NIH Research Festival
Weight loss interventions have stressed the need for increased physical activity to facilitate weight loss due to strong correlative links between obesity and exercise rates. However, energy expended during exercise can be rapidly compensated for by decreasing other aspects of energy expenditure, often diminishing the successfulness of exercise-based weight loss interventions. Here, we used running wheels, a popular translational model of physical activity, to explore energetic compensation in mice and to determine whether exercise can lead to significant and enduring changes in energy expenditure. Adult C57BL/6 mice were individually housed with ad libitum access to food and water and given access to a running wheel for 3 weeks; energy expenditure was measured using both an energy balance method (Ravussin et al., 2013) and indirect calorimetry. Whereas wheel running significantly increased over the 3 weeks (5000/day in week 1 vs. 20000/day in week 3; p < 0.01), average daily energy expenditure did not significantly change over the course of the experiment. We then explored potential mechanisms of energetic compensation and found that off-wheel physical activity significantly decreases following wheel use, suggesting that mice behaviorally compensate for exercise-associated changes in energy expenditure. These data demonstrate the inability of wheel running to cause a significant change in daily energy expenditure and, if translated to weight loss interventions in humans, allude to the inability of exercise alone to facilitate long-term weight loss.
Scientific Focus Area: Systems Biology
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