As obesity rates, measured by body mass index (BMI), continue to rise in the United States, so do the initiatives to help people lose weight, including the introduction of new weight-loss medications. However, a recent systematic review and meta-analysis published in the British Journal of Sports Medicine revealed that cardiorespiratory fitness is a more significant predictor of cardiovascular disease and overall mortality than BMI.
The researchers discovered that individuals who are fit, regardless of their BMI, had similar risks of death from all causes and cardiovascular disease. In contrast, unfit individuals across all BMI categories faced two to three times higher risks of dying from all causes and heart disease compared to fit individuals of normal weight. Notably, obese individuals who are fit had a considerably lower risk of death than unfit individuals of normal weight.
According to Siddhartha Angadi, an associate professor of exercise physiology at the University of Virginia School of Education and Human Development and the study’s lead author, “Fitness is much more critical than fatness when evaluating mortality risk. Our research indicates that those who are obese but fit have a death risk comparable to that of fit individuals with normal weight and almost half of that of unfit individuals with normal weight.”
Angadi further stated, “Exercise goes beyond merely burning calories; it serves as an excellent form of ‘medicine’ that enhances overall health and significantly lowers the risks of cardiovascular disease and mortality for people of all body types.”
The review included 20 studies involving 398,716 adults from various countries, with nearly a third of the participants being female, which is nearly three times the number in earlier studies. Most of the studies defined fitness based on participants’ performance in exercise stress tests (estimated or directly measured VO2max) that placed them above the 20th percentile for their age group.
While obesity is linked to many health issues, weight loss has traditionally been viewed as a solution to mitigate those problems. However, losing weight can be difficult, and the potential for regaining lost weight may bring additional health risks.
Glenn Gaesser, a professor at Arizona State University and co-author of the study, mentioned, “The majority of individuals who lose weight tend to regain it. The cycles of losing and regaining weight, often referred to as yo-yo dieting, are associated with a range of health risks comparable to those associated with obesity itself. By improving cardiorespiratory fitness, individuals may be able to avoid the negative health effects that frequently accompany chronic yo-yo dieting.”
Currently, only about 20% of U.S. adults meet the physical activity recommendations set by the U.S. Department of Health and Human Services, which suggest that adults engage in at least 150 minutes of moderate-intensity physical activity or 75 minutes of vigorous activity weekly, along with muscle-strengthening activities on two days of the week. For those in the lowest 20th percentile of cardiorespiratory fitness, starting any form of aerobic exercise can create a significant positive impact.
Angadi added, “The most substantial decrease in risks associated with all-cause and cardiovascular disease mortality is observed when entirely inactive individuals modestly increase their physical activity levels. Simple activities like brisk walking several times a week to accumulate around 30 minutes each day can achieve this.”
Finally, the researchers emphasize that, given the study’s focus on data from extensive epidemiological studies, it’s time to evaluate the effectiveness of a fitness-centered approach separately, rather than just focusing on weight loss, to enhance health results for obese individuals.
