You think you’ve done a wonderful job with your health.
You stand on the scale, and your numbers look great. At a time when so many are obese, your BMI is exactly where it should be. You’ve succeeded where so many others have failed.
You pat yourself on the back.
And then you suffer a heart attack 2 months later. How on earth did this happen?
A new study shows us why weight alone doesn’t give us the whole picture. We shouldn’t just rely on body mass index when assessing our health and fitness.
If we don’t pair our BMI with an additional, crucial metric, we could still be at a heightened risk of a heart attack or stroke — and not even know it.
Too often, unfortunately, doctors forget to check it in their clinic (myself included sometimes). But it’s a metric you can measure easily yourself at home. And I’ll explain how later in this article.
But let’s start by unpacking what slips through the cracks when we’re looking at BMI alone.
Table of Contents
- BMI and Health Risks
- Visceral Fat and Health Risks
- The New Study
- How to Measure Your Risk
- References
BMI and Health Risks
There’s a very good reason we pay attention to BMI. It’s been linked with a host of negative health outcomes, from type 2 diabetes to heart attacks and strokes.
Consider, for example, a meta-analysis looking at the relationship between overweight and obesity and the risk of developing type 2 diabetes. Compared to those with normal weight, the risk was a sobering 7 times as high for those whose BMIs were in the obese range [1].
Deaths linked to heart disease are 2 to 3 times more likely with a BMI equal to or over 35 [2].
But what’s the linkage? How does excess weight connect to negative health outcomes? It’s complex, and there are several mechanisms at play. But one of the most important is the way extra fat drives inflammation.
Stored fat isn’t just passively waiting for when it might be needed as a source of energy. It actually pumps out inflammatory compounds. This leads to elevated levels of inflammatory markers in the blood of people who are overweight.
Researchers have found that the adipose tissue of lean individuals predominantly secretes anti-inflammatory markers, while in obese individuals, more pro-inflammatory markers are secreted. Individuals that are overweight and obese have altered serum levels of inflammatory cytokines such as tumor necrosis factor-alpha (TNF-𝛼), C-reactive protein (CRP), interleukins (IL-6, IL-18), resistin, and visfatin.
And the evidence is increasingly pointing to chronic inflammation as a key driver of conditions like heart disease [3].
Visceral Fat and Health Risks
But there’s a surprising finding that’s come into focus recently. Not all fat is created equal. And that’s why we need this other metric in addition to BMI.
Let me explain this. The fat we notice most easily is the kind stored just under our skin. That’s called subcutaneous fat. But then there’s visceral fat. It’s stored deeper inside, in the spaces surrounding your heart, liver, intestines, and other organs. It’s often called belly fat [4].
Interestingly, subcutaneous fat doesn’t seem to link in the same way with things like type 2 diabetes. On the other hand, visceral fat is strongly linked to it. A standard deviation increase in visceral adipose tissue mass increases the odds of insulin resistance by 80% [5].
Similarly, the chronic inflammation associated with obesity is primarily driven by visceral fat [6].
This is why BMI alone doesn’t tell us everything we need to know. It’s a number that represents the ratio of our weight to our height squared, using kilograms and meters. Suppose our weight is 70 kg (or about 155 pounds) and our height is 1.75 meters (or about 5 foot 9). Our BMI would be 22.86. And that’s in the normal weight range.
But it’s possible for someone to have a normal BMI number while also having excess visceral fat.
I knew a guy who used to joke about his “beer belly.” Maybe you know someone like this, too. He was basically lean everywhere — except his stomach.
And, in men particularly, that’s usually because of excess visceral fat [7].
The New Study
And this raises a crucial question. What kind of risks are associated with a situation like this — where BMI is normal but significant visceral fat is present?
That’s where a new study comes in. Because this was one of the questions the researchers set out to answer [8].
They looked at a comprehensive data set from the World Health Organization. It included information drawn from surveys in 91 countries between 2000 and 2020. In total, there were about 470,000 participants [8].
They zeroed in on those with normal weight according to BMI, which is 18.5 to 24.9, but with high waist circumference. For women, that means 80 cm and above. For men, the figure is 94 cm or more [8].
And it’s this metric that’s so crucial to check in addition to BMI, but it’s too often forgotten about. It’s a convenient indicator of the amount of visceral fat a person has.
Within this particular study group — again, people with normal BMI — they looked to see how blood pressure, type 2 diabetes, total cholesterol, and triglycerides related to waist circumference [8].
Here’s what they discovered. Having a normal BMI but elevated visceral fat, indicated by a high waist circumference, was associated with significantly worse health markers than in those without a high waist circumference.
Specifically:
- A 29% higher chance of high blood pressure
- An 81% higher chance of type 2 diabetes
- A 40% greater risk of high total cholesterol
- A 56% increase in high triglycerides [8]
And the data revealed something else. This combination of normal weight and high visceral fat is common. They found that about 1 in 5 adults in the global dataset they looked at fit this description [8].
The researchers point out that this means we have a big problem on our hands. Because like I mentioned, waist circumference is often forgotten about, and most global guidelines rely on BMI as the primary way in clinical practice to assess risk related to obesity [8].
This means that we have to take charge of our own health and measure our waist circumference ourselves — otherwise, we might still be at risk without realizing it.
How to Measure Your Risk
So how do we do it? And how should we interpret the numbers?
The measurement is simple and can be done at home, but it’s crucial that we measure in the right place. Otherwise, the resulting numbers aren’t going to be accurate. So here’s the correct procedure.
While standing, locate the very top of your hip bone at your side. This is the level where you want to measure, using a flexible tape measure. It’s helpful to look in a mirror to make sure you’re holding the tape measure level all the way around your body. Take the measurement at the end of a normal breath.
Researchers have found that checking your waist circumference at home is about as accurate as having a technician check it in a clinical setting [9].
Now that you’ve got a measurement, how do you interpret it?
If your BMI is in the normal range (18.5 to 24.9), then use the thresholds from earlier in this article:
- Women: ≥80 cm (31 inches)
-
Men: ≥94 cm (37 inches) [8]
If your waist circumference is at or above these numbers, then you may be in the group that the study found to have elevated cardiometabolic risk — despite having a normal BMI [8].
References
1. https://pubmed.ncbi.nlm.nih.gov/20493574/
2. https://www.mdpi.com/2073-4409/10/3/629
3. https://www.jacc.org/doi/10.1016/j.jacc.2025.08.047
4. https://my.clevelandclinic.org/health/diseases/24147-visceral-fat
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC4038351/
6. https://www.ahajournals.org/doi/10.1161/CIRCRESAHA.125.327146
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC6906176/
8. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2840296
