Rowett Institute of Nutrition and Health, University of Aberdeen, UK.
J Clin Gastroenterol. 2011 Nov;45 Suppl:S128-32. doi: 10.1097/MCG.0b013e31821f44c4.
Gut microorganisms have the potential to influence weight gain and fat deposition through a variety of mechanisms. One factor is the ability of microorganisms in the large intestine to release energy by fermenting otherwise indigestible components of the diet ("energy harvest"). This energy becomes available to the host indirectly through the absorption of microbially produced short-chain fatty acids. Energy recovery from fiber will be largely determined by dietary intake and gut transit, but can also depend on the makeup of the gut microbiota. The species composition of the gut microbiota changes with diet composition, as has been shown in studies with obese individuals after reduced carbohydrate weight loss diets, or diets containing different nondigestible carbohydrates. There is conflicting evidence, however, on the extent to which gut microbiota composition differs between obese and nonobese humans. In contrast, there is increasing evidence to suggest that gut microorganisms and their metabolic products can influence gut hormones, inflammation, and gut motility. Any changes in gut microbiota composition that influence energy expenditure, satiety, and food intake have the potential to alter weight gain and weight loss, but a better understanding of the impact of different members of the gut microbial community upon host physiology is needed to establish these relationships.
肠道微生物群通过多种机制具有影响体重增加和脂肪沉积的潜力。一个因素是大肠中微生物通过发酵饮食中原本不可消化的成分（“能量收获”）释放能量的能力。这种能量通过吸收微生物产生的短链脂肪酸间接地可供宿主使用。纤维的能量回收在很大程度上取决于饮食摄入和肠道转运，但也可能取决于肠道微生物群的组成。正如在接受低碳水化合物减肥饮食或含有不同不可消化碳水化合物的饮食的肥胖个体的研究中所表明的那样，肠道微生物群的物种组成随饮食组成而变化。然而，关于肥胖者和非肥胖者之间肠道微生物群组成在多大程度上存在差异，证据相互矛盾。相比之下，越来越多的证据表明，肠道微生物及其代谢产物可以影响肠道激素、炎症和肠道蠕动。任何影响能量消耗、饱腹感和食物摄入的肠道微生物群组成的变化都有可能改变体重增加和体重减轻，但需要更好地了解肠道微生物群落的不同成员对宿主生理学的影响，以建立这些关系。
