title: Associations between Physical Activity and Obesity Defined by Waist-To-Height Ratio and Body Mass Index in the Korean Population.
abstract: OBJECTIVE
  This study investigated the associations between physical activity and the prevalence of obesity determined by waist-to-height ratio (WHtR) and body mass index (BMI).
  
  
  METHODS
  This is the first study to our knowledge on physical activity and obesity using a nationally representative sample of South Korean population from The Korea National Health and Nutrition Examination Survey. We categorized individuals into either non-obese or obese defined by WHtR and BMI. Levels of moderate-to-vigorous physical activity were classified as 'Inactive', 'Active', and 'Very active' groups based on the World Health Organization physical activity guidelines. Multivariable logistic regression was used to examine the associations between physical activity and the prevalence of obesity.
  
  
  RESULTS
  Physical activity was significantly associated with a lower prevalence of obesity using both WHtR and BMI. Compared to inactive men, odds ratios (ORs) (95% confidence intervals [CIs]) for obesity by WHtR ≥0.50 were 0.69 (0.53-0.89) in active men and 0.76 (0.63-0.91) in very active men (p for trend = 0.007). The ORs (95% CIs) for obesity by BMI ≥25 kg/m2 were 0.78 (0.59-1.03) in active men and 0.82 (0.67-0.99) in very active men (p for trend = 0.060). The ORs (95% CIs) for obesity by BMI ≥30 kg/m2 were 0.40 (0.15-0.98) in active men and 0.90 (0.52-1.56) in very active men (p for trend = 0.978). Compared to inactive women, the ORs (95% CIs) for obesity by WHtR ≥0.50 were 0.94 (0.75-1.18) in active women and 0.84 (0.71-0.998) in very active women (p for trend = 0.046). However, no significant associations were found between physical activity and obesity by BMI in women.
  
  
  CONCLUSIONS
  We found more significant associations between physical activity and obesity defined by WHtR than BMI. However, intervention studies are warranted to investigate and compare causal associations between physical activity and different obesity measures in various populations.
authors.affiliation: Department of Physical Education, College of Education, Seoul National University, Seoul, South Korea.
authors.forename: On
authors.initials: O
authors.lastname: Lee
authors.affiliation: Department of Kinesiology, College of Human Sciences, Iowa State University, Ames, Iowa, United States of America.
authors.forename: Duck-Chul
authors.initials: DC
authors.lastname: Lee
authors.affiliation: Department of Counseling, Health, and Kinesiology, College of Education and Human Development, Texas A&M University-San Antonio, San Antonio, Texas, United States of America.
authors.forename: Sukho
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Physical Education, College of Education, Seoul National University, Seoul, South Korea.
authors.forename: Yeon Soo
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology*; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D065927:Waist-Height Ratio