Effects of exercise-induced weight loss on acylated and unacylated ghrelin in overweight children
ABSTRACT Controversial data on ghrelin concentration during exercise in human subjects have been published. We tested the hypothesis that exercise could affect acylated ghrelin (AG) and unacylated ghrelin (UAG), which could partly explain the previously reported inconsistent findings on the association of exercise with changes in ghrelin.
A prospective randomized study.
We randomized 17 overweight volunteers (11-year-old boys) to a 12-week combined exercise group (EG, n = 8) or control group (CG, n = 9). At baseline, 1, 4 and 12 weeks, we measured body weight and composition, insulin, leptin, total ghrelin and acylated ghrelin.
Compared with the CG, body weight, percentage body fat and homeostatic model assessment (HOMA) indices were significantly lower throughout the 12 weeks in the EG. Total ghrelin and UAG levels gradually increased to 131.9 +/- 5.2% and 130.4 +/- 5.2% of baseline, respectively, at week 12 in the EG, whereas AG concentration remained unchanged throughout the 12 weeks both within each group and between the groups. At week 12, there were differences in the total ghrelin level and UAG level between the groups.
This study shows an increase in unacylated acylated ghrelin and unchanged acylated ghrelin after a 12-week combined exercise programme in overweight children. These findings provide evidence of favourable effects of exercise on improving energy metabolism.
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ABSTRACT: Aims/IntroductionThe interactive effects of resistance training and dietary protein on hormonal responses in adults are not clear and remain controversial. We tested the effect of an isocaloric high-protein diet on body composition, ghrelin, and metabolic and hormonal parameters during a 12-week resistance training program in untrained healthy young men.Material and Methods We randomized 18 healthy young men to a standard diet (ST group) or an isocaloric high protein diet (HP group). Both groups participated in a 12-week resistance exercise program. We measured body composition, lipid profile, homeostatic model assessment of insulin resistance (HOMA-IR) indices, total ghrelin, and exercise-related hormones at baseline and 12 weeks.ResultsIn the HP group, lean body mass (LBM), total ghrelin, growth hormone, testosterone and cortisol levels showed an increase, whereas body fat percentage and HOMA-IR showed a decrease at 12 weeks, compared with baseline (P ≤ 0.05). In the ST group, no changes in these parameters were observed during the 12-week period. During the 12-week period, significant differences in the pattern of change of LBM (P = 0.032), total ghrelin (P = 0.037), HOMA-IR (P = 0.040) and high-density lipoprotein cholesterol (P = 0.011) over time were observed between the groups.Conclusions The findings of the present study suggest that an isocaloric high-protein diet can ameliorate body composition, metabolic profiles and energy metabolism during a 12-week scheduled resistance training program in untrained healthy young men. This trial was registered with ClinicalTrials.gov (no. NCT01714700).03/2014; 5(2). DOI:10.1111/jdi.12148This article is viewable in ResearchGate's enriched formatRG Format enables you to read in context with side-by-side figures, citations, and feedback from experts in your field.
SourceAvailable from: Raziye Gul Tiryaki-Sonmez[Show abstract] [Hide abstract]
ABSTRACT: This study investigated the effects of a long bout of aerobic exercise on hunger and energy intake and circulating levels of leptin and acylated ghrelin. Ten healthy male subjects undertook two, 4 h trials in a randomized crossover design. In the exercise trial subjects ran for 105 min at 50% of maximal oxygen uptake and the last 15 min at 70% of maximal oxygen uptake followed by a 120 min rest period. In the control trial, subjects rested for 4 h. Subjects consumed a buffet test meal at 180 min during each trial. Hunger ratings, acylated ghrelin, leptin, glucose and insulin concentrations were measured at 0, 1, 2, 3 and 4 h. No differences were found at baseline values for hunger, acylated ghrelin, leptin, insulin and glucose for both trials (p > 0.05). The estimated energy expenditure of the exercise trial was 1550 ± 136 kcal. Exercise did not change subsequent absolute energy intake, but produced a significant decrease (p < 0.05) in relative energy intake. A two-way ANOVA revealed a significant (p < 0. 05) interaction effect for hunger and acylated ghrelin. In conclusion, this exercise regimen had a positive effect on reducing appetite which is related to reduced acylated ghrelin responses over time. This finding lends support for a role of exercise in weight management. Key pointsPhysical exercise is a strategy used to counteract obesity, since it lowers the energetic balance by increasing energy expenditure. However, because any energy expended in exercise elevates the intensity of hunger and drives food consumption, it is pertinent to ask how effective exercise could be in helping people to lose weight or to prevent weight gain.The effects of exercise on hunger sensations and food intake are fairly controversial and depend on the intensity and duration of exercise.120 min prolonged treadmill exercise with mix intensity, temporarily decreased hunger sensations, acylated ghrelin and relative energy intake.Variations in exercise intensity should theoretically be a useful means of weight loss.Journal of sports science & medicine 01/2011; 10(2):283-91. · 0.90 Impact Factor
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ABSTRACT: BACKGROUND AND OBJECTIVES:The prevalence of obesity and diabetes is increasing among children, adolescents, and adults. Although estimates of the efficacy of exercise training on fasting insulin and insulin resistance have been provided, for adults similar estimates have not been provided for youth. This systematic review and meta-analysis provides a quantitative estimate of the effectiveness of exercise training on fasting insulin and insulin resistance in children and adolescents.METHODS:Potential sources were limited to peer-reviewed articles published before June 25, 2013, and gathered from the PubMed, SPORTDiscus, Physical Education Index, and Web of Science online databases. Analysis was limited to randomized controlled trials by using combinations of the terms adolescent, child, pediatric, youth, exercise training, physical activity, diabetes, insulin, randomized trial, and randomized controlled trial. The authors assessed 546 sources, of which 4.4% (24 studies) were eligible for inclusion. Thirty-two effects were used to estimate the effect of exercise training on fasting insulin, with 15 effects measuring the effect on insulin resistance. Estimated effects were independently calculated by multiple authors, and conflicts were resolved before calculating the overall effect.RESULTS:Based on the cumulative results from these studies, a small to moderate effect was found for exercise training on fasting insulin and improving insulin resistance in youth (Hedges' d effect size = 0.48 [95% confidence interval: 0.22-0.74], P < .001 and 0.31 [95% confidence interval: 0.06-0.56], P < .05, respectively).CONCLUSIONS:These results support the use of exercise training in the prevention and treatment of type 2 diabetes.PEDIATRICS 12/2013; 133(1). DOI:10.1542/peds.2013-2718 · 5.30 Impact Factor