to the brain. It revealed a greater risk of stroke and heart attack, even for those with healthy cholesterol or blood pressure readings.

For decades, the Body Mass Index has been treated as the gold standard for judging obesity and heart risk. But the lead researcher Dr. Russell de Souza explains, “Even after adjusting for cholesterol, blood pressure and lifestyle, visceral and liver fat still contributed to artery damage.”
The message is clear: a “normal” BMI doesn’t guarantee a healthy heart. Fat stored around organs behaves differently—it’s metabolically active and stirs inflammation that quietly wears down artery walls. It’s the kind of fat you can’t pinch, but it can still hurt you.

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Here’s what the study uncovered:

Over 33,000 adults studied: Participants from Canada and the UK underwent detailed MRI scans.

Visceral fat most harmful: Strongly linked to artery thickening and plaque build-up.

Liver fat still risky: A smaller, but still important, contributor to heart strain.

Risk persists even in the fit: Effects remained after accounting for exercise, diet, and other habits.

BMI no longer enough: Imaging offers a clearer view of true cardiovascular danger.

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Dr. Sonia Anand, one of the study’s senior authors, says the findings are a “wake-up call” for doctors and the public alike. “You can’t always tell by looking at someone whether they carry this dangerous fat,” she explains. “It’s why we need to rethink obesity and cardiovascular risk.” Supported by major Canadian health institutions, the research suggests clinicians to look beyond the scales and tape measure. For those in midlife especially, it’s a reminder that good health isn’t always skin-deep. Sometimes, the real danger is hidden right under it.

FAQs on harmful effects of hidden fat:

1. What is hidden fat, and where is it found?

Hidden fat, or visceral fat, is the fat stored deep inside the abdomen, surrounding internal organs like the liver, pancreas, and intestines. Unlike subcutaneous fat (the fat under your skin), it isn’t visible but can be more dangerous to your health.

2. Why is hidden fat considered harmful?

Visceral fat releases inflammatory substances and hormones that can interfere with normal body functions, increasing the risk of conditions such as heart disease, type 2 diabetes, stroke, and certain cancers.

3. Can a person with a normal weight still have too much hidden fat?

Yes. Even people who appear slim can have high levels of visceral fat, a condition sometimes called "TOFI" (Thin Outside, Fat Inside). Poor diet, lack of exercise, and stress can lead to this buildup.

4. How can I tell if I have excess hidden fat?
It’s not visible, but indicators include a large waist circumference (over 40 inches for men and 35 inches for women), low physical activity, or a diet high in processed foods. Medical imaging like MRI or CT scans can measure it accurately.

5. How can I reduce hidden fat?

You can lower visceral fat through regular aerobic exercise (like brisk walking or cycling), strength training, a balanced diet rich in fiber and low in added sugars, adequate sleep, and stress management.

Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for a specific health diagnosis