Sex steroids in relation to sexual and skeletal maturation in obese male adolescents.

BACKGROUND: Childhood obesity is associated with an accelerated skeletal maturation. However, data concerning pubertal development and sex steroid levels in obese adolescents are scarce and contrasting. OBJECTIVES: To study sex steroids in relation to sexual and skeletal maturation and to serum prostate specific antigen (PSA), as a marker of androgen activity, in obese boys from early to late adolescence. METHODS: Ninety obese boys (aged 10-19 y) at the start of a residential obesity treatment program and 90 age-matched controls were studied cross-sectionally. Pubertal status was assessed according to the Tanner method. Skeletal age was determined by an x-ray of the left hand. Morning concentrations of total testosterone (TT) and estradiol (E2) were measured by liquid chromatography-tandem mass spectrometry, free T (FT) was measured by equilibrium dialysis, and LH, FSH, SHBG, and PSA were measured by immunoassays. RESULTS: Genital staging was comparable between the obese and nonobese groups, whereas skeletal bone advancement (mean, 1 y) was present in early and midadolescence in the obese males. Although both median SHBG and TT concentrations were significantly (P < .001) lower in obese subjects during mid and late puberty, median FT, LH, FSH, and PSA levels were comparable to those of controls. In contrast, serum E2 concentrations were significantly (P < .001) higher in the obese group at all pubertal stages. CONCLUSION: Obese boys have lower circulating SHBG and TT, but similar FT concentrations during mid and late puberty in parallel with a normal pubertal progression and serum PSA levels. Our data indicate that in obese boys, serum FT concentration is a better marker of androgen activity than TT. On the other hand, skeletal maturation and E2 were increased from the beginning of puberty, suggesting a significant contribution of hyperestrogenemia in the advancement of skeletal maturation in obese boys.

Bone size and bone strength are increased in obese male adolescents.

CONTEXT: Controversy exists on the effect of obesity on bone development during puberty. OBJECTIVE: Our objective was to determine differences in volumetric bone mineral density (vBMD) and bone geometry in male obese adolescents (ObAs) in overlap with changes in bone maturation, muscle mass and force development, and circulating sex steroids and IGF-I. We hypothesized that changes in bone parameters are more evident at the weight-bearing site and that changes in serum estradiol are most prominent. DESIGN, SETTING, AND PARTICIPANTS: We recruited 51 male ObAs (10-19 years) at the entry of a residential weight-loss program and 51 healthy age-matched and 51 bone-age-matched controls. MAIN OUTCOME MEASURES: vBMD and geometric bone parameters, as well as muscle and fat area were studied at the forearm and lower leg by peripheral quantitative computed tomography. Muscle force was studied by jumping mechanography. RESULTS: In addition to an advanced bone maturation, differences in trabecular bone parameters (higher vBMD and larger trabecular area) and cortical bone geometry (larger cortical area and periosteal and endosteal circumference) were observed in ObAs both at the radius and tibia at different pubertal stages. After matching for bone age, all differences at the tibia, but only the difference in trabecular vBMD at the radius, remained significant. Larger muscle area and higher maximal force were found in ObAs compared with controls, as well as higher circulating free estrogen, but similar free testosterone and IGF-I levels. CONCLUSIONS: ObAs have larger and stronger bones at both the forearm and lower leg. The observed differences in bone parameters can be explained by a combination of advanced bone maturation, higher estrogen exposure, and greater mechanical loading resulting from a higher muscle mass and strength.

Metabolic disregulation in obese adolescents with sleep-disordered breathing before and after weight loss.

OBJECTIVE: Sleep-disordered breathing (SDB) is prevalent in obesity. Weight loss is one of the most effective treatment options. The aim was to assess the association of SDB and metabolic disruption before and after weight loss. DESIGN AND METHODS: Obese adolescents were included when entering an in-patient weight loss program. Fasting blood analysis was performed at baseline and after 4-6 months. Sleep screening was done at baseline and at follow-up in case of baseline SDB. RESULTS: 224 obese adolescents were included. Median age was 15.5 years (10.1-18.0) and mean BMI z-score was 2.74 ± 0.42. About 30% had SDB at baseline (N = 68). High-density lipoprotein (HDL)-cholesterol was associated with mean nocturnal oxygen saturation () (partial r = 0.21; P = 0.002). Aspartate aminotransferase (ASAT) and alanine aminotransferase were related with oxygen desaturation index (partial r = -0.15; P = 0.03 and partial r = -0.15; P = 0.02), but this became insignificant after correction for sex. After weight loss, 24% had residual SDB. Linear regression showed an association between ASAT and (partial r = -0.34; P = 0.002). There were no significant correlations between improvements in laboratory measurements and sleep parameters. HDL-cholesterol improved in relation with the decrease in BMI z-score. CONCLUSION: SDB at baseline was associated with higher levels of liver enzymes and lower HDL-cholesterol concentration. Improvements in sleep parameters were not associated with improvements in laboratory measurements.

Post-treatment phone contact: a weight maintenance strategy in obese youngsters.

This study investigated the effect of post-treatment phone contact on weight-loss maintenance and activity behaviour in obese youngsters. In all, 20 patients who completed a weight reduction program were randomly assigned to a 5-month maintenance programme (experimental) or control condition. Following the maintenance programme, patients sent a weekly activity diary to the therapist, who in turn phoned them biweekly to discuss their activities. Body weight, stature and physical activity were measured before and after the maintenance programme. The control group showed a continuous increase in overweight after initial treatment, while the experimental group showed a steep increase during the summer holidays (no intervention), but this increase slowed down during the maintenance programme (P<0.05). Moderate-to-high intensity activities increased during the maintenance programme in the experimental group, but decreased in the control group (P<0.001). In conclusion, post-treatment phone contact appears to have the potential to be an effective maintenance strategy in obese youngsters.

Effects of distraction on treadmill running time in severely obese children and adolescents.

OBJECTIVE: (1) To examine the effects of attentional distraction on running time in an incremental treadmill test in obese youngsters; (2) to investigate whether distraction works at the same extent at the beginning and at the end of residential treatment; and (3) to explore the underlying mechanisms of the possible distraction effects. METHODS: Thirty severely obese youngsters (10 boys, 20 girls, age range 9-17) who were following a 10 month residential treatment, performed a treadmill test until exhaustion in four different sessions using a within subjects design. The two sessions at the beginning of the treatment and the two sessions at the end the treatment were counterbalanced, one with attentional distraction (music) and one without distraction. RESULTS: Obese youngsters ran significantly longer during distraction. This distraction effect seemed to be larger at the beginning compared to at the end of obesity treatment. The absence of differences between the condition with music and the condition without music on perceived bodily symptoms is in line with the idea that it took longer to perceive sufficient bodily sensations to decide to stop the treadmill test in the distraction condition. This interpretation is further corroborated by the physiological data indicating a superior peak performance in the condition with distraction. CONCLUSIONS: Attentional distraction has a positive effect on perseverance in obese youngsters. Further research has to show the usefulness of attentional distraction as a technique to increase exercise adoption and adherence in obesity treatment.