title: Lifestyle and obesity in adolescence and young adulthood: results from the Amsterdam Growth And Health Longitudinal Study (AGAHLS).
abstract: OBJECTIVE
  To investigate if there is a longitudinal relationship between the development of fat mass in males and females (aged between 12-28 y) and their lifestyle, with respect to diet and physical activity.
  
  
  METHODS
  In the Amsterdam Growth And Health Longitudinal Study (AGAHLS), a group of 500 boys and girls are being followed from the age of 13 y (mean age 13.5 y), over a period of 20 y until the age of 32 y (mean age 32.5 y).
  
  
  METHODS
  Data from AGAHLS are analysed of six repeated measurements of growth (body height, body mass, four skinfolds), health parameters with respect to cardiovascular disease (CVD) (obesity, hypertension, hypercholesterolaemia) and two important lifestyle tractors: physical activity (PA) (weighted energy output) and dietary intake (DI) (total energy intake, contribution of fat, carbohydrate and protein) of about 200 males and females between the ages of 13-27 y.
  
  
  RESULTS
  The longitudinal results of PA show a steep decrease in the energy expenditure from the age of 13 y from about 4500 Mets per week to 3000 Mets per week at the age of 27 y in both sexes. The longitudinal results of DI also show a decrease in energy intake per kilogram body mass from about 225 kJ per day at the age of 13 y to about 155 kJ at the age of 27 y. During adolescence, boys show a 15% higher energy intake and a 20% higher energy expenditure than girls. At the age of 27 y, the difference between the sexes in energy intake is reduced to 10% and the difference in energy expenditure disappears. Results of tracking analyses over the period of 15y indicate a low stability coefficient of PA (0.34; 0.19-0.49), but higher coefficients of DI (0.55; 0.45-0.64) and fat mass (0.63; 0.56-0.71). The search for important lifestyle factors that can discriminate high- from low-risk participants for a high fat mass, estimated from the sum of four skinfolds and body mass (BM), resulted in an Odds Ratio (OR) of 1.5 (1.2-1.8) with daily intake of proteins and an OR of 0.81 (0.69-0.96) with PA. Surprisingly the fat mass is negatively related with the daily intake of energy per kg BM (OR: 0.37; 0.28-0.49). The longitudinal relation between fat mass and PA (corrected for DI) between the ages of 13-27 y, showed a significant inverse relationship (P<0.01) if fat mass was estimated from the sum of four skinfolds, but not if estimated from the body mass index (BMI).
  
  
  CONCLUSIONS
  Over the adolescent and young adult period from 13-27 y, fat mass indicates a fairly good predictability. A high PA in both sexes is related with a low fat mass. Therefore promotion of habitual physical activity in the adolescent period seems effective in the early prevention of obesity.
authors.affiliation: Institute for Research in Extramural Medicine (EMGO Institute), Faculty of Medicine, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: H C
authors.initials: HC
authors.lastname: Kemper
authors.forename: G B
authors.initials: GB
authors.lastname: Post
authors.forename: J W
authors.initials: JW
authors.lastname: Twisk
authors.forename: W
authors.initials: W
authors.lastname: van Mechelen
mesh_terms: D000293:Adolescent; D000328:Adult; D015992:Body Mass Index; D002648:Child; D002149:Energy Intake; D005260:Female; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence