As health and fitness professionals our goal is to help people become healthier, which encompasses more than weight loss. There is strong scientific evidence that greater levels of physical fitness promotes greater health benefits, for example decreasing the risk of diabetes, stroke, and heart disease. Swain & Franklin (2005) suggested in their review of both clinical trails and epidemiological studies that improving VO2max is more important for cardiovascular health benefits than merely engaging in moderate intensity physical activity. The researchers proposed that both the acute and chronic physiological adaptations to aerobic capacity (VO2) following vigorous exercise, such as lower resting heart rate, higher resting stroke volume, and lower resting blood pressure, promote greater cardiovascular disease protection than can be produced through moderate or low intensity physical activity.
A point here is the distinction between “exercise” and “physical activity.” Exercise is planned, structured repetitive movement designed to improve or maintain physical fitness, where physical activity is any energy requiring movement carried out by the musculoskeletal system. Swain & Franklin indicate that low to moderate physical activity may not be sufficient for improving aerobic capacity and providing cardiovascular benefits as a structured exercise program would be.
Although I agree that exercise alone is not the most effective way to lose weight, I also believe that a healthy body composition is more important than the number on the scale. Exercise focused on building lean muscle mass contributes to healthier body composition and metabolic processes as well as decreases 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), and even induce these favorable changes in body composition without an accompanying decline in weight. Irving et al. (2008) controlled for energy expenditure when examining the effects of low and high intensity exercise on total abdominal fat. The findings supported greater improvements in both fitness level and body composition with higher intensity aerobic exercise.
Slentz, et al. (2004) examined the effects of different exercise intensity on weight, body composition and waist circumference. After finding significantly greater improvements in all measurements in the groups that exercised at the lower volume of 12 miles per week at moderate (40% to 55% of peak V02) and vigorous intensities (65% to 80% of peak volume) when compared to the non-exercising control group, the researchers also found that the higher volume higher intensity group (20 miles per week at 65% to 80% of peak volume) lost more body mass than all the groups. Interestingly, the author also found that the non-exercising control group gained weight during the 8-month study. Both these studies indicate the benefits of exercise to promote health body composition and weight management.
Weight loss through diet alone does not promote lean muscle mass, does not increase insulin sensitivity, and does not reduce hypertension. The message is clear; exercise promotes greater health benefits than 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, 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 and determination. 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.
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