Body fat percentage in adolescents is a better predictor of exercise effect on adiposity changes: a 4-year follow-up study.

Background: Exercise is generally recognized as beneficial to prevent obesity; however, it is not clear which indicator can better reflect the benefits, especially in adolescents. The aim of this study was to describe the effects of exercise on body mass and fat indexes and to clarify the significance of different indexes in clinical use.

Methods: We conducted a prospective cohort study involving 1,941 freshmen from 2014, followed-up biennially until 2018. Various body mass and fat indexes, including weight, height, waist and hip circumference and body fat percentage (BFP), were measured. Physical activity and other variables were collected by questionnaire. All study participants were divided into two groups according to the frequency and intensity of exercise.

Results: Compared with the low frequency and intensity exercise group, the high frequency and intensity exercise group had a lower increase in BFP during the 4-year follow-up, and no significant differences were observed in the changes of other indexes between the groups. Even after adjusting, the high frequency and intensity exercise group still exhibited a higher likelihood of reducing BFP.

Conclusions: High frequency and intensity exercise provides benefits for reducing BFP. No other body mass or fat indexes showed any association. BFP could be a much more sensitive indicator to detect and control obesity in adolescents.