Dropping calories is one of the surest methods used by those who want to cut weight, but until now, the common belief has been that less energy consumed will lead to poorer workout performance. Not so, says a recent scientific report.
In order to understand the effects of calorie restriction on physical performance, a new study tracked mice to see if fewer calories would lead to less wheel running. The results will surprise many, who feel that missing a few macros is an excuse to skip a gym session. At odds with that notion, the data showed that cutting calories by 20% did not significantly reduce the distance that mice voluntarily chose to run each day. “Voluntary exercise was remarkably resistant to reducing the amount of food by 20% and even by 40%,” commented University of California, Riverside biologist and corresponding study author Theodore Garland, Jr. “They just kept running.”
How was the study carried out?
Researchers spent three weeks recording a baseline level of running activity for the mice, then a further week with calories reduced by 20%, and a final week at minus 40%. This experiment was completed both with regular mice and “high runner” mice that are bred to enjoy running, in order to reflect populations with different base activity levels.
What were the results?
The 20% reduction had no significant effect on performance, and although the high runners reduced their total distance slightly with 40% calorie restriction, even then the distance was just an 11% reduction. One of the reasons that experts think mice, and people, can continue to exercise on fewer calories is due to the ‘runners high’ effect brought about by increased levels of dopamine and cannaboid levels in the brain thanks to getting our sweat on.
Wheel running for mice, or simply running or working out for the rest of us is a “self-rewarding behavior,” explained Garland, Jr. And, those who worry that cutting calories by 20% while still engaging in intense activity might lead to severe weight loss, this may be another myth. Researchers were surprised to find that 20% fewer calories had a negligible effect on mass, and a lesser than expected weight drop even at 40%.
Still, if there is less energy consumed, how can this be? “There has to be some type of compensation going on if your food goes down by 40% and your weight doesn’t go down very much,” says Garland. “Maybe that’s reducing other types of activities, or becoming metabolically more efficient, which we didn’t yet measure.”
While there is further work to be done to fully understand these results, the fact remains that missing out on your regular meal intake doesn’t necessarily need to spell the end of a gym day. “We don’t want people on diets to say, ‘I don’t have enough energy, so I’ll make up for it by not exercising,’” says Garland. “That would be counterproductive, and now we know, it doesn’t have to be this way.”
