Relationship between Regular Leisure-Time Physical Activity and Underweight and Overweight Status in Taiwanese Young Adults: A Cross-Sectional Study

The aim of this study was to determine the association between regular leisure-time physical activity (LTPA) and various body mass index (BMI) categories in Taiwanese young adults. A total of 10,802 young adults (18–44 years) were enrolled in a national telephone survey. The questionnaire data from this survey included socio-demographic characteristics, zip code of residence, LTPA behaviors, self-reported health status, and self-evaluated anthropometric measurements, which included height, body weight, and BMI. Regular and non-regular LTPA behaviors were defined as follows: (1) Regular LTPA: participants who reported breathing quickly and sweating when participating in 150–300 min per week of moderate-intensity LTPA or 75–150 min per week of vigorous-intensity LTPA. (2) Non-regular LTPA: the rest of the participants. The various BMI categories were defined as (1) underweight (BMI < 18.5 kg/m 2 ), (2) normal weight (18.5 ≤ BMI < 24 kg/m 2 ), (3) overweight (24 ≤ BMI < 27 kg/m 2 ), and (4) obese (BMI ≥ 27 kg/m 2 ). When compared with participants with non-regular LTPA, participants with regular LTPA exhibited lower risks of being overweight (odds ratio [OR], 0.837; 95% confidence interval [CI] 0.738–0.948) and underweight (OR, 0.732; 95% CI 0.611–0.876). However, there was no significant relationship between regular LTPA and obesity risk when using non-regular LTPA as the baseline after adjusting for potential confounders. The study results revealed that regular LTPA effectively reduced the risks of being underweight and overweight. However, for people with obesity, regular LTPA was unable to significantly decrease their obesity risk.