Obesity and underweight trends in Hong Kong primary school children

Abstract

Obesity and underweight trends in Hong Kong primary school children Ho SY1, Ruan RL1, Fong DYT2, Lee KY3, Chung WH3, Lam TH1 1 School of Public Health, The University of Hong Kong 2 School of Nursing, The University of Hong Kong 3 The Student Health Service, The Department of Health, Government of Hong Kong SAR The Student Health Service in Hong Kong measures the weight status of primary school students annually . We analysed these cross-sectional datasets on obesity and underweight trends from 1995/96 to 2008/09. An average of 334325 students per school year were analysed. Obesity and underweight were defined using body mass index cutoffs of 25 and 18.5 kg/m2, respectively, at age 18. Overall, sex, age and parental education specific prevalence estimates were calculated after weighting by sex and/or age. Obesity increased from 1995/96 to 2008/09 (16.1%-23.3%, 44.7% increase) overall, and greater increases were observed in boys (19.0% to 28.2%, 48.4% increase) than girls (13.0% to 18.0%, 38.5% increase), in younger age groups (<8 years 55.4%; 8-9 years 43.5%; ≥10 years 41.5%), and those with less educated parents (primary education or below 59.1%; secondary 53.1%; tertiary 30.4%). Underweight decreased from 17.6% to 11.4% (35.2% decrease) overall, and greater decreases were observed in boys (15.3% to 9.6%, 37.3% decrease) than girls (20.1% to 13.4%, 33.3% decrease), in the youngest age group (<8 years 36.8%; 8-9 years 33.9%; ≥10 years 35.5%), and those with less educated parents (primary education or below 37.1%; secondary 33.9%; tertiary 26.9%). In sum, the prevalence of obesity increased and underweight decreased in Hong Kong primary school children from 1995/96 to 2008/09. Greater increases in obesity were observed in boys, younger age groups and those with less educated parents.