Researchers obtained data for height, weight, and waist circumference, collected from surveys of young people over the past 10-20 years in Britain. They selected data on 4,560 young people aged 11-16 years for analysis.
Measures of waist circumference increased sharply over the period between surveys, particularly in girls. In 1997, 28% of boys and 38% of girls were defined as overweight by (against 9% for both sexes in 1977-87) and 14% of boys and 17% of girls were defined as obese (3% in 1977-87).
Increases in body mass index were smaller and similar in both sexes. In 1997, 21% of boys and 17% of girls were defined as overweight (against 8% and 6% in 1977-87) and 10% of boys and 8% of girls were defined as obese (3% and 2% in 1977-87).
These findings suggest that the accumulation of central body fat has risen more steeply than whole body fatness based on weight and height, say the authors. Body mass index has therefore systematically underestimated the prevalence of obesity in young people.
Increases in waist circumference on current and future illness in young people should be a cause for concern, they conclude.