You may know that carrying extra pounds in your midsection, even if your overall weight seems fine, comes with risks for your heart health and metabolism. A new study investigated the question, how widespread is the issue, and how significant are the risks?
“normal” body mass index (BMI) combined with abdominal obesity — a mix linked to conditions like high blood pressure, diabetes, high cholesterol, and high triglycerides.
“[Our study] highlights that where you store fat matters more than how much you weigh,” says study author Kedir Ahmed, PhD, an epidemiologist and health data scientist at the Rural Health Research Institute at Charles Sturt University in Australia.
‘Normal-Weight Abdominal Obesity’ Is Common Worldwide
For the study, researchers used cross-sectional data (meaning the information was collected from participants just once, rather than over time) from the World Health Organization (WHO). They looked at chronic disease risk factors for more than 471,000 adults from 91 countries.
The data suggest that the global prevalence of abdominal obesity overall is roughly 45 percent, with nearly 22 percent having a “normal” BMI.
Some of the factors connected to unhealthy levels of belly fat were:
- Higher education level
- Unemployment
- Eating fewer than the recommended number of fruit and vegetable servings per day
- Physically inactivity
In some cases, these factors varied by region.
In addition, the combination of having a normal BMI and excess belly fat was tied to higher risks of the following cardiometabolic conditions (meaning they impact the heart and metabolism):
“We were surprised to find that a large number of people with normal BMI are actually at high risk of cardiometabolic conditions because of excess fat around their abdominal organs,” says Dr. Ahmed. “Our study is the first to show, using globally large sample size data, that normal-weight abdominal obesity is common in every world region and consistently linked to major cardiometabolic risks.”
The authors acknowledge that because the data only captured a snapshot in time, the findings don’t prove that belly fat directly causes any of these health conditions, only that they’re strongly linked.
What Is Belly Fat, and Who Gets It?
Researchers define belly fat (also called abdominal, stomach, or visceral fat) as extra weight that’s centered around your midsection.
While some belly fat is a normal part of everyone’s body composition, too much can be harmful for a number of reasons, Ahmed says.
“Excess visceral fat surrounds internal organs and is metabolically active, releasing hormones and inflammatory substances that disrupt normal metabolism. This can lead to insulin resistance, abnormal cholesterol levels, high blood pressure, and impaired glucose regulation,” he explains.
A variety of factors, including diet, exercise, age, and genetics, can influence who gets belly fat, though researchers are still studying how these elements contribute to body weight distribution.
“We don’t fully understand this, but there are differences by sex, and there may also be differences in genetic predisposition. What we do know is that the abdominal obesity phenotype [a body type predisposed to store fat in the belly] is associated with the highest metabolic and cardiovascular risk,” says Chiadi E. Ndumele, MD, PhD, a cardiology professor and director of obesity and cardiometabolic research at the Johns Hopkins University School of Medicine in Baltimore, who wasn’t involved in the study.
While it’s not possible to drastically change your body type, the good news is that belly fat can be lessened to some extent, says Adrienne Youdim, MD, an internist who specializes in obesity medicine, medical weight loss, and nutrition in Beverly Hills, California.
“Visceral fat is actually highly responsive to lifestyle interventions like low-calorie Mediterranean-style diet and exercise. While fat cells can shrink, they don’t actually die off — but the effect of ‘shrinkage’ of these cells does have positive cardiometabolic health benefits,” says Dr. Youdim.
Why BMI and Waist Size Together May Be a Better Measure of Health
- Underweight: less than 18.5
- Normal: 18.5 to 24.9
- Overweight: 25 to 29.9
- Obesity: 30 or greater
Experts have historically used BMI to define clinical weight categories and assess obesity-related health risks. But in recent years, some medical organizations have advised against using BMI by itself to diagnose obesity — in part because BMI doesn’t account for different factors like body type and fat percentage across population groups, which means it may not accurately reflect true risk.
That’s where waist circumference comes in. This measurement takes belly fat into account, helping to predict the risk of potential health complications by assessing waist size.
This study defined a normal BMI the same as the CDC (18.5 to 24.9), but it defined belly as a waist circumference of at least 80 centimeters (about 31 inches) for women and at least 94 centimeters (37 inches) for men.
This definition differs from U.S. guidelines, which define belly fat as a waist circumference greater than 35 inches for women and 40 inches.
This may have had an implication on the results, as Dr. Ndumele notes that the “conservative threshold for ‘high’ waist circumference may not be similarly applicable across all regions and populations,” he says.
How to Getting Rid of Extra Fat Around the Middle
Experts recommend targeting belly fat the same way you would excess weight in general: diet and exercise.
But as Youdim points out, abdominal obesity is not always widely regarded as a risk factor for disease — so it’s important for new findings like these to support the role of waist circumference in heart health and metabolism.
“This data has the potential to affirm risk and therefore motivate normal weight individuals with abdominal obesity to take lifestyle recommendations more seriously,” she says.
“The risk of cardiometabolic disease goes beyond BMI and the number on the scale — and that everyone has something to gain in terms of health benefits when we engage in lifestyle modifications, including dietary changes and physical activity.”
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