Body mass index in 7-9-y-old French children: frequency of obesity, overweight and thinness.
To assess the frequency of different grades of nutritional status (obesity, overweight and thinness) in French children aged 7-9 y using four current definitions based on body mass index (BMI). Data were collected in 2000 in a randomly selected sample of French children following the protocol recommended by the European Childhood Obesity Group (ECOG). After computing the BMI (weight/height squared), four references were used to define grades of nutritional status: (1) the French references to define thinness and overweight (3rd and 97th percentiles respectively); (2) the Must et al references to define thinness, overweight and obesity (5th, 85th and 95th percentiles respectively); (3) the International Obesity Task Force cut-offs to define overweight and obesity; and (4) the Center for Disease Control 2000 references to define thinness, overweight and obesity (5th, 85th and 95th percentiles respectively). Age and gender standardized frequencies were estimated in 1582 children. According to the French, Must et al, IOTF and CDC references, overweight (including obesity) affected 16.3, 23.9, 18.1 and 20.6% of children, respectively; obesity affected 9.3, 3.8 and 6.4% of children according to the Must, IOTF and CDC references, respectively. Thinness was present in 3.9, 6.0 and 6.0% of children according to the French, Must and CDC references. Whatever the definition, little difference was observed between sexes. Through age classes, as a rule, overweight and obesity tended to decrease while thinness tended to increase. The present study revealed an increasing prevalence of overweight in comparison with previous French data and a trend for increasing prevalence of thinness. The IOTF-based prevalence of overweight (including obesity) in 2000 in France was similar with the prevalence recorded in the late 1980s in the USA and the prevalence of obesity in 2000 in France was similar to the prevalence of obesity in the late 1970s in the USA. Data in France are comparable to those reported in other studies conducted in Western Europe. This study provides baseline information for analysis of time trends and for geographical comparisons.