Obesity is a serious public health concern. More than half of British adults are overweight, and obesity among preschool children has increased by an alarming 70% in the past generation.1 2 We aimed to explore parents' awareness of overweight and obesity in themselves and their children, and their degree of concern about weight. Participants, methods, and resultsWe studied 277 healthy randomly recruited children (mean age 7.4 years) and parents from the EarlyBird study.3 Overweight and obesity were defined as body mass index at least 25 and 30 in adults, and at least 91st and 98th centiles of the UK 1990 body mass index reference curves for children. 4 Before we weighed them, parents completed a written questionnaire asking them to estimate their own and their child's weight on a five point scale ranging from "very underweight" to "very overweight." Responses indicating level of concern about weight were similarly ranked from "very worried about underweight" to "very worried about overweight."Children and parents were significantly heavier than UK norms (table): 52/277 (19%) children, 141/273 (52%) mothers, and 165/230 (72%) fathers were overweight (including obese). Among overweight parents, 40% mothers (45% fathers) judged their own weight "about right" and 27% (61%) were unconcerned about their weight.Only a quarter of parents recognised overweight in their child. Even when obese, 33% mothers (57% fathers) saw their child's weight as "about right." Parents were less likely to identify overweight in sons than daughters: only 27% of overweight or obese boys were classified as at least "a little overweight," compared with 54% of overweight girls (P = 0.01). More mothers than fathers correctly assessed their child's weight (84% v 76%, P = 0.06).Maternal weight status did not affect mothers' awareness of their chidren's weight: 82% of overweight mothers were correct compared with 82% of normal weight mothers (P = 0.50). However, only 74% overweight fathers were correct compared with 85% normal weight fathers (P = 0.08).More than half of the parents of obese children expressed some degree of concern about their child's weight, but only a quarter were even "a little worried" if their child was overweight. Most parents (86%) who were unaware that their child was overweight, were also unconcerned about their child's weight. One in ten parents expressed some concern about underweight in normal weight children.Prevalence of overweight in parents in the highest and lowest socioeconomic groups did not differ-59% in classes I and II were overweight compared with 62% in classes VI, VII, and VIII (P = 0.63; National Statistics Socioeconomic Classification 2001). Neither was there a difference in correct perception of the child's weight between socioeconomic groups (78% v 82%, P = 0.34).

Most excess weight before puberty is gained before 5 years of age. Weight at 5 years of age bears little relation to birth weight but closely predicts weight at 9 years of age. Single measures of current weight are predictive of metabolic health, whereas weight gain within a specific period adds little. A single measure of weight at 5 years of age provides a pointer to future health for the individual. If metabolic status at 9 years of age means future risk, diabetes/cardiovascular prevention strategies might better focus on preschool-aged children, because the die seems to be largely cast by 5 years of age, and a healthy weight early in childhood may be maintained at least into puberty.

Objective To establish in children whether inactivity is the cause of fatness or fatness the cause of inactivity. Design A non-intervention prospective cohort study examining children annually from 7 to 10 years. Baseline versus change to follow-up associations were used to examine the direction of causality. Setting Plymouth, England. Participants 202 children (53% boys, 25% overweight/ obese) recruited from 40 Plymouth primary schools as part of the EarlyBird study. Main outcome measures Physical activity (PA) was measured using Actigraph accelerometers. The children wore the accelerometers for 7 consecutive days at each annual time point. Two components of PA were analysed: the total volume of PA and the time spent at moderate and vigorous intensities. Body fat per cent (BF%) was measured annually by dual energy x ray absorptiometry. Results BF% was predictive of changes in PA over the following 3 years, but PA levels were not predictive of subsequent changes in BF% over the same follow-up period. Accordingly, a 10% higher BF% at age 7 years predicted a relative decrease in daily moderate and vigorous intensities of 4 min from age 7 to 10 years (r=−0.17, p=0.02), yet more PA at 7 years did not predict a relative decrease in BF% between 7 and 10 years (r=−0.01, p=0.8).Conclusions Physical inactivity appears to be the result of fatness rather than its cause. This reverse causality may explain why attempts to tackle childhood obesity by promoting PA have been largely unsuccessful.

In children, physical activity above the government-recommended intensity of 3 METs is associated with a progressive improvement in metabolic health but not with a change in BMI or fatness. Girls habitually undertake less physical activity than boys, questioning whether girls in particular should be encouraged to do more, or the recommendations adjusted for girls.

OBJECTIVEInsulin resistance (IR) is associated with diabetes. IR is higher during puberty in both sexes, with some studies showing the increase to be independent of changes in adiposity. Few longitudinal studies have reported on children, and it remains unclear when the rise in IR that is often attributed to puberty really begins. We sought to establish from longitudinal data its relationship to pubertal onset, and interactions with age, sex, adiposity, and IGF-1.RESEARCH DESIGN AND METHODSThe EarlyBird Diabetes study is a longitudinal prospective cohort study of healthy children aged 5–14 years. Homeostasis model assessment (HOMA-IR), skinfolds (SSF), adiposity (percent fat, measured by dual-energy X-ray absorptiometry), serum leptin, and IGF-1 were measured annually in 235 children (134 boys). Pubertal onset was adduced from Tanner stage (TS) and from the age at which luteinizing hormone (LH) first became serially detectable (≥0.2 international units/L).RESULTSIR rose progressively from age 7 years, 3–4 years before TS2 was reached or LH became detectable. Rising adiposity and IGF-1 together explained 34% of the variance in IR in boys and 35% in girls (both P < 0.001) over the 3 years preceding pubertal onset. The contribution of IGF-1 to IR was greater in boys, despite their comparatively lower IGF-1 levels.CONCLUSIONSIR starts to rise in mid-childhood, some years before puberty. Its emergence relates more to the age of the child than to pubertal onset. More than 60% of the variation in IR prior to puberty was unexplained. The demography of childhood diabetes is changing, and prepubertal IR may be important.