Objectives: To assess the average daily levels of physical activity, energy expenditure and the time and energy spent at different activities in two cohorts of Swedish adolescents. Design: Total energy expenditure (TEE) and physical activity level (PAL TEE/basal metabolic rate (BMR)) were estimated in 374 randomly selected healthy adolescents living in two different regions of Sweden on the basis of a seven-day activity diary (AD) and predicted BMR. A validation of the estimates from the AD with the doubly labelled water (DLW) method in a randomly selected subsample of 50 of these subjects is presented elsewhere. Setting: The Unit of Paediatric Physiology of the Department of Clinical Physiology, University Hospital, Uppsala and the Department of Paediatrics, Northern A È lvsborg Hospital, Trollha Èttan, Sweden. Results: No signi®cant differences in TEE and PAL were found between the adolescents of the two regions. High levels of TEE (14.2 and 10.9 MJ/d in boys and girls, respectively) and PAL (1.95 and 1.80) were observed. There was a close association between the PAL of the adolescents and their reported time spent sitting. Those with the lowest PAL values spent 3±6 h longer each day sitting compared to those with the highest PAL values. The results also indicate that everyday activities such as walking and bicycling have a crucial impact on the PAL values. Conclusions: In the 15 y old adolescents of the two studied regions of Sweden, high and concordant levels of energy expenditure and physical activity were found. Sponsorship: Swedish Medical Research Council (project no. 10379), Uppsala University, and the County Councils of Uppsala and Trollha Èttan. Descriptors: activity diary; basal metabolic rate; doubly labelled water method; energy expenditure; physical activity level; adolescents

Aim: This study investigated orlistat treatment in obese prepubertal children with regard to tolerance, safety and psychological well‐being. Methods: 11 healthy, severely obese prepubertal children (age 8.3–12.3 y, body mass index standard deviation score 5.3–9.2) were recruited for a 12wk open treatment. Before, during and after treatment, the participants were investigated by psychological evaluation, blood chemistry, and parameters reflecting obesity and fat mass. Results: The participants were able to comply with the treatment, as indicated by pill counts and self reports, and expressed a desire to continue the treatment after the study period. Gastrointestinal side effects were mild and tolerable. No negative effects on psychological or physical well‐being were detected, and the psychological evaluation demonstrated increased avoidance of fattening food, body shape preoccupation and oral control (p= 0.011). The median weight loss was 4.0 kg (range –12.7 to +2.5 kg, p= 0.016) and was highly correlated to decreased fat mass (regression coefficient 0.953, p < 0.01). Conclusion: This pilot study indicates that obese prepubertal children were able to reduce their fat intake to avoid gastrointestinal side effects. Thus, orlistat may be suitable as a component in behaviour‐modification programmes for obese children, and the results prompt a placebo‐controlled investigation of its effectiveness in promoting weight loss.

Bone mineral area (BA), total bone mineral content (TBMC) and total bone mineral density (TBMD) were assessed by dual-energy X-ray absorptiometry (DXA) in 396 randomly selected, healthy 15-year-old Swedish boys and girls. The influence of body size, pubertal development, physical activity level (PAL), total energy expenditure (TEE), dietary intake of energy, calcium and vitamin D, and alcohol and smoking habits on TBMC and TBMD were examined in bi- and multivariate analyses. In bivariate analyses BA, TBMC and TBMD showed strong correlations with weight, height and TEE in both sexes. In boys but not in girls these bone variables were significantly correlated with dietary intakes of energy, calcium and vitamin D. No significant correlations were found between PAL and the three bone variables. In multivariate analyses with TBMC as dependent variable BA, height, weight and Tanner stages explained 88% and 87% of the variance in boys and girls respectively. In similar analyses with TBMD as dependent variable the corresponding figures were 50% and 54%. The major part of the variance in all these models was explained by BA, and only a few percent by all the other independent variables. No significant reduction was found when TEE or daily intakes of calcium or vitamin D were introduced into the models. These results illustrate the importance of including BA, weight and height as independent variables in regression models of TBMC to avoid spurious associations with other variables in the analyses. The results may also indicate that in normal Swedish adolescents environmental factors such as dietary intake of nutrients play a minor role as determinants of bone mineralization. High levels of physical activity and bone mineral measures possibly explain the lack of significant correlations between these variables and do not imply a lack of association.

This pilot study indicates that obese prepubertal children were able to reduce their fat intake to avoid gastrointestinal side effects. Thus, orlistat may be suitable as a component in behaviour-modification programmes for obese children, and the results prompt a placebo-controlled investigation of its effectiveness in promoting weight loss.