In this study, obese and prediabetic men and women who exercised while dieting lost less insulin sensitivity than those who dieted alone, even though all showed similar weight loss. was found to improve by a factor of two.
“These results demonstrate that regular exercise during a dietary weight loss program has even greater metabolic benefits compared to diet alone,” the study authors wrote. ing.
Researchers involved in the study said they hoped the findings would increase motivation among dieters, including those taking popular new weight-loss drugs such as Ozempic.
Samuel Klein, director of the Department of Geriatrics and Nutritional Sciences at the University of Washington School of Medicine in St. Louis and the study’s lead author, said that whether you’re on drugs or not, “exercise should definitely be on your agenda. should,” he said. .
Although the experiment was small, involving only 16 males and females, the results are scientifically proven that physical activity while reducing calories causes changes in the body that diet alone cannot compete with. strengthened the consensus.
Can Exercise Help You Lose Weight?
Klein said, “It’s natural to wonder” whether it’s necessary to bother exercising while losing weight. After all, the relationship between exercise and weight is notoriously unstable. “If you want to lose weight, people tell you to be physically active,” says Klein. But in most cases, “physical activity doesn’t affect weight much.”
In fact, exercising alone without dieting at the same time rarely leads to significant weight loss. many studies show, and in some cases can lead to weight gain. In general, exercise burns fewer calories than expected. A 30-minute walk burns around 150 calories, which can easily be replaced with a cookie or sports drink. Exercise often increases appetite.
Overall, it’s “easier to cut calories” for most people than to start exercising to lose weight, says Klein.
But this study provides new evidence for the benefits of exercising when trying to lose weight, even if it doesn’t promote or increase weight loss.
The Nature Metabolism study used data from several existing experiments on weight loss. In one experiment, eight sedentary men and women with obesity and prediabetes were put on a low-fat, “plant-first” diet under supervision. All meals were served individually, and each slowly lost her 10 percent of her body weight.
A second group of eight obese and prediabetic men and women were fed the same diet, but also started exercising six times a week. Four of these sessions were supervised and included approximately one hour of moderate-intensity aerobic exercise, including brisk walking on a treadmill, twice per week. Resistance training once a week. And interval training once a week. For the remaining two days, participants trained independently at home.
The researchers adjusted the exercisers’ diets to maintain weight loss similar to that of other groups, but they needed very few calories, Klein said.
The program continued until each person lost 10% of their weight, and it took most people about 5 months to lose 10% of their weight. Before and after, researchers took blood, biopsied muscles, and took fecal samples to check people’s insulin sensitivity, fitness, and other health conditions.
Helping Weight Losers Get Twice As Healthy
Ultimately, the men and women in the diet-only group were leaner and had improved cholesterol profiles and other markers of improved metabolic health. Perhaps most importantly, their insulin sensitivity was significantly improved.
“We expected them to be healthier, and they were,” Klein said.
But scientists were surprised by the exercise participants.
The improvement in insulin sensitivity in that group was twice that of the dieting group. They also showed a higher number of new blood vessels and mitochondria within the muscle. Mitochondria are the tiny organelles that power our cells, and generally the more mitochondria, the better.
Those who exercised also increased their strength by about 13 percent and their endurance by 10 percent. Those on a diet, on the other hand, were about 2 percent weaker and 6 percent weaker than they were at the start of the study.
“We were wondering how much extra benefit the exercise would add,” Klein said. “We were amazed at the strength of its potency.”
However, there are caveats to this study. John Tifoldt, professor and director of the University of Kansas Diabetes Institute, said the study relied on “a very small sample size.” And all these volunteers had obesity and prediabetes. It is not clear whether results in healthier people are similar.
The researchers also closely monitored everyone’s diet and exercise, and adherence to the program was “very high,” Klein said. However, few people will receive such guidance during weight loss, and the range and intensity of training may intimidate some.
“At this point, we don’t know if reducing the amount of exercise will help,” says Klein.
He and his colleagues hope to explore some of these issues in future studies. However, based on the evidence already available, dieting but not exercising “doesn’t provide sufficient metabolic health benefits, and our research suggests that those effects may be serious,” he concluded.
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