ABSTRACT
The Kiel Obesity Prevention Study (KOPS) has been performed since 1996. Examinations were performed at age 6, 10 and 14 years. In addition, birth weight as well as height and weight at age 2 years were collected retrospectively. For the study 4,997, 1,671 and 748 children were recruited at baseline (at age 6 years) as well as at 4 and 8-year follow-up, respectively. In this paper we will analyze and discuss (i) the important time period for preventive measures, (ii) effect sizes needed for successful interventions and (iii) suitable approaches for preventive measures. The main results were: (i) at age 6 years persistence of overweight was 69% while at younger ages persistence was 21% only. Thus, school entry was shown to be an important period for preventive measures. (ii) Interventions have to reduce energy balance by 140 kcal/day to prevent overweight (e.g. a reduction of energy intake). (iii) Prevention programs should involve the family and focus on increasing physical activity.
Subject(s)
Body Weight , Obesity/epidemiology , Students/statistics & numerical data , Adolescent , Age Distribution , Child , Female , Germany/epidemiology , Humans , Longitudinal Studies , Male , Prevalence , Risk FactorsABSTRACT
OBJECTIVES: The aim of this study was to assess the validity of self-reported height and weight and resulting body-mass-index (BMI) in adolescents, to identify influencing factors and to generate appropriate algorithms for the correction of self-reported values. METHODS: In the Kiel Obesity Prevention Study (KOPS) height and weight were assessed in 2,706 12- to 17-year-old adolescents by self-report and by measurements. Differences between self-reported and measured values were calculated. Algorithms for correction of self-reported data were generated in a random sample (n=941) and validated in another random sample (n=946). RESULTS: Overestimation of height and underestimation of weight resulted in a remarkable underestimation of BMI. Girls underestimated BMI more than boys (-0.8±1.0 kg/m² vs. -0.4±1.1 kg/m²; p<0.01), overweight adolescents underestimated more than normal weight adolescents (boys: -1.4±1.4 kg/m² vs. -0.3±0.9 kg/m²; p<0.01; girls:-1.6±1.3 kg/m² vs. -0.7±0.8 kg/m²; p<0.01). Prevalence of overweight and obesity was underestimated by 2.0% and 1.5%, respectively, in boys and by 2.2% and 2.0%, respectively in girls. Differences between self-reported and measured values were influenced by gender and weight status. Correction of self-reported data resulted in approaching the valid overweight prevalence. However, underestimations persisted. CONCLUSIONS: Self-reported height, weight and BMI calculated from these values are discrepant from measured data and cause underestimation of the prevalence of overweight and obesity in adolescents. Correction of self-reported values is possible. However, valid data can only be assessed by measurements of height and weight.
