明明吃的不算多，可还是逢年过节胖三斤。或许，增加的体重秤数字还真不能怪你，而是肠胃里微生物惹的祸！
一篇发表在《微生物组》 （Microbiome） 杂志上的研究发现，约40%参与者肠胃中的微生物会从食物中提取更多的能量，从而导致发胖。研究人员根据对丹麦人的粪便及其中微生物的分析，研究了他们从食物中获取多少能量。
The new study, published in the journal Microbiome, was led by experts at the University of Copenhagen's Department of Nutrition, Exercise and Sports. Researchers have studied how much energy Danish people take from their food, based on analysis of their faeces and the microbes within. They found roughly 40 per cent of the participants have microbes that on average extract more energy from food compared to the other 60 per cent.
作者亨利克·罗格教授 （Henrik Roager） 表示 ：“我们可能找到了一些人体重增加的关键，尽管他们没有吃得更多或有任何不同，但是还需要进一步调查。”
"We may have found a key to understanding why some people gain more weight than others, even when they don't eat more or any differently, but this needs to be investigated further," said study author Professor Henrik Roager.
在这项研究中，专家们分析了参与者的粪便样本中的肠道微生物群，肠道中有数万亿的微生物群。研究人员将肠道微生物群描述为“肠道中的整个星系”，每克粪便中有惊人的1000亿种微生物。
For the study, the experts analysed the gut microbiota – the trillion-strong community of microorganisms in the gut – from participants' stool samples. The researchers describe the gut microbiota as "like an entire galaxy in our gut", with a staggering 100 billion of them per gram of faeces.
研究小组研究了85名22至66岁的超重丹麦人的粪便中的残留能量，以估计他们的肠道微生物从食物中提取能量的效率如何。
The research team studied the residual energy in the faeces of 85 overweight Danes aged 22 to 66 to estimate how effective their gut microbes were at extracting energy from food.
同时，他们绘制了每个参与者的肠道微生物组成图。参与者根据其肠道微生物的组成被分为三组：“B型”、“R型”和“P型”。
At the same time, they mapped the composition of gut microbes for each participant. Participants were divided into three groups, based on the composition of their gut microbes — "B-type", "R-type" and "P-type".
图源：Microbiome
B型的碳水化合物 （MACs） 含量较低，这种类型可以与西方的生活方式联系在一起，这些碳水化合物通常存在于水果和蔬菜中，而P型则与富含碳水化合物的饮食有关。
B-type has repeatedly been linked with a Western lifestyle low in microbiota-accessible carbohydrates (MACs) typically found in fruits and vegetables, compared with P-type, for example, linked with a diet rich in MACs.
专家们发现，在40%的参与者中看到的所谓B型成分，更有效地从食物中提取营养物质。
The so-called B-type composition (dominated by Bacteroides bacteria), seen in 40 per cent of the participants, was more effective at extracting nutrients from food, the experts found.
研究人员还发现，那些从食物中提取最多能量的人平均体重增加了10%，相当于多了9公斤。
The researchers also found that those who extracted the most energy from food weighed 10 per cent more on average, amounting to an extra nine kilograms.
图源：视觉中国
在B型人中，提取营养物质的有效性使他们从相同数量的食物中获得更多的热量，从而可能导致肥胖。
The effectiveness of extracting nutrients in in B-type people may result in more calories being available from the same amount of food – possibly leading to obesity.
罗格教授称，“细菌对食物的新陈代谢以短链脂肪酸等形式提供额外的能量，我们的身体可以把这些分子作为供能的燃料”。但是，“如果我们的摄入量超过了消耗量，那么随着时间的推移，肠道细菌提供的额外能量可能会增加肥胖的风险”。
"Bacteria's metabolism of food provides extra energy in the form of, for example, short-chain fatty acids – molecules that our body can use as energy-supplying fuel," said Professor Roager. "But if we consume more than we burn, the extra energy provided by the intestinal bacteria may increase the risk of obesity over time."
研究人员还研究了有着类似饮食习惯的参与者的食物从口腔、消化系统和直肠的旅程时间。
The researchers also studied the duration of the food's journey from mouth, digestive system and rectum for each participant, all of whom had similar dietary patterns.
他们假设，那些消化道旅行时间较长的人将是那些从食物中提取最多的能量的人，但研究发现情况恰恰相反。
They'd hypothesised that those with longer digestive travel times would be the ones who extracted the most energy from their food – but the study found the opposite.
携带B型肠道细菌 （提取最多能量的类型）的 参与者们吃下的食物在胃肠系统中的通过速度也最快。
Participants with the B-type gut bacteria (the type associated with extracting the most energy) also had the fastest passage through the gastrointestinal system.
图源：视觉中国
研究小组说：“尽管从理论上讲，较慢的肠道运输将允许更多的能量提取，但粪便的能量密度与预期的相反，与肠道运输时间呈正相关。”
"Although slower intestinal transit would theoretically allow for more energy extraction, the stool energy density was, opposite of what would be expected, positively associated with intestinal transit time," the team say.
尽管科学家们只使用了来自丹麦参与者的少数样本，但这一发现或适用于全球其他人口。
Although the scientists only used a small sample of Danish participants, it's possible the findings could be applied to other global populations.
图源：视觉中国
总的来说，研究结果表明，超重可能不仅仅与一个人的饮食健康程度或运动量有关，还可能与人体肠道中的微生物有关系。
Overall, the results indicate that being overweight might not just be related to how healthily one eats or the amount of exercise one gets, but it may also have something to do with the microbes in our gut.
所以，易胖可能是你 肠道中的微生物太高效了……
编辑：朱迪齐
实习生：侯琼
来源：每日邮报