Height, weight, and the assessment of obesity in children.

There has been recent concern about the observed alteration over the past few decades of the distribution of weight for height in both adults and children and, in particular, about the increasing proportion of 'heavy' children (Scott, 1961; Khosla and Lowe, 1968). Increasing amounts of overweight are known to be associated with increasing morbidity and mortality rates for adults of a given age and sex (Kannel, LeBauer, Dawber, and McNamara, 1967) and several studies have shown that excessive weight in childhood is likely to persist (Mullins, 1958; Lloyd, Wolff, and Whelan 1961; Asher, 1966; Eid, 1970). Moreover, it has recently been found that overweight children may experience more illness than other children at a very early age (HutchinsonSmith, 1970; Tracey, De, and Harper, 1971). Extreme overweight will usually indicate some degree of obesity, but it is evident that measures of height and weight alone cannot provide an accurate measure of adiposity as they will also reflect the size of the other body compartments. Several indices derived from height and weight have been shown to correlate highly with measures of adiposity, such as skinfold thickness, body density, and fat content calculated by subtraction of lean body mass from total body weight, lean body mass being derived from potassium-40 measurements (Billewicz, Kemsley, and Thomson, 1962; Forbes, 1964; Khosla and Lowe, 1968; Evans and Prior, 1969). The correlation coefficients are of the order 0-8 but may be lower for some values of height, which led Florey (1970) to suggest that height and weight alone do not give an adequate estimate of adiposity. Despite their limitations, however, the ease and relative accuracy with which measurements of height and weight can be taken make them useful measures for epidemiological studies and screening programmes. From an examination of weight distributions and measures of adiposity it is usually assumed that in adults the distribution of obesity is independent of