TSH concentrations are elevated in obese children but are not correlated with the amount of excess body weight or fat. During weight loss, independent of changes in body weight or composition, decreases in elevated serum TSH predict decreases in fasting insulin and HOMA. These findings suggest interventions that target high TSH concentrations during weight loss in obese subjects may improve insulin sensitivity.

Background: It is unclear whether high plasma leptin in obese individuals represents leptin resistance or whether individuals with marked reductions in leptin concentrations in response to weight loss may be at greater risk of regaining weight. Moreover, whether changes in leptin predict metabolic improvements during weight loss is uncertain. Objective: The objective was to prospectively examine associations between plasma leptin, body fat, and weight and metabolic risk factors in obese children during weight loss. Design: In obese children and adolescents [n = 203; mean age: 14.1 y, .98th body mass index (BMI) percentile for age and sex] participating in a 2-mo inpatient weight-loss program, we measured changes in body composition (by dual-energy X-ray absorptiometry), plasma leptin, insulin, and lipids. After discharge, anthropometric measures and plasma leptin were remeasured at 6 (n = 139) and 12 (n = 100) mo. Results: During the 2-mo program, mean (6SD) weight and fat loss were 13.9 6 4.0 kg and 9.2 6 2.5 kg, respectively; and mean plasma leptin decreased by 76%. Weight and fat loss were sustained, and no significant differences in BMI-SD score (SDS) or body composition were found between 12 and 2 mo. Baseline leptin was a negative predictor for percentage fat loss at 2, 6, and 12 mo (P , 0.05). The percentage change in leptin during the 2-mo intervention positively correlated with the relative change in fasting insulin, the relative change in LDL cholesterol at 2 mo, percentage fat loss, and change in BMI-SDS at 2 and 6 mo (P , 0.02). Conclusions: Even in obese children with strongly elevated baseline leptin, large leptin reductions that predict short-and long-term loss of body fat and improvements in lipids and insulin sensitivity can be achieved. Thus, increased plasma leptin in obese children may not necessarily reflect leptin resistance; many children appear to remain leptin sensitive at this age.Am J Clin Nutr 2011;93:695-702.

Background and objectives: A time-restricted diet is one of the various ways to improve metabolic condition and weight control. However, until now, there have been few pieces of evidence and research to verify the methods and effectiveness of time-restricted diets on metabolic improvement and health promoting. We designed this study to make a healthy diet program and to verify the effectiveness of a time-restricted diet on general health, including sleep and metabolism, in healthy volunteers. Materials and Methods: This study was conducted in healthy adults who are obese but do not have related metabolic disease. Fifteen participants were recruited. Before and after this program, serologic tests including ketone level, questionnaires—daytime sleepiness evaluation such as the Epworth sleepiness scale and the Stanford sleepiness scale, the Korean version of the Pittsburgh sleep questionnaire index, STOP BANG to evaluate sleep apnea, the Hospital Anxiety and Depression Scale for emotion/sleep—and polysomnography (PSG) were conducted to evaluate the effects on sleep of the program. They were divided into two groups based on ketone levels that could reflect the constancy of participation in this study. We analyzed the before and after results of each group. Results: Fifteen participants (nine males and six females) completed this program without significant adverse events. Body weight after this program decreased to 78.2 ± 14.1 from 82.0 ± 15.6 kg (p = 0.539), and BMI decreased to 27.9 ± 3.8 from 29.3 ± 4.6 kg/m2 (p = 0.233). Weight loss was observed in 14 subjects except 1 participant. The results from questionnaires before and after this were not significant changes. They were classified into high/low-ketone groups according to the ketone level of the participants. In the results of the PSG, the apnea hypopnea index (25.27 ± 12.67→15.11 ± 11.50/hr, p = 0.25) and oxygen desaturation (18.43 ± 12.79→10.69 ± 10.0/hr, p = 0.004), which are indicators of sleep apnea, also improved in the high-ketone group, compared with the low-ketone group. Satisfaction interviews for this restricted diet program showed that 86% of the participants were willing to participate in the same program again. Conclusion: The time-restricted diet was successful in weight loss for a period of 4 weeks in obese participants, which did not affect the efficiency and architecture of sleep. In addition, successful weight loss and significant improvement of sleep apnea were showed in the high-ketone group. Further research is needed to demonstrate mechanisms for weight loss, sleep apnea, and time-restricted diets.

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