Effect of lifestyle changes on whole-body protein turnover in obese adolescents

Abstract

OBJECTIVE:To investigate the effect of lifestyle changes on whole-body protein turnover (WBPT) in obese adolescents. DESIGN/METHODS: Randomized and controlled nonpharmacological intervention study of WBPT in obese adolescents using stable isotope dilution techniques. SUBJECTS AND MEASUREMENTS:We studied a total of 21 adolescents (11 boys and 10 girls, matched for their pubertal status) of which 15 were obese (age ¼ 15.870.4 y old and BMI ¼ 38.673.3 kg/m 2 ) and six were lean controls (age ¼ 16.070.4 y old and BMI ¼ 21.371.2 kg/m 2 ). The obese subjects were subjected to a randomized controlled lifestyle intervention program that involved moderate physical activity and diet changes for 3 months. A group of lean age-matched subjects was also studied at baseline to compare the WBPT in obese and lean adolescents. The studies were performed during a primed, continuous infusion of L-[1-13 C]leucine. Leucine appearance rate (Leu Ra) was used as an index of whole protein breakdown and the nonoxidative portion of leucine disposal (NOLD) as an index of whole-body protein synthesis. RESULTS: The obese groups showed significantly higher body mass index (BMI), fat mass (FM), percent body fat (%BF), fat-free mass (FFM), resting energy expenditure (REE) and WBPT compared to the lean controls. The intervention program resulted in a redistribution of the parameters of body composition without apparent changes in BMI or body weight. There was a significant decrease in WBPT in the obese intervention group, but not in the obese control group. Insulin levels also decreased significantly in the obese group after intervention but not in the obese control group, whereas the glucose concentrations remained normal in all groups at baseline and also after intervention/or control. CONCLUSIONS: Results from the current study suggest: (i) abonormalities of protein metabolism occur early in the clinical course of obesity and (ii) these abnormalities are modifiable by moderate lifestyle changes in obese adolescents. The mechanism for these changes in WBPT in obese adolescents as well as their impact on specific cardiovascular risk factors and turnover of specific proteins will require further investigation.

Effectiveness of Lifestyle Interventions in Child Obesity: Systematic Review With Meta-analysis

“…Twenty-four studies did not specify the method of randomization. [22][23][24]26,28,29,31,33,36,39,42,45,46,[48][49][50][51][63][64][65][66][67][68]71 Details of allocation concealment 23,24,26,28,29,31,[33][34][35][36]41,[43][44][45][46]50,51,63,[66][67][68]71 and study blinding 24,[27][28][29][30][31]…”

“…23 Eighteen studies targeted obese children exclusively, 22,23,26,28,29,31,34,38,[40][41][42]44,46,51,[64][65][66]71 whereas the others targeted both overweight and obese children. Most studies (n = 14) were conducted in a hospital environment, 22,25,29,32,36,38,[40][41][43][44]46,63,65,68 followed by the community (n = 6), 23,27,[33][34][35]51 school (n = 6), 26,42,[48][49][50]64 and primary care setting (n = 6). 30,37,39,47,67,…”

“…Twelve studies did not follow the participants after the intervention program ended. [22][23][24]26,28,29,31,32,36,63,64,68 For the comparison of lifestyle intervention with usual care (n = 11), the intervention lengths varied from 3 months to 1 year, and 6 studies conducted subsequent follow-up, [41][42][43]45,65,69 ranging from 2 months to 4 years from the end of the active intervention component. Among the 5 written information studies, 1 had a varied intervention length, 2 had an intervention length of 6 months, 48,49 and another 2 were 1-year 50,51 intervention programs with the outcome evaluation at the end of the intervention.…”

“…Nearly half of the studies were conducted in the United States (n = 18), 22,24,29,33,41,[46][47][48][49]50,56,63,64,[66][67][68][69]71 5 in Australia, 25,30,[35][36][37] and the others in Israel (n = 3), 39,43,44 Germany (n = 2), 32,51 the United Kingdom (n = 2), 34,40 Belgium, 65 China, 28 Finland, 42 Iran, 45 Korea, 31 Mexico, 38 Taiwan, 26 and Tunisia. 23 Eighteen studies targeted obese children exclusively, 22,23,26,28,29,31,34,38,[40][41][42]44,46,…”

“…Most studies (n = 14) were conducted in a hospital environment, 22,25,29,32,36,38,[40][41][43][44]46,63,65,68 followed by the community (n = 6), 23,27,[33][34][35]51 school (n = 6), 26,42,[48][49][50]64 and primary care setting (n = 6). 30,37,39,47,67,69 Thirteen studies were conducted in children, 25,30,[33][34][35]37,[40][41][42]44,47,50,66 7 in adolescents, [22][23][24]28,29,31,…”