15 mice were housed in indirect calorimetry chambers that contained running wheels. The experiment included a habituation phase, then a locked wheel phase, and finally a run as much as they wanted phase.
All told, despite a doubling of wheel use, the mice' total daily energy expenditures stayed roughly the same - elevated somewhat from their wheel locked baseline, but stuck at an elevation seen with slight use.
The researchers' not-meant-for-mice conclusion echoes my confirmation bias,
"physical activity should be encouraged for its overall health benefits, while expectations concerning its role in weight loss should be kept realistic."Exercise is primarily for health, not weight loss.