Experts say there's not always a one-size-fits-all approach to a healthy weight.

By Julia Malacoff
May 25, 2017

In case you haven't noticed, there's a growing conversation about whether or not you can be "fat but fit," thanks in part to the body positive movement. And while people often assume that being overweight is automatically bad for your health, research shows that the issue is more complicated than that. (More background here: What's a Healthy Weight Anyway?)

First off, while being obese can up your risk for health problems like heart disease, osteoarthritis, and cancer, data also suggests that not all overweight people have the same level of health risk. A European Heart Journal study showed that those who were obese but had normal blood pressure, blood sugar, and cholesterol numbers were at no greater risk of dying from cancer or heart disease than those in the "normal" BMI range. More recently, a study in the Journal of the American Medical Association found that the healthiest BMI is actually "overweight." Wins for the body-pos community.

But new yet-to-be-published research from the University of Birmingham in the U.K. might be calling "fat but fit" into question, according to the BBC. Those who are obese but metabolically healthy (meaning their blood pressure, blood sugar, cholesterol, and triglyceride levels are within a normal range) are still at a higher risk of developing heart disease, stroke, and heart failure, the researchers said at the European Congress on Obesity.

The large-scale research included more than 3.5 million people and is currently under review for journal publication, which means it's not totally vetted yet. That being said, the findings are significant if they check out. The results could mean that doctors would recommend that obese people lose weight, regardless of whether they're displaying other risk factors or seem to be fit, explains Rishi Caleyachetty, Ph.D., the lead researcher on the project.

This doesn't necessarily discount all the other "fat but fit" research, though. "There's a big difference between being overweight and being obese," says Jennifer Haythe, M.D., an assistant professor at Columbia University. Technically, being overweight means you have a BMI between 25 and 29.9, and being obese means that you have a BMI of 30 or above. "I'm not surprised that the data from this new research shows that the people who fall into the obese category have an increased lifetime risk of cardiovascular disease," notes Dr. Haythe, who always recommends that patients with BMIs in the obese range lose weight for health reasons. On the flip side, she says that health risks associated with being just a little overweight aren't as serious. (For what it's worth, some serious athletes fall into the overweight or even obese category based on their BMI, proving that you shouldn't go by that alone.)

Ultimately, doctors are still torn on the topic. Even though she thinks it's safer for patients to be in the so-called "normal" weight range, Dr. Haythe says people can indeed be both overweight and fit. "You can be overweight, run a marathon, and be in good shape from a cardiovascular standpoint."

And it's not like people at "healthy" weights never get heart disease. "There have been many times that I've diagnosed and treated severe heart disease in someone who runs a lot, is not overweight, is relatively young, and only has a few risk factors," says Hanna K. Gaggin, M.D., M.P.H., a cardiologist at Massachusetts General Hospital.

That's not to say that maintaining a healthy weight is a waste of time. Dr. Gaggin explains that while heart disease risk used to be looked at in a population-based way (as in, basing the risk that someone could get heart disease on the fact that others of the same weight got heart disease), the current approach is becoming much more personal and individualized. There are many factors that combine to determine each individual's heart disease risk, such as diet, fitness level, cholesterol, blood pressure, age, gender, race, and family history. "You need to consider all the details of a person," she adds.

"Given the option, I don't think being overweight is a healthy thing," she says. "But when you compare someone who is overweight and healthy, who exercises and eats well, to someone who is not overweight but does not do those things, then the healthier person is the one with healthier habits." The ideal situation, she notes, would be to be a healthy weight and exercise and eat well, but reality and the ideal don't always match up.

So in the end, it seems a bit premature to call "fat but fit" a myth. After all, heart disease risk is based on a slew of factors, not just the number your see on the scale. Paying attention to your nutrition and exercise habits has benefits (physical and mental!) no matter what your weight.