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

There hasbeenrecent concern about theobserved alteration overthepastfewdecades ofthedistribution ofweight forheight inbothadults and children and,inparticular, abouttheincreasing proportion of'heavy' children (Scott, 1961; Khosla andLowe,1968). Increasing amounts ofoverweight areknowntobeassociated withincreasing morbidity andmortality rates for adults ofagiven ageandsex (Kannel, LeBauer, Dawber, andMcNamara, 1967) andseveral studies haveshownthat excessive weight inchildhood islikely topersist (Mullins, 1958; Lloyd, Wolff, andWhelan1961; Asher, 1966; Eid, 1970). Moreover, ithasrecently beenfoundthat overweight children mayexperience moreillness thanother children ataveryearly age(HutchinsonSmith, 1970; Tracey, De,andHarper, 1971). Extremeoverweight willusually indicate some degree ofobesity, butitisevident that measures of height andweight alone cannot provide anaccurate measure ofadiposity asthey will also reflect thesize oftheother bodycompartments. Several indices derived fromheight andweight havebeenshownto correlate highly withmeasures ofadiposity, suchas skinfold thickness, bodydensity, andfatcontent calculated bysubtraction ofleanbodymassfrom total bodyweight, leanbodymassbeing derived from potassium-40 measurements (Billewicz, Kemsley, andThomson, 1962; Forbes, 1964; Khosla andLowe,1968; EvansandPrior, 1969). The correlation coefficients areoftheorder 0-8butmay belower forsomevalues ofheight, which ledFlorey (1970) tosuggest that height andweight alone donot give anadequate estimate ofadiposity. Despite their limitations, however, theeaseandrelative accuracy withwhichmeasurements ofheight andweight can betaken makethemuseful measures forepidemiological studies andscreening programmes. Fromanexamination ofweight distributions and measures ofadiposity itisusually assumed thatin adults thedistribution ofobesity isindependent of