Physically active communities have minimal obesity rates. This was true of all hunter-gatherer societies, subsistence farmers, and children who played outdoors.1 So how could a Time a magazine article from last year advises people Not exercise to lose weight?2
The author of the The article noted disappointing results for weight loss programs and wanted people to focus on the other great benefits of exercise in terms of health, longevity and happiness. Experiments that used exercise to promote weight loss typically provided subjects with about 30 minutes a day of moderate exercise such as brisk walking. These manipulations mostly failed to produce any lasting weight loss in overweight people.
Does this mean we should abandon exercise as a means of weight management? Hardly. After all, it’s clear that people who live in physically active communities aren’t overweight.3 The problem isn’t that physical activity doesn’t control body weight but that these subjects didn’t get it Enough exercise to adjust body weight to a healthier level. How much is enough? Among Indigenous people whose activity levels have been studied in careful research, none averaged less than 90 minutes a day of vigorous physical activity.3
Imagine an experiment where people were given one third of an aspirin to treat a headache. Researchers would incorrectly conclude that aspirin does not relieve pain.
In the minority of studies in which overweight subjects completed 90 minutes of exercise per day, positive results were achieved in terms of permanent weight loss. However, not all participants benefited. That’s because modern inactivity and nutrition patterns alter human physiology in ways that make it difficult to maintain a healthy body weight. Sugar in the diet plays a major role, as does insulin, the hormone that regulates blood sugar levels.
The history of insulin resistance
A high sugar diet causes obesity as established in animal experiments many decades ago where rodents had unlimited access to sugar laden drinking water. This principle was confirmed in a natural experiment on humans, finding that people who drink a lot of sugary sodas are at a higher risk of obesity. It is curious that, in fact, we will repeat animal experiments on our children and expect different results.
How does sugar in the diet cause obesity? When people consume sugary snacks or sweet drinks, their blood sugar rises and insulin is released which pulls the sugar out of the circulation and promotes fat synthesis and storage.
When the diet contains a lot of sugar, insulin levels are elevated most of the time. As a result, insulin receptors lose their sensitivity so blood sugar remains elevated. This condition is known as secondary diabetes and is associated with obesity and many related health problems including high blood pressure, kidney disease and liver disease.
Secondary diabetes is a tragic result of poor eating and exercise habits that are ingrained in modern life. It is a chronic condition and was widely considered incurable so that overweight teenagers could anticipate lifelong health challenges. Yet there is encouraging evidence that behavioral measures that increase physical activity and adopting an improved diet improve weight regulation and normalize blood sugar.
Getting back to nature
One of the more intriguing pieces of evidence involved urban Aboriginal people who were overweight and suffered from secondary diabetes. When they returned to their ancestral lifestyle of hunting and gathering, they lost weight and their blood sugar returned to normal levels.4 These beneficial results reflected greatly increased levels of physical activity and a diet that was more varied, contained more fiber and lacked refined sugar. Other promising evidence comes from weight loss experiments using high levels of exercise.
The problem with exercise for weight loss isn’t that it’s ineffective; rather, it is that the time commitment is perceived as unreasonable. Overweight people can also suffer injuries from sustained physical activity that discourage further exercise. This is unfortunate given the many health and longevity benefits of exercise. In fact, exercise time may more than pay off in increased longevity and a better quality of life in the future.
The benefits of physical activity do not require strenuous activities such as running and weight lifting, although these activities reduce the amount of time required. For many people, selecting low-intensity activities such as walking, gardening, or crafts such as woodworking and house painting is preferable. Prolonged bouts of inherently interesting hobbies are good for mobilizing fat and saving us from the dangers of spending too much time sitting. So, we Should exercise to lose weight and reap many other potential benefits, from better health and increased longevity to improved mood and social integration.
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