Overweight, Waist Circumference & Obesity in British
Youth
Waist Circumference Study Aim
A comparison of changes over time in waist circumference (a measure of
central fatness) and body mass index (a measure of overall obesity) in
British youth.
Waist Circumference Study Method
Representative cross sectional surveys in 1977, 1987, and 1997. Young
people aged 11-16 years surveyed in 1977 (boys) and 1987 (girls) for the
British Standards Institute and in 1997 (both sexes) for the national
diet and nutrition survey.
Waist Circumference Study Method
Waist circumference, expressed as a standard deviation score using the
first survey as reference, and body mass index (weight (kg)/height (m)2),
expressed as a standard deviation score against the British 1990 revised
reference. Overweight and obesity were defined as the measurement exceeding
the 91st and 98th percentile, respectively.
Waist Circumference Study Results
Waist circumference increased sharply over the period between surveys
(mean increases for boys and girls, 6.9 and 6.2 cm, or 0.84 and 1.02 SD
score units). In percentile terms, waist circumference increased more
in girls than in boys. Increases in body mass index were smaller and similar
by sex (means 1.5 and 1.6, or 0.47 and 0.53 SD score units). Waist circumference
in 1997 exceeded the 91st percentile in 28% (n=110) of boys and 38% of
girls (against 9% for both sexes in 1977-87), whereas 14% and 17%, respectively,
exceeded the 98th percentile (3% in 1977-87). The corresponding rates
for body mass index in 1997 were 21% of boys and 17% of girls exceeding
the 91st percentile (8% and 6% in 1977-87) and 10% and 8% exceeding the
98th percentile (3% and 2% in 1977-87).
Waist Circumference Study Conclusion
Trends in waist circumference during the past 10-20 years have greatly
exceeded those in body mass index, particularly in girls, showing that
body mass index is a poor proxy for central fatness. Body mass index has
therefore systematically underestimated the prevalence of obesity in young
people.
Source: London Metropolitan University
2003
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