Underweight, overweight, and obesity in childhood and adolescence are associated with adverse health consequences throughout the life-course. Our aim was to estimate worldwide trends in mean body-mass index (BMI) and a comprehensive set of BMI categories that cover underweight to obesity in children and adolescents, and to compare trends with those of adults. We pooled 2416 population-based studies with measurements of height and weight on 128·9 million participants aged 5 years and older, including 31·5 million aged 5-19 years. We used a Bayesian hierarchical model to estimate trends from 1975 to 2016 in 200 countries for mean BMI and for prevalence of BMI in the following categories for children and adolescents aged 5-19 years: more than 2 SD below the median of the WHO growth reference for children and adolescents (referred to as moderate and severe underweight hereafter), 2 SD to more than 1 SD below the median (mild underweight), 1 SD below the median to 1 SD above the median (healthy weight), more than 1 SD to 2 SD above the median (overweight but not obese), and more than 2 SD above the median (obesity). Regional change in age-standardised mean BMI in girls from 1975 to 2016 ranged from virtually no change (-0·01 kg/m2 per decade; 95% credible interval -0·42 to 0·39, posterior probability [PP] of the observed decrease being a true decrease=0·5098) in eastern Europe to an increase of 1·00 kg/m2 per decade (0·69-1·35, PP>0·9999) in central Latin America and an increase of 0·95 kg/m2 per decade (0·64-1·25, PP>0·9999) in Polynesia and Micronesia. The range for boys was from a non-significant increase of 0·09 kg/m2 per decade (-0·33 to 0·49, PP=0·6926) in eastern Europe to an increase of 0·77 kg/m2 per decade (0·50-1·06, PP>0·9999) in Polynesia and Micronesia. Trends in mean BMI have recently flattened in northwestern Europe and the high-income English-speaking and Asia-Pacific regions for both sexes, southwestern Europe for boys, and central and Andean Latin America for girls. By contrast, the rise in BMI has accelerated in east and south Asia for both sexes, and southeast Asia for boys. Global age-standardised prevalence of obesity increased from 0·7% (0·4-1·2) in 1975 to 5·6% (4·8-6·5) in 2016 in girls, and from 0·9% (0·5-1·3) in 1975 to 7·8% (6·7-9·1) in 2016 in boys; the prevalence of moderate and severe underweight decreased from 9·2% (6·0-12·9) in 1975 to 8·4% (6·8-10·1) in 2016 in girls and from 14·8% (10·4-19·5) in 1975 to 12·4% (10·3-14·5) in 2016 in boys. Prevalence of moderate and severe underweight was highest in India, at 22·7% (16·7-29·6) among girls and 30·7% (23·5-38·0) among boys. Prevalence of obesity was more than 30% in girls in Nauru, the Cook Islands, and Palau; and boys in the Cook Islands, Nauru, Palau, Niue, and American Samoa in 2016. Prevalence of obesity was about 20% or more in several countries in Polynesia and Micronesia, the Middle East and north Africa, the Caribbean, and the USA. In 2016, 75 (44-117) million girls and 117 (70-178) million boys worldwide were moderately or severely underweight. In the same year, 50 (24-89) million girls and 74 (39-125) million boys worldwide were obese. The rising trends in children's and adolescents' BMI have plateaued in many high-income countries, albeit at high levels, but have accelerated in parts of Asia, with trends no longer correlated with those of adults. Wellcome Trust, AstraZeneca Young Health Programme.

BACKGROUND AND OBJECTIVES: The effects of lifestyle interventions on cardio-metabolic outcomes in overweight children have not been reviewed systematically. The objective of the study was to examine the impact of lifestyle interventions incorporating a dietary component on both weight change and cardio-metabolic risks in overweight/obese children. METHODS: English-language articles from 1975 to 2010, available from 7 databases, were used as data sources. Two independent reviewers assessed articles against the following eligibility criteria: randomized controlled trial, participants overweight/obese and ≤18 years, comparing lifestyle interventions to no treatment/wait-list control, usual care, or written education materials. Study quality was critically appraised by 2 reviewers using established criteria; Review Manager 5.1 was used for meta-analyses. RESULTS: Of 38 eligible studies, 33 had complete data for meta-analysis on weight change; 15 reported serum lipids, fasting insulin, or blood pressure. Lifestyle interventions produced significant weight loss compared with no-treatment control conditions: BMI (−1.25kg/m², 95% confidence interval [CI] −2.18 to −0.32) and BMI z score (−0.10, 95% CI −0.18 to −0.02). Studies comparing lifestyle interventions to usual care also resulted in significant immediate (−1.30kg/m², 95% CI −1.58 to −1.03) and posttreatment effects (−0.92 kg/m², 95% CI −1.31 to −0.54) on BMI up to 1 year from baseline. Lifestyle interventions led to significant improvements in low-density lipoprotein cholesterol (−0.30 mmol/L, 95% CI −0.45 to −0.15), triglycerides (−0.15 mmol/L, 95% CI −0.24 to −0.07), fasting insulin (−55.1 pmol/L, 95% CI −71.2 to −39.1) and blood pressure up to 1 year from baseline. No differences were found for high-density lipoprotein cholesterol. CONCLUSIONS: Lifestyle interventions can lead to improvements in weight and cardio-metabolic outcomes. Further research is needed to determine the optimal length, intensity, and long-term effectiveness of lifestyle interventions.

Importance Diet and exercise represent the mainstays of obesity treatment. No systematic review has been conducted comparing the effect of dietary and exercise intervention in reducing metabolic risks in overweight children. Objective To compare the effects of diet-only intervention with those of diet plus exercise or exercise only on weight loss and metabolic risk reduction in overweight children. Evidence Review English-language articles from 1975 to 2010 available from 7 databases were reviewed. One person searched the databases. Two independent reviewers assessed abstracts and articles against the following eligibility criteria: randomized controlled trials conducted in overweight and obese children aged 18 years or younger, comparing dietary intervention with a diet plus exercise program or an exercise-only program. Study quality was critically appraised by 2 reviewers using established criteria. The main outcome measures were body mass index, body fat percentage, lean body mass, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, fasting glucose, and fasting insulin. Findings Fifteen studies were identified and included. Based on the small number of short-term trials currently available, both diet-only and diet plus exercise interventions resulted in weight loss and metabolic profile improvement. However, the addition of exercise to dietary intervention led to greater improvements in levels of high-density lipoprotein cholesterol (3.86 mg/dL [to convert to millimoles per liter, multiply by 0.0259]; 95% CI, 2.70 to 4.63), fasting glucose (−2.16 mg/dL [to convert to millimoles per liter, multiply by 0.0555]; 95% CI, −3.78 to −0.72), and fasting insulin (−2.75 μIU/mL [to convert to picomoles per liter, multiply by 6.945]; 95% CI, −4.50 to −1.00) over 6 months. The diet-only intervention caused greater reductions in levels of triglycerides (at the end of active intervention) and low-density lipoprotein cholesterol (at subsequent follow-up). Conclusions and Relevance This review provides insights into the impact of dietary and exercise interventions on metabolic risk reduction in the pediatric population. However, further studies are required to confirm the evidence with rigorous design, appropriate sample size, longer duration of follow-up, and better strategies to improve compliance and achieve long-term sustainability.

Purpose.: To examine how perceptions of the local neighborhood relate to adolescents' walking and cycling. Design.: Exploratory cross-sectional study. Setting.: Birth cohort from the Nepean Hospital, Sydney, Australia. Subjects.: Three hundred forty-seven adolescents (79.1% response rate; 49.6% boys; mean age = 13.0 ± 0.2 years) and their parents. Measures.: Self-report and parental-report questionnaires. Results.: Multiple linear regressions, adjusted for level of maternal education, revealed that boys who reported having many peers to hang out with locally, cycled for recreation (β = 0.242, p = .006) or for transport (β = 0.141, p = .046) more often, and walked for transport for longer (β = 0.129, p = .024) on weekdays. For girls this variable was related to cycling for recreation on weekends (β = 0.164, p = .006) and walking to school (β = 0.118, p = .002). Adolescents who waved/talked to neighbors walked for transport more often (boys, β = 0.149, p = .037; girls, β = 0.119, p = .012). Girls who perceived local roads to be safe spent more time walking for transport on weekdays (β = 0.183, p = .007) and for exercise on weekends (β = 0.184, p = .034). Parents' perception of heavy traffic was negatively associated with boys' walking for transport (β = −0.138, p = .037) and many aspects of girls' walking and cycling. Conclusion.: Social interaction and road safety may be important predictors of adolescents' walking and cycling in their neighborhood. Limitations are the use of self-report and cross-sectional data. Longitudinal studies may clarify these relations.

Metformin therapy for adults and children with type 2 diabetes is well established. However, its role in the treatment of insulin resistance and obesity in children and adolescents is less clearly defined. We assessed the effect of metformin on body composition and insulin sensitivity in pediatric subjects with exogenous obesity. Patients referred to a pediatric endocrine clinic were enrolled in a randomized, double-blind, crossover trial. Twenty-eight patients (13 males) aged 9-18 yr participated in the study. Patients received metformin (1 g twice daily) and placebo for 6 months, each with a 2-wk washout period. Body composition (anthropometry, dual-energy x-ray absorptiometry, and abdominal magnetic resonance imaging), and insulin sensitivity (Si; minimal model, fasting insulin and glucose) were measured at baseline and 6 and 12 months. Mean age of subjects at baseline was 12.5 +/- 2.2 yr, median body mass index z-score 2.54 (range, 1.93-2.85). Metformin had a greater treatment effect over placebo for weight (-4.35 kg, P = 0.02), body mass index (-1.26 kg/m(2), P = 0.002), waist circumference (-2.8 cm, P = 0.003), sc abdominal adipose tissue (-52.5 cm(2), P = 0.002), and fasting insulin (-2.2 mU/liter, P = 0.011). Si improved in 45% of subjects while on metformin and 27% of subjects while on placebo (P = 0.21). Metformin therapy for obese insulin-resistant pediatric patients results in significant improvement in body composition and fasting insulin. Although improvement in Si was noted in many individuals, Si was a less useful parameter for analysis of group data, possibly because of effects of variable compliance and changing Si during puberty.