Exercise Trumps Calories continued...
In a new study that hasn't been published, Cameron's team put overweight, inactive monkeys on a strict diet. They didn't lose much weight.
"I don't think most people who try to diet will be surprised," Cameron says. "The body immediately tries to compensate for calories you are not taking in by dropping your metabolic rate and lowering your activity level. There was no way to get around the fact that activity matters a great deal. Altogether, our feeling is that activity is very, very important in controlling body weight."
Can Obese Humans Become Active?
A lot of studies show that obese people aren't as active as lean people are. Cameron's study now suggests that it isn't obesity that turns people into couch potatoes -- it's inactivity that makes people obese.
However, it may not be a simple thing for overweight or obese people to become more active. Cameron says it's possible to predict how active monkeys will be when they're only 1 week old.
"Why are some monkeys more active? You would think it was what situation they were living in," Cameron says. "But we looked at monkeys with acres to run around in and many playmates. You would expect them to be very active. And if you move them indoors with fewer playmates, they should not be as active. But that was not true. A sedentary monkey was just as sedentary, and an active monkey was just as active no matter the setting. And we find this remains true over time."
It remains to be seen whether human couch potatoes can switch to an active lifestyle. But Cameron's work may have put one myth to rest: It's not your metabolism.
People who gain or don't gain weight often point to their inherent metabolic rate as the culprit. For monkeys, at least, this isn't so. Monkeys' metabolic rates didn't vary much. And those with the highest metabolic rate were no more likely to gain or lose weight than those with the lowest metabolic rate.