We’ve all heard the standard weight loss mantra: eat less and exercise more. However, some weight loss programs rely entirely on the first part, lowering caloric intake, without focusing at all on activity levels. New research by Elinor Sullivan and Judy Cameron shows why this doesn’t work.
The researchers gave monkeys a low calorie diet and monitored their activity levels. As the calories decreased, so did the activity level of the animals. In effect, the animals were compensating for the lack of food by using up less energy. After one month, there was no significant weight loss among the monkeys. An alternate group of monkeys were trained to run on a treadmill for an hour a day and that group of monkeys did lose weight.
This decrease in activity may be a natural coping mechanism for creatures that don’t always have access to ample food. If this data applies to humans (and there’s no reason to think it wouldn’t), it means dieting alone is unlikely to be sufficient for weight loss. The natural inclination to use less energy as food intake decreases must also be overcome.