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Why exercise to combat obesity, not diet

A recent exercise and weight study revealed that young rats prone to obesity (there really is a strain that are like this) are much less likely to become obese if they run during adolescence than if they don't run.Not that this is stunning.

But, here's the interesting part, they also were metabolically healthier, and had different stomach microbes, than rats that keep the weight off by cutting back on food (and not running).

Sort of a diet alone vs. exercise test.

In essence, the runners, while weighing the same as the dieters at the end of the study, seemed better set up to avoid weight gain in the future.

In this new study, which was published in Medicine & Science in Sports & Exercise, researchers at the University of Missouri in Columbia and other schools first gathered rats from a strain that has an inborn tendency to become obese, starting in adolescence. (Adolescence is also when many young people begin to add weight.)

These rats were young enough, though, that they were not yet overweight.

After weighing them, the researchers divided the animals into three groups:

  • Group one:allowed to eat as much kibble as they wished and to remain sedentary in their cages. These were the controls.
  • Group two: the exercise group, also was able to eat at will, but these animals were provided with running wheels in their cages. Rats like to run, and the animals willingly hopped on the wheels, exercising every day.
  • Group three: the dieting group, was put on a calorie-restricted meal plan. Their daily kibble helpings were about 20 per cent smaller than the amount that the runners ate, a portion size designed to keep them at about the same weight as the runners, so that extreme differences in body size would not affect the final results.

After 11 weeks, all of the animals were moved to specialized cages that could measure their metabolisms and how much they moved around. They then returned to their assigned cages for several more weeks, by which time they were effectively middle-aged.

At that point that group results were:

  • Group 1 (eaters):The control animals were obese, their physiques heavy with fat.
  • Group 2 (runners) and 3 (dieters) similarities:
  • The runners and the lower-calorie groups, had gained ounces but had put on far less weight than group one.
  • b.None were obese.
  • c.Both running and diet, had effectively protected the animals against their tendency to obesity.
  • Group 2 and 3 differences:
  • But beneath the skin, the runners and the dieters looked very unalike.
  • By almost all measures, the runners were metabolically healthier, with better insulin sensitivity and lower levels of bad cholesterol than the dieters.
  • They also burned more fat each day for fuel, according to their metabolic readings, and had more cellular markers related to metabolic activity within their brown fat than the dieting group. Brown fat, unlike the white variety, can be quite metabolically active, helping the body to burn additional calories.
  • Interestingly, the runners also had developed different stomach microbes than the dieters, even though they ate the same food. The runners had greater percentages of some bacteria and smaller populations of others than the dieters or the control group; these particular proportions of gut bugs have been associated in a few previous studies with long-term leanness in both animals and people.
  • Perhaps most striking, "the runners showed no signs of compensatory eating or compensatory inactivity," said Victoria Vieira-Potter, an assistant professor of nutrition and exercise physiology at the University of Missouri who oversaw the study. They didn't eat more food than the control group, despite running several miles every day and, according to the specialized cages, actually moved around more when not exercising than either of the other groups of rats.

In essence, the runners, while weighing the same as the dieters at the end of the study, seemed better set up to avoid weight gain in the future.