We've learned that "healthy" looks different depending on your body shape and type, especially as we've now embraced the body positivity movement. Still, when we think of the stereotypical picture of health, we probably imagine someone who is "in shape." However, a new study may challenge that belief. A systematic review and meta-analysis published in the British Journal of Sports Medicinethis week found that fit people, even when overweight or obese, might be just as healthy as those who have lower body mass indexes (BMIs).
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Researchers found that fit people in all BMI categories didn't have an increased risk of death from cardiovascular disease or any other cause when compared with "normal weight-fit individuals."
On the other hand, those who were unfit were two to three times more likely to die from any cause or cardiovascular disease—regardless of BMI category—when compared with people who were fit and at a normal weight.
"Fitness, it turns out, is far more important than fatness when it comes to mortality risk," Siddhartha Angadi, PhD, associate professor of exercise physiology at the University of Virginia (UVA) School of Education and Human Development and corresponding author of the study, said in a press release. "Our study found that obese fit individuals had a risk of death that was similar to that of normal weight fit individuals and close to one-half that of normal weight unfit individuals."
The researchers reviewed 20 different studies that included a total of 398,716 adults from different countries. People were classified as fit (in most of the studies) if they had an exercise test score above the 20th percentile for their age group. Roughly one-third of the participants were female.
Considering the findings, researchers highlight the importance of exercise—and not just for weight loss or calorie burn.
"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 said in the press release.
If you're not typically active, you can also start slowly to help reap these benefits.
As Angadi explained, "The largest reduction in all-cause and cardiovascular disease mortality risk occurs when completely sedentary individuals increase their physical activity modestly. This could be achieved with activities such as brisk walking several times per week with the goal of accumulating approximately 30 minutes per day."
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Researchers also pointed out that obesity is associated with different health conditions, and weight loss can be beneficial in mitigating that risk. But they conceded that this process is difficult for many, resulting in the "yo-yo effect."
"Most people who lose weight regain it," study co-author Glenn Gaesser, PhD, professor at Arizona State University, added in the release. "Repetitive cycles of losing and gaining weight—yo-yo dieting—is associated with numerous health risks comparable to those of obesity itself. Improving cardiorespiratory fitness may help avoid the adverse health effects associated with chronic yo-yo dieting."
While the yo-yo effect has been puzzling for some time, another recent study identified a potential reason: fat cells actually "remember" being obese.
The study, published in Natureon Nov. 18, examined the yo-yo effect in mice. It found that when overweight mice shed pounds, their fat cells also experienced changes. When the mice started to eat a "high-fat diet" again, they regained weight faster than mice whose cells didn't have these memories.
"The fat cells remember the overweight state and can return to this state more easily," Ferdinand von Meyenn, professor of nutrition and metabolic epigenetics at ETH Zurich, explained in a press release outlining the findings.
Researchers also observed this effect in humans, using fat tissue biopsies from overweight people who'd undergone stomach reduction or gastric bypass surgeries. People whose fat cells had experienced obesity responded to food differently during testing, growing faster by taking in nutrients faster.
Researchers from that study, however, noted that this finding highlights the importance of maintaining a healthy weight.
"It’s precisely because of this memory effect that it’s so important to avoid being overweight in the first place. Because that’s the simplest way to combat the yo-yo phenomenon," von Meyenn said in the release.
