OBJECTIVE: To investigate the energy metabolism modi®cations induced by energy restriction and weight loss in massively obese adolescents. SUBJECTS: Ten massively obese girls (179 AE 31% of ideal body weight; age, 13.3 ± 16.4 y) after 2 ± 5 weeks on a lowenergy diet and 4.5 ± 11.5 months later, that is, after a substantial weight loss, and eight controls. MEASUREMENTS: Resting energy expenditure (REE) and carbohydrate-induced thermogenesis (CIT) after a sucrose load (by indirect calorimetry), plasma glucose and insulin before and after the sucrose load. RESULTS: After 2 ± 5 weeks on a low-energy diet, REE (7415 AE 904 kJad) was lower than the expected value calculated from the regression equation of REE on fat free mass in controls (P 0.005). After a 37 AE 17% reduction in excess weight, REE decreased (6405 AE 613 kJad) and remained lower than the expected value (P 0.005). At the early stages of weight loss, the area under the plasma glucose response curve was negatively correlated with CIT (r 7 0.80, P 0.01) and was higher in the six obese adolescents with low CIT than in the four with normal CIT (396 AE 52 vs 283 AE 26 mmol.l 71 .min 71 , P 0.01). After substantial weight loss, the area under the plasma insulin response curve decreased by 32% (P 0.02), and both CIT and the area under the plasma glucose response curve became similar in obese patients with low and normal CIT prior to weight loss. CONCLUSION: These results indicate that in massively obese adolescents, REE for fat-free mass is decreased at the very beginning of the process of losing weight and remains decreased as long as energy restriction and weight reduction carry on. They also indicate that the impaired CIT sometimes observed returns to normal after weight reduction suggesting that it is secondary to a decrease in glucose uptake induced by obesity-associated insulin resistance.

BackgroundThe incidence of childhood type 1 diabetes (T1D) incidence is rising in many countries, supposedly because of changing environmental factors, which are yet largely unknown. The purpose of the study was to unravel environmental markers associated with T1D.MethodsCases were children with T1D from the French Isis-Diab cohort. Controls were schoolmates or friends of the patients. Parents were asked to fill a 845-item questionnaire investigating the child’s environment before diagnosis. The analysis took into account the matching between cases and controls. A second analysis used propensity score methods.ResultsWe found a negative association of several lifestyle variables, gastroenteritis episodes, dental hygiene, hazelnut cocoa spread consumption, wasp and bee stings with T1D, consumption of vegetables from a farm and death of a pet by old age.ConclusionsThe found statistical association of new environmental markers with T1D calls for replication in other cohorts and investigation of new environmental areas.Trial registrationClinical-Trial.gov NCT02212522. Registered August 6, 2014. Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-3690-9) contains supplementary material, which is available to authorized users.

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