Body Weight and Exercise

Exercise burns calories. Yet, numerous expert panels evaluating the science behind exercise and weight loss have reached the same conclusion: exercise alone as a weight-loss method produces minimal results.¹

It takes a lot of exercise to burn a significant amount of calories. A person needs to exercise enough to burn about 5 ½ calories per pound of body weight per day in order to maintain his or her current body weight.² For an adult weighing 170 pounds, that means 925-950 calories, which is roughly equivalent to walking 9-10 miles, raking for 4 hours, vacuuming for 3 hours or practicing yoga for 3 ½ hours.

To go beyond maintaining and lose one pound of fat solely through exercise, a person needs to burn an additional 3,500 calories. That means that a 170-pound adult would need to walk another 5-10 miles (the equivalent of 500 to 1,000 calories) per day to lose 1-2 pounds per week. This amount of exercise everyday is not realistic for most people.

Overestimating Activity Level
Another limiting factor in exercise for weight loss is that people don't estimate their food and exercise levels accurately. Numerous research studies have found that it is common for individuals who are trying to lose weight to overestimate their physical activity.³ At the same time, it is common to underestimate calories consumed.⁴

Taken together, without careful attention to both food and exercise, it is very easy to "eat" the calories burned in exercise. For example, it takes about an hour on the treadmill for a man of 170 pounds to burn off a bagel (without butter or cream cheese), a few cookies, or a donut. Each 30-minute workout at a circuit training gym for women (e.g., Curves) burns about 150 calories for a 150 pound woman or the equivalent of a 12-ounce glass of orange juice.

Different Regimens, Same Results
There is no "right" exercise for weight loss. In a randomized, controlled, weight-loss trial of obese women that specifically compared a structured activity regimen (aerobic exercise classes) with a lifestyle activity regimen (focus on increasing time and effort spent in everyday chores), both types of activity led to comparable results after one year.⁵

While the actual contribution of exercise to weight loss is modest, it is helpful and additive to the weight loss achieved with diet. In fact, the few hundred calories that are burned with regular physical activity can make the difference between a diet that feels depriving and one that is sustainable.

This content is reviewed regularly. Last updated June 20, 2012.

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RELATED INFORMATION

Other Science Library Topics:

• Health Benefits of Exercise
• Exercise Intensity Levels
• Exercise and Preventing Weight (Re)Gain

FOOTNOTES

¹National Heart, Lung, and Blood Institute Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. Obes Res 1998;6 (Suppl 2):51S-209S.

²Saris WH. Fit, fat and fat free: the metabolic aspects of weight control. Int J Obes Relat Metab Disord S2: S15-21, 1998.

³Jakicic JM, Polley BA, Wing RR. Accuracy of self-reported exercise and the relationship with weight loss in overweight women. Med Sci Sports Exerc. 30(4):634-8, 1998.

⁴Lissner L. Measuring food intake in studies of obesity. Public Health Nutr. 5(6A):889-92, 2002.

⁵Andersen RE, Wadden TA, Bartlett SJ, Zemel B, Verde TJ, Franckowiak SC. Effects of lifestyle activity vs structured aerobic exercise in obese women: a randomized trial. JAMA. 27;281(4):335-40, 1999.