title: Perception of overweight and obesity among Portuguese adolescents: an overview of associated factors.
abstract: OBJECTIVE
  A national, representative school-based sample of Portuguese youth was used to both identify psychosocial indicators that distinguish obese and overweight adolescents from their peers, and key explainers of body image among obese and overweight adolescents.
  
  
  METHODS
  Data on 5697 sixth, eighth and tenth grade public school students, age 11-16 years, from Portugal who participated in the 1998 (HBSC/WHO) survey of adolescent health were analysed. Body mass index (BMI) was calculated based on self-reported weight and height. Body image was measured using a body image tool with a sequence of seven body silhouettes progressing from very thin to overweight. BMI was calculated by reported weight/height (kg/m2), and was categorized based on Cole normalization curve. Adolescents whose BMI was above the 95th percentile (obese) and those with a BMI between 85 and 95 (overweight) were compared with the remainder. Separate analyses of psychosocial variables were conducted by gender, using the chi2-test, t-tests, ANOVA and multiple linear regression.
  
  
  RESULTS
  There was a significant difference in physical activity between obese and non-obese youth (P<0.05). Girls reported dieting more than boys (P<0.001), with 15.3% of overweight teens dieting versus 6% of non-overweight teens. Those classified as overweight were significantly more likely to describe themselves as not healthy (P<0.001). A significantly greater proportion of obese/overweight versus non-overweight youth reported difficulty in making friends (P<0.001). BMI (beta=0.491; P=0.000), age (beta=-0.413; P=0.000), involvement in dieting (beta=0.110; P=0.000) and attitude toward appearance (beta=0.032; P=0.007) were significantly associated with body image.
  
  
  CONCLUSIONS
  Inaccurate perceptions of the need to diet, poorer self-perceived health status and potential social isolation of those who are overweight were found. The importance of these findings to health promotion strategies is discussed.
authors.affiliation: Adolescent Outpatient Clinic, Pediatric Division, Hospital de Santa Maria, Faculdade de Medicina de Lisboa, Lisboa, Portugal. helena.fonseca@netcabo.pt
authors.forename: Helena
authors.initials: H
authors.lastname: Fonseca
authors.forename: Margarida
authors.initials: M
authors.lastname: Gaspar de Matos
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001828:Body Image; D015992:Body Mass Index; D002648:Child; D003625:Data Collection; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D009765:Obesity / Q000523:psychology*; D011174:Portugal