Exercise overcomes energy saving mechanisms during dieting in sheep

What is it about?

Reducing calories is a common means to lose weight, however it is difficult to maintain in the long term due to the way the body adapts. The body reduces how much energy it uses to ultimately preserve body weight (as if in a starvation-like situation); part of this is a reduction in heat generation termed thermogenesis. In this study, we demonstrated this very phenomena whereby reduced food intake in sheep decreased thermogenesis. They produced less heat. But in sheep that had regular exercise in addition to the diet, this energy-saving mechanism was partially overcome so that heat production. This means that despite those sheep eating less and exercising more, they were not reducing their thermogenesis to conserve body weight like those that only underwent dieting. The potentially means that this combination of diet and exercise has a greater capacity to reduce body weight than initially thought. Indeed, over the four week period, this was the only intervention to reduce body fat. While adaptations were discovered in the brain, these did not explain the results, hence further investigation is required to fully understand the mechanisms driving this effect of exercise and diet together on thermogenesis.

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Why is it important?

This study provides further evidence to include exercise along with calorie restriction when attempting to reduce body fat and potentially treat obesity. This ability for exercise to counteract the effects of diet means that adding exercise to any weight loss diet regimen could not only increase the amount of energy expended through the act of exercising itself, but could increase metabolic rate outside of exercise. These changes are yet to be observed in humans, and this would be the next step.

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