New Study Says Fitness Level Matters More Than Weight When It Comes to Health

In the new meta-analysis, researchers found that those with higher cardiorespiratory fitness levels had significant protection from cardiovascular disease and other mortality risks, no matter what BMI category they fell into. In fact, those classified as “obese” in the BMI chart but were considered fit had much lower risk of death compared to “normal” weight, unfit participants.

“The takeaway message of our study is that from a health perspective, the risks of being unfit are far worse than the risks associated with carrying extra weight,” said lead author Siddhartha Angadi, Ph.D., associate professor in the department of kinesiology at the University of Virginia. “Unfit individuals, regardless of whether they’re considered normal weight, overweight, or obese, had a two- to three-fold greater risk of mortality compared to fit individuals across weight categories. This study builds on a large body of research over the past three decades that underscores the importance of fitness over fatness.”

In this review, researchers did attempt to overcome some methodological shortcomings of previous studies, which tended to lack female representation, he told Runner’s World. Even with that adjustment, the results still held.

Although BMI probably won’t be scuttled anytime soon, Angadi said that in an ideal world, exercise capacity would be a far better way to gauge health risks, and should even be considered as a “vital sign,” similar to blood pressure, pulse rate, and temperature.

Unfortunately, though, cardio fitness is not a simple measurement to obtain because it requires a cardiorespiratory exercise test that assesses VO2 max, or at least a traditional stress test that can estimate that number.

Your smartwatch will also probably give you an estimate of VO2 max. But Angadi said the issue with these devices is the algorithm tends to overestimate VO2 in relatively unfit individuals and underestimate it in fit individuals, because it’s not based on gas exchange measurements and relies more on heart rate. So your watch obviously won’t offer a clinical-level picture of your health or be able to predict health events.

However, if you’re using a watch and tracking your workouts—and running regularly—chances are you’re on the right track for protecting your heart and avoiding chronic disease. Plus, simply creating more awareness around the importance of fitness over bodyweight could be helpful for the general population, Angadi added.

In terms of how an individual can increase cardiorespiratory fitness level, that’s tricky to answer because thresholds vary by age and sex, said Angadi. But following the American College of Sports Medicine guidelines for physical activity offers a good start, with 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous aerobic activity per week. (Also, check out our tips for increasing VO2 max.)

“As always, it’s a good idea to consult with your physician before embarking on an exercise program, especially if you have a history of chronic disease,” he added.