What is best for body fat reduction in obese adolescents – lifting, running or….both ?
Evidence shows that obesity levels among adolescents aged 10-16 years is increasing. Obesity-related chronic diseases, such as type 2 diabetes and cardiovascular disease can be controlled, but not reversed, with the use of expensive medications. Therefore, if unchecked, when an adolescent develops obesity at a young age, they may be an economic and social burden on the public health system for the rest of their life. Lifestyle modification programs, such as increasing physical activity levels remain the most cost-effective approach to treating obesity. However, it is unclear which exercise modality, such as aerobic training (AT), strength training (ST) or combined training (AT-ST) is optimal for obese adolescents. The aim of this exercise study was to determine the effects of AT, ST, and combined AT-ST on body fat loss in obese adolescents
How they did it?
This was a randomised clinical trial conducted at community-based exercise facilities in Canada. A total of 304 previously inactive obese (BMI of >30kg/m2) adolescents aged 14-18 years participated in a 22-week intervention and were randomly divided into four groups: (1) AT (n=75), (2) ST (n=78), (3) AT-ST (n=75) & (4) non-exercising control (n=76). All participants received dietary counselling, with a daily energy deficit of 250 kcal. The main study outcome was the percentage body fat loss measured by magnetic resonance imaging (MRI) and waist circumference. Each was assessed at baseline and 6 months.
What they found?
When compared to control, the AT, ST and AT-ST groups had decreases in body fat percentage (-0.3% vs. range -1.1-1.6%). However, there was no statistically significant difference between exercise groups. Similar findings were observed in waist circumference changes, with control at 6 months having changed -0.2cm, AT -3.0cm, ST -2.2cm and AT-ST -4.1cm. Again, there were no significant differences between exercise groups. In a sub-analysis, the researchers examined the role of exercise adherence in body fat reduction. Importantly, among those who attended >70% of sessions, body fat percentage loss was significantly greater in AT-ST (-2.4%) when compared to AT (-1.2%) and ST (1.6%).
Ok, what does this mean to me?
This large-scale exercise intervention showed that irrespective of the mode, 22-weeks of exercise was beneficial for body fat reduction among obese adolescents. Among those who attended the majority of exercise sessions, combined AT-ST training appeared the most favourable for body fat reduction.
Note: this study only used body fat reduction as the primary outcome. It is likely that exercise participation had other health benefits which were not assessed, such as improvements in aerobic fitness, muscle strength and mental health.
Title: Effects of aerobic training, resistance training, or both on percentage body fat and cardiometabolic risk markers in obese adolescents
Authors: Sigal RJ, Alberga AS, Goldfield GS, et al
Journal: JAMA Pediatrics