A Response to the Time Magazine Article “Why Exercise Won’t Make You Thin”

Written by Karen Moreno

The American College of Sports Medicine (ACSM) sent a request to members and professionals to get the “right health message out to the public.” This request was made in response to the Time magazine article “Why Exercise Won’t Make You Thin,” which too narrowly examined the role of exercise and weight loss. For the most part the article is a personal account of the author’s dissatisfaction with a long-term exercise program and lack of results. An Exercise Physiologist and ACSM member was consulted for the story. Unfortunately, according to the researcher, his study outcomes and opinions were selectively reported in the article. There are five points the ACSM is concerned will confound the public health message regarding the benefits of exercise and physical activity:
§       “Losing weight matters more than being aerobically fit in the prevention of heart disease”
§       “One can’t lose weight from exercise because exercise makes you hungrier – and willpower can’t conquer the hunger enough to make good food choices”
§       “Exercising 60 to 90 minutes most days of the week in order to lose weight (a recommendation from a ACSM Position Stand) is unrealistic”
§       “Leisure-time physical activity-just moving around more during the day – is more effective for weight loss than dedicated exercise”
§       “Vigorous exercise depletes energy resources so much that it leads to overeating – i.e., weight gain”
My concern is that this article will undermine a person’s commitment to exercise and a healthy lifestyle. A distinction needs to be made between exercise and physical activity. Exercise is physical activity, however physical activity is not exercise. Exercise is planned, structured repetitive movement designed to improve or maintain physical fitness, where physical activity is any movement carried out by the musculoskeletal system that requires energy. In other words, moving across the room is considered physical activity. There is strong scientific evidence that exercise and physical fitness promote greater health benefits than physical activity. Swain & Franklin (2005) found in their review of both clinical trails and epidemiological studies that the acute and chronic physiological adaptations to aerobic fitness following vigorous endurance exercise promote greater cardiovascular disease protection than moderate or low intensity physical activity.
exercise-heartAlthough I agree that exercise alone is not the most effective way to lose weight, I also believe that healthy body composition is more important than the number on the scale. Exercise focused on building lean body mass contributes to healthier body composition and metabolic processes, as well as diminishes age related declines in strength and power. Vigorous aerobic exercise has also been found to reduce visceral and subcutaneous abdominal fat (the fat distribution associated with diabetes and heart disease). Irving, et al. (2008) examined the effects of low and high intensity exercise on total abdominal fat while controlling for energy expenditure. The results indicate greater improvements in both physical fitness and body composition with the group exercising at higher intensity when energy expenditure was comparable to the group exercising at the lower intensity. This means the higher intensity group exercised for less amount of time however expended the same amount of energy as the lower intensity group, suggesting that how hard we exercise maybe more important for reducing abdominal fat than workout duration or energy expended. It was interesting to note that these favorable body composition changes were induced without a reduction in body weight.
Slentz, et al. (2004) examined the effects of three different exercise intensities and volumes (measured as distance ran) on weight, body composition and waist circumference. The researchers found two interesting outcomes: 1) significantly greater improvements in all three of the above mentioned measurements in the groups that ran the shorter distance at moderate or vigorous intensities when compared to the non-exercising control group, and 2) the group that ran the greater distance at higher intensity lost more over all body mass than all the groups. Incidentally, Slentz et al. also found that the non-exercising control group gained weight during the 8-month study. The researchers concluded that not only was exercise intensity beneficial for promoting weight loss, improving body composition and reducing waist circumference; exercise in general was effective for weight management.
Weight loss through diet alone does not promote lean muscle mass, stimulate metabolic processes, increase insulin sensitivity, or improve cardiorespiratory fitness. The message is clear; exercise promotes greater health benefits diet alone, even if the scale does not budge. After reading the Time magazine article, the additional comments I would like to make are as follows: 1) if your exercise routine is not enjoyable or providing the expected results, change it and examine whether or not your expectation are realistic and your training program is appropriate; and 2) just because you exercise does not mean you can eat everything and anything you desire. The commitment to a healthy lifestyle requires knowledge, effort, determination and accountability. If your goal is to lose weight and your exercise routine is only using 300 Calories of energy, don’t eat a 500 Calorie post workout meal.
Karen Moreno, MA Candidacy Kinesiology/Exercise Physiology
BA Social Science/Education
ACSM Addressed Myths About Weight Loss, Exercise http://epid.blogspot.com/2009/08/acsm-addresses-myths-about-weight-loss.html
Irving, B.A., Davis, C.K., Brock, D.W., Weltman, J.Y., Swift, D., Barrett, E. J.,
Gaesser, G.A., and Weltman, A. (2008). Effect of exercise training intensity on abdominal visceral fat and body composition. Medicine & Science in Sports & Exercise, 40(11),1863-1872.
Slentz, C.A., Duscha, B.D, Johnson, J.L., Ketchum, K., Aiken, L.B., Samsa, G.P.,
Houmard, J.A., bales, C.W., and Kraus, W.E. (2004). Effects of the amount of exercise on body weight, body composition, and measures of central obesity. Archives of Internal Medicine, 164(1), 31-39.
Swain, D.P., and Franklin, B.A. (2005). Comparison of cardioprotective benefits
of vigorous versus moderate intensity aerobic exercise. The American
Journal of Cardiology, 97, 141-147.