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November 24, 2024 — A groundbreaking study published in the British Journal of Sports Medicine challenges the conventional wisdom that weight loss is the most important factor for improving health outcomes. As obesity rates continue to rise in the United States, so too do efforts to promote weight loss, including a new generation of weight-loss medications. However, a recent systematic review and meta-analysis reveal that cardiorespiratory fitness may be a more important predictor of overall health than body mass index (BMI).
The comprehensive analysis of 20 studies involving nearly 400,000 adults found that cardiorespiratory fitness plays a more significant role in predicting cardiovascular disease and mortality risk than BMI. In fact, fit individuals, regardless of their BMI, had similar risks of death from all causes, including cardiovascular disease. By contrast, unfit individuals, even those with a normal weight, faced significantly higher risks of premature death.
“Fitness, it turns out, is far more important than fatness when it comes to mortality risk,” said Siddhartha Angadi, associate professor of exercise physiology at the University of Virginia and corresponding author of the study. “Our research found that obese individuals who were fit had a risk of death similar to that of normal-weight fit individuals and much lower than those who were unfit, regardless of weight.”
Fitness Over Fatness: A Shift in Health Focus
The study suggests that exercise, rather than weight loss, may be a more effective tool for improving health and longevity. For those struggling with obesity, the study found that being fit could substantially reduce the risks associated with obesity-related conditions such as cardiovascular disease, even in the absence of weight loss.
“Exercise is more than just a way to expend calories. It is excellent ‘medicine’ to optimize overall health and can largely reduce the risk of cardiovascular disease and all-cause death for people of all sizes,” Angadi noted.
The researchers analyzed data from 20 studies with a combined total of 398,716 participants from multiple countries. Approximately one-third of the participants were women, a significant increase from previous studies. In these studies, individuals were classified as “fit” if their exercise stress test score (VO2max) was above the 20th percentile for their age group.
The Risks of Weight Cycling and the Benefits of Fitness
The study also sheds light on the risks of “yo-yo dieting,” a cycle of losing and regaining weight. According to Glenn Gaesser, professor at Arizona State University and co-author of the study, weight cycling is associated with health risks comparable to those of obesity itself.
“Most people who lose weight regain it,” Gaesser said. “Repetitive cycles of losing and gaining weight—yo-yo dieting—can have serious long-term health consequences. Improving cardiorespiratory fitness can help mitigate the adverse effects associated with this cycle.”
Current physical activity guidelines recommend that adults perform at least 150 minutes of moderate-intensity exercise per week, or 75 minutes of vigorous exercise, along with muscle-strengthening activities twice a week. For those in the lowest 20th percentile of cardiorespiratory fitness, even modest increases in physical activity can have significant health benefits.
“The largest reductions in mortality risk are seen when sedentary individuals begin any form of aerobic exercise, such as brisk walking,” said Angadi. “Just 30 minutes of walking several times a week can substantially reduce the risk of all-cause and cardiovascular disease mortality.”
A Call for a New Approach to Health
The researchers emphasize that their findings, based on large-scale epidemiological data, highlight the importance of a fitness-based approach to improving health outcomes, particularly for individuals with obesity. They suggest that it may be time to shift the focus away from weight loss and toward promoting fitness as the key to reducing the risks associated with obesity.
“We need to rethink how we approach health and wellness,” said Angadi. “Rather than focusing solely on weight loss, we should prioritize improving physical fitness, which can lead to significant health improvements, regardless of one’s body size.”
This new perspective on health emphasizes the idea that it’s not the number on the scale that matters most, but the strength and endurance of the body. As research continues to evolve, it may be time for health policies and individual wellness strategies to reflect this shift toward fitness over fatness.
For further information, the study can be referenced as:
“Cardiorespiratory fitness, body mass index, and mortality: a systematic review and meta-analysis” by Nathan R. Weeldreyer, Jeison C. De Guzman, Craig Paterson, Jason D. Allen, Glenn A. Gaesser, and Siddhartha S. Angadi, published November 13, 2024, in the British Journal of Sports Medicine.
DOI: 10.1136/bjsports-2024-108748
