English summary: CHANGES IN THE PREVALENCE OF OBESITY AMONG ADOLESCENTS - A STUDY OF THE NORTHERN FINLAND BIRTH COHORTS BORN IN 1966 AND 1986

Background

The prevalence of obesity is increasing among Finnish adolescents in general. Little research has been done on secular trends in body mass index and obesity among northern Finnish adolescents.

Methods

Data on self-reported and measured weight and height were prospectively collected at different time points in the northern Finland birth cohorts born in 1966 (N=12231) and 1986 (N=9479). Adolescents were classified as normal weight, overweight or obese, using age- and sex-specific IOTF cut-off points. Prevalence ratios were used to compare overweight and obesity between the cohorts.

Results

The prevalence of obesity among adolescents increased markedly during the twenty years. In 1980, 1% of 14-year-olds and in 2001-2002 3-4% of 16-year-olds were obese. Also the proportion of overweight adolescents doubled from 5-7% to 10-12%. Of 31-year-old young adults 8-9% were obese in 1997. Obesity seems to be quite permanent from adolescence to adulthood. A substantial proportion of normal weight adolescents become overweight young adults, which is a particularly worrying trend.

Conclusions

Increasing the resources in obesity prevention and care among children and youth should be prioritized. Nutritional aspects should be emphasized in the basic education of schoolteachers and health care staff. In addition to increasing the skills and knowledge at the individual level, it is also important to change the environment to support healthy lifestyle choices.