A monkey research project out of the Oregon National Primate Research Center found active monkeys stayed lean, while couch-potato monkeys got fat - no matter how much they ate. This study is another testament to sway dieters to exercise as they try to lose weight.

Over a nine-month period, the researchers measured the monkeys' activity level. They kept them on a high-fat diet and tracked the animals' weight, food intake, and metabolic rate. Some chimps ate a lot. Some did not. Food intake did not make any difference in the monkeys' weight.

Some chimps were very active. Some weren't. This, however, did make a huge difference in how much the monkeys weighed. The active monkeys did not gain weight over time, but the sedentary monkeys did gain weight, even if they were not eating a lot of food. Researchers found the biggest predictor of weight gain was how active the monkeys were, which overrode how much food they were eating.

This study helps to explain why people who try to lose weight by dieting alone rarely succeed. Before someone makes a monkey out of you – get active to control your body weight. Judging by the monkey study, physical activity should be the number one priority for those looking to lose weight.