Interventions aiming to reduce social inequalities of weight status in adolescents usually focus on lifestyle behaviours, but their effectiveness is limited. This study analysed the effect of achieving levels of dietary intake (DI) and/or physical activity (PA) guidelines on reducing social inequalities in weight status among adolescents. We included adolescents from the PRomotion de l’ALIMentation et de l’Activité Physique – INÉgalité de Santé (PRALIMAP-INÈS) trial with weight status data available at baseline and 1-year follow-up (n 1130). PA and DI were measured using the International Physical Activity Questionnaire and a validated FFQ, respectively. We estimated the likelihood of a 1-year reduction in BMI z-score (BMIz) and population risk difference (PRD) under hypothetical DI and PA levels and socio-economic status using the parametric G-formula. When advantaged and less advantaged adolescents maintained their baseline DI and PA, we found social inequalities in weight status, with a PRD of a 1-year reduction in BMIz of −1·6 % (–3·0 %, −0·5 %). These inequalities were not observed when less advantaged adolescents increased their proportion of achieving DI guidelines by 30 % (PRD = 2·2 % (–0·5 %, 5·0 %)) unlike the same increase in PA (PRD = −3·9 % (–6·8 %, −1·3 %)). Finally, social inequalities of weight status were not observed when levels of achievement of both PA and DI guidelines increased by 30 % (PRD = 2·2 % (–0·5 %, 4·0 %)). Enhancing DI rather than PA could be effective in reducing social inequalities in weight status among adolescents. Future interventions aiming to reduce these inequalities should mostly target DI to be effective.

Rapid prenatal and postnatal weight gain seem to alter appetite regulation and hypothalamic functions through different pathways; however, little is known on how early life growth trajectories may influence appetitive traits in school-age. We aimed to explore the associations between weight trajectories from birth to 5 years and appetitive traits at 7. Participants were from the Generation XXI birth cohort (n 3855). Four weight trajectories were investigated: ‘normal weight gain’ (closely overlaps the 50th percentile in the weight-for-age curve), ‘weight gain during infancy’ (low birth weight and weight gain mainly during infancy), ‘weight gain during childhood’ (continuous weight gain since birth) and ‘persistent weight gain’ (always showing higher weight than the average). Appetitive traits were assessed through the Children’s Eating Behaviour Questionnaire. Associations were tested using generalised linear models, adjusted for maternal and child characteristics. Compared with ‘normal weight gain’, those in the other growth trajectories showed greater enjoyment of food and eating in response to food stimuli (i.e. Food Responsiveness) but were less able to compensate for prior food intake and ate faster at 7 (i.e. less Satiety Responsiveness and Slowness in Eating). Also, those with ‘weight gain during infancy’ showed to have greater Emotional Overeating and less Emotional Undereating and were fussier. Associations were stronger if greater weight gain occurred during infancy. Early infancy seems to be a sensitive period in the development of later appetitive traits. The control of rapid growth during infancy, besides strategies focused on the overall environment where children are living, is necessary.

Assessing children’s growth adequately is important due to the necessary prevention of adequate body composition, especially at pre-pubertal age. Simpler measurements such as anthropometry or bioimpedance, using equations validated in Caucasian children, have been demonstrated to overestimate or underestimate fat mass percentage (FM%) or fat-free mass (FFM) in Chilean children. In a sample of 424 children (198 boys and 226 girls) of 7–9 years old, the three component (3C) model was assessed, where total body water was determined by 2H dilution and body volume by air displacement plethysmography, in order to design and validate anthropometry and bioimpedance equations. The FM (%) equation specific for Chilean children was validated as (1·743 × BMI z-score) + (0·727 × triceps skinfold) + (0·385 × biceps skinfold) + 15·985, against the 3C model (R2 0·79). The new FFM equation (kg) generated was (log FFM = (0·018 × age) + (0·047 × sex) + (0·006 × weight) + (0·027 × resistance) + 2·071), with an R2 0·93 (female = 1 and male = 2). The Bland–Altman analysis shows a mean difference of 0·27 (sd 3·5) for the FM% in the whole group as well as 0·004 (sd 0·9) kg is the mean difference for the bioelectrical impedance analysis (BIA) FFM (kg) equation. The new equations for FM (%) and FFM (kg) in Chilean children will provide a simple and valid tool for the assessment of body composition in cohort studies or to assess the impact of nutritional programmes or public policies.

Complementary feeding (CF) and overweight relationships during early childhood are inconsistent in the literature. We described the association of CF during the first year of life with risk of overweight at 24 months of age in the population-based 2004 and 2015 Pelotas (Brazil) Birth Cohorts (2004c and 2015c). CF introduction was evaluated at the 3 and 12 months’ follow-ups by asking mothers using a list of foods. Risk of overweight at 24 months of age was BMI-for-age z-score above +1sd from the median of the WHO 2006 growth standards. Our analyses included 3823 (2004c) and 3689 (2015c) children. Early introduction CF (before 6 months of age) prevalence in 2004c was 93·3 (95 % CI 92·5, 94·1) % and in 2015c was 87·2 (95 % CI 86·1, 88·2) %. Tea was the item introduced earlier in both 2004c (68·8 %) and 2015c (55·7 %). At 6 months of age, vegetable mash was the most introduced food in 2004c (33·5 %) and 2015c (47·9 %). Between 2004c and 2015c, the introduction of fresh milk decreased 82·1 to 60·5 % and yogurt from 94·4 to 78·1 % during the first year. Risk of overweight prevalence at 24 months was 33·0 (95 % CI 31·6, 34·5) % in 2004c and 32·0 (95 % CI 30·5, 33·5) % in 2015c. In 2015c, the adjusted odds of risk of overweight at 24 months were increased 1·66 and 1·50 times with the early introduction of fresh/powdered milk: plus water, tea or juice, and plus semi-solid/solid food groups, respectively. It is essential to reinforce the adherence to global recommendations on timely feeding introduction and encourage exclusive breast-feeding until 6 months of age to prevent child overweight.

BMI, waist circumference (WC) and waist-to-height ratio (WHtR) can be used for discriminating children and adolescents at risk of CVD. However, consensus on how to use these anthropometric indicators is lacking for children and adolescents in Asia. Discrete criteria are promoted internationally, but continuous variables could be used. Data from a survey of 10 949 Vietnamese school-aged children (6–18 years) were used to evaluate the performance of anthropometric indicators to identify elevated blood pressure (BP), dyslipidaemia or at least three cardiovascular risk factors (CVRF). Weight, height, WC and BP were measured using standardised protocols; 1009 participants who had blood lipids were analysed. AUC was used to assess the performance, and the Youden index to identify optimal cut-offs. The prevalence of elevated BP, dyslipidaemia and CVRF was 26·5, 49·3 and 12·2 %, respectively. BMI, WC and WHtR had low capacity to identify elevated BP and dyslipidaemia (AUC range 0·61–0·66) but moderate capacity to identify CVRF (0·72–0·74). Optimal BMIZ cut-offs to identify elevated BP, dyslipidaemia and CVRF were 0·40, 1·01 and 1·1 sd; for WC z-score, they were 0·06, 0·49 and 0·62 sd; for WHtR, optimal cut-offs were close to 0·5. A BMIZ cut-off of 1·0 sd and a WHtR cut-off of 0·5 would, therefore, be useful criteria to identify Vietnamese children who are likely to have CVRF. However, further validation of these criteria in other studies of Asian children and adolescents is needed.

Faster eating rates are associated with increased energy intake, but little is known about the relationship between children’s eating rate, food intake and adiposity. We examined whether children who eat faster consume more energy and whether this is associated with higher weight status and adiposity. We hypothesised that eating rate mediates the relationship between child weight and ad libitum energy intake. Children (n 386) from the Growing Up in Singapore Towards Healthy Outcomes cohort participated in a video-recorded ad libitum lunch at 4·5 years to measure acute energy intake. Videos were coded for three eating-behaviours (bites, chews and swallows) to derive a measure of eating rate (g/min). BMI and anthropometric indices of adiposity were measured. A subset of children underwent MRI scanning (n 153) to measure abdominal subcutaneous and visceral adiposity. Children above/below the median eating rate were categorised as slower and faster eaters, and compared across body composition measures. There was a strong positive relationship between eating rate and energy intake (r 0·61, P<0·001) and a positive linear relationship between eating rate and children’s BMI status. Faster eaters consumed 75 % more energy content than slower eating children (Δ548 kJ (Δ131 kcal); 95 % CI 107·6, 154·4, P<0·001), and had higher whole-body (P<0·05) and subcutaneous abdominal adiposity (Δ118·3 cc; 95 % CI 24·0, 212·7, P=0·014). Mediation analysis showed that eating rate mediates the link between child weight and energy intake during a meal (b 13·59; 95 % CI 7·48, 21·83). Children who ate faster had higher energy intake, and this was associated with increased BMI z-score and adiposity.