5 Signs You Might Be 'Skinny Fat'

When we hear the word weight, we often relate it to numbers, whether as pounds on a scale or as our body-mass index (BMI). But your weight and BMI don't paint a complete picture. Weight and size do not necessarily determine how healthy a person is. Just because someone has a weight clinically considered normal for their height doesn't mean that person is necessarily healthy.

Sometimes people call this phenomenon "skinny fat," but the scientific terminology is normal-weight obesity. Normal-weight obesity can affect anywhere from 9% to 34% of people and is defined as having a BMI between 18.5 to 24.9 kg/m² with a high percentage of body fat, as was reported in a 2020 study published in PLoS One.

People with normal-weight obesity "look healthy, but when we check them out they have high levels of body fat and inflammation," Ishwarlal Jialal, MD, professor of physiology, metabolism, and pathology and California Northstate University, College of Medicine, and staff endocrinologist at the VA Medical Center, Mather, Calif., told Health. "They're at high risk for diabetes and cardiovascular problems, but you wouldn't know it from their appearance."

Researchers are still teasing out the nuisances of weight as a predictor of disease—and it's no easy task. There are also some people with obesity who are also considered metabolically healthy. In other words, being at a higher weight is not always accompanied by risk factors for diseases like insulin resistance and the hardening of the arteries (atherosclerosis).

These are important findings. Insulin resistance creates high blood sugar levels, which can lead to type 2 diabetes. Atherosclerosis puts people at risk for several diseases including heart attack and stroke.

Getting your blood pressure, cholesterol, and blood sugar levels checked is the only way to know for sure how healthy you are metabolically. But there are some warning signs that may help you determine whether you're at risk for normal-weight obesity. If these characteristics apply to you, talk to your healthcare provider about how you can ensure you're physically fit, both inside and out.

Extra Weight Around Your Waist

How your weight is distributed makes a difference in your risk of disease. Having extra weight around your belly can be dangerous. But keep in mind that the biological male body and female body do not store fat in the same way. The way fat is distributed between the sexes tends to lend bodies with female anatomy more of a "pear" shape and those with male anatomy more of an "apple" shape.

A 2015 study found that people who don't meet the criteria for overweight or obesity but still have excess fat around their middle had an even higher risk of dying early than people who have overweight or obesity. The researchers used a measure called waist-to-hip ratio, which turned out to be a more accurate predictor of death from cardiovascular disease than BMI.

"Fat around the middle is worse than fat anywhere else," Dr. Jialal said. "It's where the damage starts in terms of insulin resistance and inflammatory proteins." And this kind of fat doesn't appear all at once, either, so it's easy to ignore. "It should be a warning sign if you're slowly increasing your belt size or your pants start feeling tighter around the waist, Dr. Jialal added.

Low Lean Muscle Mass

People who do not have overweight or obesity can still have high levels of body fat, especially if they lack lean muscle mass. And if you can't remember the last time you broke a sweat, there's a good chance this could be you.

Getting regular aerobic activity—like brisk walking, cycling, or running—is important for maintaining a healthy heart and healthy lungs. But adding in regular strength training will also help you build muscle, which will rev your metabolism and burn fat.

If you're looking for a no-cost way to increase lean muscle mass, consider push-ups. One study of male participants found that those who were able to do more push-ups were less likely to develop cardiovascular conditions. But even if you don't have male anatomy, it doesn't hurt to build upper body and core strength.

Family History

If a parent or sibling has developed diabetes, heart disease, high blood pressure, or high cholesterol (no matter what that person's size is), you may be genetically predisposed to these conditions, as well. If this is you, talk to your healthcare provider about ways you can avoid health problems that run in your family.

Healthcare providers may suggest following a healthy diet, getting regular physical activity, and not smoking. Exercise and a balanced diet can help you ensure that you are lowering your risk in a healthy way. If you still have risk factors (like high blood pressure or elevated blood sugar) even with a healthy lifestyle, medications may help you keep them under control.

An Unhealthy Diet

Maybe you're able to eat burgers and guzzle sodas without gaining a pound. Or maybe you count your calories, but you fill up on white bread and junk food rather than fruits and veggies. Either way, consuming too much sugar and fat—and not enough vitamins, fiber, and lean protein—can damage your organs and raise your risk for diabetes, heart disease, cancer, and more.

A balanced diet can help lower your risk for these conditions. It will consist mostly of nutrient-rich foods. That means eating your fruits and vegetables, getting enough calcium, and limiting your intake of fried or breaded foods and foods that are high in calories, fat, or added sugars.

Yo-yo dieting, skipping meals, and extreme cleanses can also be associated with normal-weight obesity, Cynthia Sass, RD, Health's contributing nutrition editor, told Health. That's because you pack on body fat when you get hungry and overeat, but you lose muscle mass when you drastically cut calories—a bad combination that wreaks havoc on your health.

Genetics and Older Age

As noted above, BMI isn't a perfect measurement for any group of people. And some research suggests that it may be even less useful as a measure of overall health for certain ethnic groups. For example, a 2016 study reported that resident South Asians are more likely to store excess fat around their internal organs than U.S. race/ethnic groups of the same BMI.

This type of fat that surrounds organs, known as visceral fat, has been associated with metabolic problems and chronic disease. "Genetics are definitely involved in how people store fat, but culture and diet also probably play a role, too," Dr. Jialal said. "And obviously eating healthy and getting exercise is good for everyone, no matter what your risk factors."

An American Journal of Medicine study from 2014 found that older adults should pay less attention to their BMIs. Because we lose muscle as we age, it's common for older people to have high body fat percentages, regardless of weight. Focusing on building muscle mass, rather than worrying about the number on the scale, can help older adults live longer and healthier lives, the study concluded.

The Good News

A 2019 study identified ways people with normal-weight obesity can reduce their risk. This study found that normal-weight obesity, defined by a waist-to-height ratio of more than 0.5 at a normal-weight BMI, puts people at a higher risk of death from cardiometabolic disease. Cardiometabolic disease is a broad category that includes cardiovascular disease, diabetes, and kidney disease.

This study also found that this waist-to-height ratio was a better clinical sign of central obesity than BMI. You can find your waist-to-height ratio by dividing your waist size (measured at the smallest part of your waist, in inches) by your height (in inches). Another conclusion of the study was that making modest changes in diet, like following a Mediterranean diet, and exercising can also reduce one's risk.

A Quick Review

What a "healthy" weight is varies from person to person. Your waist-to-hip ratio may be more important than the numbers on the scale or your BMI. A higher waist-to-hip ratio may be linked to a higher risk of cardiovascular disease and its consequences.

Following a healthy lifestyle is one thing you can do to lower your risk factors. This can be accomplished by getting regular exercise, eating healthy foods, and not smoking. If you have other diseases like high blood pressure or diabetes, it's important to keep them managed as well.

But not all factors can be controlled. If you have a family history of cardiovascular disease or are in an at-risk population, a healthcare provider will be able to tell you what's best for your situation.