The effect of long-term caloric restriction and dietary fibre on energy expenditure, acylated ghrelin, total ghrelin and adipose tissue hormones

饮食因素可能会影响减肥的效率和随后的体重维持。Ghrelin是一种主要由胃分泌的肽类激素，是生长激素分泌型受体的内源性配体，主要有酰化和去酰化两种分子形式。生长激素释放肽的作用是维持体重在一个稳定的状态，这两种分子形式具有抵消作用，相对于能量平衡。短期研究表明，膳食纤维减少餐后酰化生长激素释放肽，但其在长期热量限制中的作用仍不清楚。脂肪组织分泌的其他激素也参与能量平衡，如瘦素、脂联素和脂联素，主要通过胰岛素作用。在本项目中，进行了一项为期12个月的随机对照长期热量限制试验，以研究热量限制（CR）对低脂或低血糖指数饮食的代谢影响，以及它们如何被膳食纤维调节。超重受试者（n = 60）将被随机分配至低脂饮食或低血糖指数饮食。此外，每组中的一半将服用纤维补充剂（20 g/d）。该研究的目的是调查膳食纤维是否（1）在减肥过程中抑制ghrelin的增加，（2）对脂联素，瘦素和glycogen水平有有益的影响，（3）防止体重反弹。在第二项试验中，在超重受试者中检查了CR 6个月至70%或80%的体重维持能量需求对总能量消耗（TEE）、静息代谢率以及酰化和去酰基生长素释放肽的影响（n = 80）。这项研究将是第一个长期试验，重复测量TEE，重点是ghrelin分泌，对于了解体重调节和预防体重反弹将是重要的。(1560字符）。

Dietary factors may influence the efficiency of weight loss and subsequent weight maintenance. Ghrelin, a peptide hormone secreted primarily in the stomach and endogenous ligand of growth-hormone secretague receptor, has two major molecular forms: acylated and desacyl ghrelin. Ghrelin acts to maintain body weight in a steady state and both molecular forms have counteracting roles with respect to energy balance. Short-term studies have shown that dietary fibre decreases postprandial acylated ghrelin, but its role in long-term caloric restriction remains unclear. Other hormones secreted by adipose tissue are also involved in energy balance such as leptin, resistin and adiponectin, mainly via insulin action. In the present project, a randomized controlled long-term caloric restriction trial is conducted over a 12 month period to investigate the metabolic effects of caloric restriction (CR) to either, a diet low in fat or low in glycemic index and how they are modulated by dietary fibre. Overweight subjects (n = 60) will be randomly assigned to either, a diet low in fat or low in glycemic index. Additionally, half of each group will take a fibre supplement (20 g/d). The aim of the study is to investigate whether dietary fibre (1) suppresses ghrelin increase during weight loss, (2) has beneficial effects on adiponectin, leptin and resistin levels and (3) prevents weight regain. In a second trial, the effects of CR for 6 months to either, 70 or 80 % of weight maintenance energy requirements on total energy expenditure (TEE), resting metabolic rate and acylated and desacyl ghrelin is examined in overweight subjects (n = 80). This study will be the first long-term trial with repeated measures of TEE focussing on ghrelin secretion and will be important for the understanding of weight regulation and prevention of weight regain. (1560 characters).