Many people believe that exercise controls weight by increasing your metabolism so you burn extra calories all day long. A review of the world’s literature from the University of South Australia in Adelaide shows that you have to be in very good shape to exercise vigorously enough to increase your metabolism. This means that most exercisers are not able to exercise hard enough to burn extra calories for a significant time after they finish exercising, so increased post-exercise metabolism does not cause most exercisers to lose weight.
Researchers monitor changes in metabolism by measuring how much oxygen your body uses over a period of time. The maximum amount of oxygen that you can use during exercise in a given time is called VO2max. To increase the amount of oxygen that your body uses after exercising, you must exercise at an intensity of at least 50 percent of your VO2max, which is too much for casual exercisers. You have to exercise very vigorously to increase your oxygen consumption and body temperature for more than a few minutes.
This study shows that if a person wants to increase his metabolism for from 3 to 24 hours, he must exercise for more than 50 minutes at 70 percent of his VO2max, or more than 6 minutes at 100 percent of his VO2max. You need to be very fit to be able to exercise at these levels. For most people, weight control depends on more on how long you exercise, and far less on the extra calories that you burn after you finish exercising.
Gabe Mirkin, M.D., has been a practicing physician for over 50 years. He is board-certified in sports medicine, allergy and immunology, pediatrics, and pediatric immunology. This article was originally published on DrMirkin.com. Subscribe to his free weekly Fitness & Health newsletter.
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