“Wow — almost 2 h!” This was the response from my first-grade daughter as she finished adding up the number of minutes she had jogged to “burn off” the calories in a popular child meal combo from a large fast food chain. She was putting the final touches on her science project, which involved eating the meal, looking up the nutrition facts online, and completing multiple bouts of running (across several days) while wearing an activity tracking device. In line with my daughter’s reaction, I suspect that the average American has a highly skewed notion about the amount of activity required to negate all the calories he or she consumes. And the gross overestimation of the capacity of exercise to burn the extra calories we collectively consume is likely one of the culprits of the obesity epidemic we face today.
The consequences of allowing the myth to be perpetuated have at least two major consequences for youth with obesity: 1) we set up a false expectation for these children and their families, who after exercising and failing to lose weight, may experience disappointment and decide to abandon exercise altogether; and 2) we create a potentially subversive and counterproductive scenario in which nonadherence to appropriate dietary modification might be rationalized by an individual who assumes that any extra calories consumed can be canceled out easily and quickly by exercising just a little more. Therefore, the benefits and limitations of exercise need to be accurately portrayed and placed into an appropriate context whenever physical activity counseling is offered to individuals with obesity. Exercise can aid in weight loss, just not nearly as much as most people think.
In the current issue of the Journal, “Exercise for Obese Youth: Refocusing Attention from Weight Loss to Health Gains,” Shaibi et al. (3) expertly detail how exercise produces multiple beneficial health outcomes that are, unfortunately, too often deemphasized in favor of weight-based end points in many clinical trials. Indeed, exercise training can improve insulin resistance, beta-cell function, glucose tolerance, dyslipidemia, and vascular function, to name only a handful of benefits (3). One additional aspect of exercise and physical activity not fully appreciated is the role they play in weight loss maintenance. As described by investigators of the National Weight Control Registry study, physical activity appears to be indispensable in relation to preventing weight regain among adults (1,2). However, less is known about the role of physical activity on weight loss maintenance in children. Perhaps similar studies can be undertaken in children to improve our understanding regarding physical activity and weight loss maintenance and underscore their importance in the treatment schema.
At some point, hopefully not far on the horizon, effective and sustainable nonsurgical treatments will be available for children and adolescents afflicted with obesity. And when that day arrives, exercise will continue to be an important part of the equation, particularly as the focus begins to shift toward maintaining a healthy body weight and addressing risk factors for other chronic diseases. In the interim, we as a research and health care community should continue to tout all of the health benefits of exercise, yet challenge the commonly held assumption about its role in weight loss (i.e., a little activity can go a long way toward burning off those extra calories). In so doing, we might cause some parents to think twice about pulling up to the fast food window so frequently and free up some time for their first grader who may be interested in doing things other than jogging for 2 h · d-1.
Aaron S. Kelly
Departments of Pediatrics and Medicine
University of Minnesota Medical School
Dr. Kelly serves on a pediatric obesity advisory board for Takeda Pharmaceuticals but does not accept personal or professional income for his services.
1. Catenacci VA, Ogden LG, Stuht J, et al. Physical activity patterns in the National Weight Control Registry. Obesity (Silver Spring)
. 2008; 16 (1): 153–61.
2. Klem ML, Wing RR, McGuire MT, Seagle HM, Hill JO. A descriptive study of individuals successful at long-term maintenance of substantial weight loss. Am. J. Clin. Nutr.
1997; 66 (2): 239–46.
3. Shaibi GQ, Ryder JR, Kim JY, Barraza E. Exercise for obese youth: refocusing attention from weight loss to health gains. Exerc. Sport Sci. Rev.
2015; 43 (1): 41–47.