Abdominal fat increases health risks, even with a normal BMI

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Abdominal fat increases health risks, even with a normal BMI

You may know that carrying extra pounds in your midsection, even if your overall weight seems OK, carries risks for your heart health and metabolism. A new study has addressed the question of how big is the problem and how significant are the risks?

New research suggests that more than one in five adults worldwide suffer
“Normal” body mass index (BMI) associated with abdominal obesity – a mix linked to conditions such as high blood pressure, diabetes, high cholesterol and high triglycerides.

“[Our study] highlights that where you store fat matters more than your weight,” 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 information was collected from participants only once, rather than over time) from the World Health Organization (WHO). They examined chronic disease risk factors in more than 471,000 adults from 91 countries.

Data suggests that the global prevalence of abdominal obesity is around 45 percent, with almost 22 percent having a “normal” BMI.

Some of the factors linked to unhealthy levels of abdominal fat were:

Higher education level
Unemployment
Eating fewer than the recommended number of servings of fruits and vegetables per day
Physical inactivity

In some cases, these factors varied by region.

Additionally, the combination of a normal BMI and excess abdominal fat was linked to higher risks of the following cardiometabolic diseases (meaning they impact the heart and metabolism):

“We were surprised to find that a large number of people with normal BMIs are actually at high risk of cardiometabolic disorders due to excess fat around their abdominal organs,” says Dr. Ahmed. “Our study is the first to show, using data from a large global sample, that normal-weight abdominal obesity is common in all regions of the world and consistently linked to major cardiometabolic risks.”

The authors acknowledge that because the data only captured a snapshot in time, the results do not prove that abdominal fat directly causes any of these health problems, just that they are strongly linked.

What is belly fat and who gets it?

Researchers define belly fat (also called abdominal, abdominal, or visceral fat) as extra weight centered around your abdomen.

While a little belly fat is a normal part of everyone’s body composition, too much of it 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.

Various factors, including diet, exercise, age and genetics, can influence the distribution of abdominal fat, although researchers are still studying how these contribute to body weight distribution.

“We don’t completely understand this, but there are differences by sex, and there may also be differences in genetic predisposition. What we do know is that the phenotype of abdominal obesity [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, professor of cardiology and director of obesity and cardiometabolic research at Johns Hopkins University School of Medicine in Baltimore, who was not involved in the study.

While it’s not possible to drastically change your body type, the good news is that belly fat can be reduced to some extent, says Adrienne Youdim, MD, an internist specializing in obesity medicine, medical weight loss, and nutrition in Beverly Hills, California.

“Visceral fat is actually very responsive to lifestyle interventions, such as a low-calorie Mediterranean-style diet and exercise. Although fat cells can shrink, they don’t actually die – but the effect of ‘shrinking’ these cells has positive cardiometabolic health benefits,” explains Dr. Youdim.

Why BMI and waist circumference may be a better measure of health

Body mass index is a measurement comparing weight to height. The Centers for Disease Control and Prevention (CDC) gives the following parameters for BMI ranges:

Underweight: less than 18.5
Normal: 18.5 to 24.9
Overweight: 25 to 29.9
Obesity: 30 or more

Experts have historically used BMI to define clinical weight categories and assess the health risks of obesity. But in recent years, some medical organizations have advised against using BMI alone to diagnose obesity – in part because BMI does not take into account different factors such as body type and fat percentage in population groups, meaning it may not accurately reflect true risk.

This is where the waistline comes into play. This measurement takes into account abdominal fat, helping to predict the risk of potential health complications by assessing waist circumference.

This study defined a normal BMI the same way as the CDC (18.5 to 24.9), but it defined midriff 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 abdominal 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 a ‘high’ waist circumference may not be equally applicable across all regions and populations,” he says.

How to get rid of excess fat in the middle

Experts recommend targeting belly fat the same way you would target excess weight in general: diet and exercise.

But as Youdim points out, abdominal obesity is not always widely considered a risk factor for disease. So it’s important that new findings like these support the role of waist circumference in heart health and metabolism.

“These data have the potential to confirm risk and therefore motivate normal-weight people 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 everyone has something to gain in terms of health benefits when we engage in lifestyle modifications, including dietary changes and physical activity.”