Weight loss and changes in energy metabolism in massively obese adolescents

Abstract

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.

Changes in fat mass, fat-free mass and aerobic fitness in severely obese children and adolescents following a residential treatment programme

“…The incorporation of more resistance training in our programme may help further diminish the loss of FFM. Our data are comparable with the results of another residential treatment described by Tounian et al [50]. This programme, which consisted of a 1400-1600 kcal diet in combination with physical activity, resulted in absolute weight-loss of 68% FM (11.6 kg) and 32% FFM (5.4 kg) as estimated from change in skinfold thickness.…”

Programming towards Childhood Obesity

“…This hypothesis is more plausible than a dysregulation of their adipostat inducing an excess weight gain when the children eat more than they expend. Indeed, when obese children try to lose weight, their adipostat actively resists by stimulating appetite [7] and reducing energy expenditure [8] in order to maintain the elevated body weight. In obese children, this programmed, elevated weight gain is also mainly influenced by genes.…”

Longitudinal changes in activity patterns, physical capacities, energy expenditure, and body composition in severely obese adolescents during a multidisciplinary weight-reduction program

“…Restriction of energy intake results in larger energy deficits than exercise alone in treatments of children and adolescent obesity. 12 However, hypocaloric diets may slow down growth and induce reductions in resting metabolic rate in proportion to the decreases in FFM, 13,14 which favors weight regain after cessation of the dietary treatment. 15 Several studies in children and adolescents have shown that moderate energy restriction associated with exercise and behavioral intervention induced significant body weight (BW) and FM losses without significant reductions in FFM and basal metabolic rate (BMR).…”