For better health and a longer life, exercise is more important than losing weight, especially if you’re overweight or obese, according to an interesting review of the links between fitness, weight, heart health and longevity, published this year. past.
The study, which analyzed the results of hundreds of previous studies on weight loss and exercise in men and women, found that obese people typically reduce their risk of heart disease and premature death by working out much more than losing weight or dieting.
The review adds to the evidence that most people can be healthy at any weight, if they are also active enough.
I’ve written often about the science of exercise and weight loss, much of which is, frankly, off-putting if your goal is to lose weight. This latest research overwhelmingly shows that people who start exercising rarely lose much weight, or none at all, unless they also substantially reduce their food intake.
Exercise alone burns very few calories, in general, to help with weight reduction. We also tend to compensate for some of the meager caloric expenditure of exercise by eating more afterwards or moving less, or unconsciously slowing down our bodies’ metabolic operations to reduce overall daily energy expenditure.
​Glenn Gaesser, professor of exercise physiology at Arizona State University in Phoenix, USA, is well-versed in the inadequacy of exercise for fat loss. For decades he has studied the effects of physical activity on people’s body composition and metabolism, as well as their endurance, with a particular focus on obese people. Much of his previous research highlighted the futility of exercise for losing weight.
In a 2015 experiment he supervised, for example, 81 overweight, sedentary women began a routine of walking three times a week for 30 minutes. After 12 weeks, some of them lost some body fat, but 55 gained weight.
In another study by Dr. Gaesser, however, people who are overweight, obese and with significant health conditions, including high blood pressure, low cholesterol profiles or insulin resistance — a marker for type 2 diabetes — have shown considerable improvements in these conditions after they started exercising, losing weight or not.
Seeing these results, Gaesser began to wonder if fitness could allow overweight people to enjoy good metabolic health, regardless of their body mass number, and potentially live as long as thinner people — or even longer, if people thin people are out of shape.
So, in the new study, which was published this month in iScience, he and his colleague Siddhartha Angadi, professor of education and kinesiology at the University of Virginia in Charlottesville, began searching databases for previous studies related to diet, exercise, fitness. , metabolic health and longevity.
They were especially interested in meta-analyses, which pool and analyze data from multiple previous studies, allowing researchers to analyze results from many more people than in most individual weight loss or exercise studies, which tend to be small-scale. .
They ended up with over 200 meta-analyses and relevant individual studies. So they set out to see what all this research, which included tens of thousands of mostly obese men and women, indicated about the relative benefits of losing weight or getting in shape for improving metabolism and longevity. In fact, they asked if someone who is heavy gains more health by losing weight or by getting up and moving.
They realized that the competition was not tight. “In direct comparison, the magnitude of benefit was much greater with improved fitness than with weight loss,” said Dr. Gaesser.
As a whole, the studies they cite show that sedentary, obese men and women who start exercising and improve their physical shape can reduce their risk of premature death by up to 30% or more, even if their weight doesn’t change. This improvement generally puts them at a lower risk of early death than people considered to be of normal weight but out of shape, Dr. Gaesser said.
On the other hand, if heavy people lose weight by dieting (not through illness), their statistical risk of dying young usually drops by about 16%, but not in all studies. Some research cited in the new review concluded that weight loss among obese people does not lower mortality risks.
The new review is not designed to determine precisely how exercise or weight loss affects longevity in people with obesity. But in many of the studies they looked at, Gaesser said, people who lost weight on a diet regained it, then tried again — a “yo-yo” approach to weight loss that often contributes to metabolic problems like diabetes, high cholesterol and shorter life expectancy.
On the other hand, exercise combats those same conditions, he said. It can also, unexpectedly, replenish people’s fat stores.
“People with obesity often lose some visceral fat when they exercise,” he said, even though the overall weight loss is negligible. Visceral fat, which accumulates deep within our bodies, increases the risks of type 2 diabetes, heart disease, and other conditions.
Some of the studies they cite have found that exercise also alters molecular signaling within other fat cells in ways that can improve insulin resistance, no matter what a person’s weight. “Exercise seems to make fat more fit,” said Gaesser.
The main takeaway from the new review, he concluded, is that you don’t have to lose weight to be healthy. “You will be better off, in terms of mortality risk, increasing your physical activity and fitness than intentionally losing weight,” he said.
Translated by Luiz Roberto M. Gonçalves
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