When it comes to bugs like bacteria and parasites, we've been trained to think that less is better. But there are some good guys in the microbial world — bugs that do the unglamorous work of keeping us regular and helping to relieve a range of disorders from diarrhea to irritable bowel syndrome (IBS). Now, a new study suggests that the same microbes may even help us stay slim.

In the Proceedings of the National Academy of Science, researchers at the University of Arizona and the Mayo Clinic in Arizona report a very small study of nine individuals — three of normal weight, three who were morbidly obese and three who underwent gastric bypass surgery. The team found that each group harbored a different intestinal zoo of microbes, and that following their surgery, the gastric bypass patients' gut bugs ended up looking much more similar to those of the normal weight patients.

While these results are only preliminary, they do point to an entirely new way that doctors and patients might be able to tackle the growing obesity epidemic in the U.S. "This study suggests that the differences in the organisms may play at least some role in why people lose the weight they do," says Dr. John DiBaise, a gastroenterologist at Mayo Clinic and one of study's authors. "Ultimately, we may not only be able to manipulate the microbes of obese individuals to look like those of normal weight people, but we might also potentially be able to predict a person's susceptibility to obesity."

What might be happening, suspects DiBaise, is that each person's ability to extract energy and store fat from food changes depending on which combination of bugs are living in the gut. Those who are morbidly obese, it seems, tend to nurture bugs that promote the fat storage process, which might be a factor in their excessive weight gain. The bypass patients appeared to follow a similar pattern but in the opposite direction, eating less first and then developing bugs appropriate to that diet. It's not clear how the physical act of reducing food intake drives that change, nor how long-lasting the possible slimming effects of the new bug population will be.

But none of this means that downing the latest probiotic yogurts, which contain certain strains of good gut bacteria, should be the next weight loss craze. For one, says DiBaise, the strains that were dominant in the normal weight people are not the same as those promoted in the popular probiotic yogurts. Second, there is no evidence that probiotic products can do anything about weight loss; the latest scientific studies have shown only that probiotics can relieve antibiotic-related diarrhea, as well as alleviating IBS and aiding regularity. "It is interesting to look at microbial flora," says Lynne McFarland, an epidemiologist at the Puget Sound Veterans Administration Medical Center, who was not affiliated with the study. "But I would not run out and eat a lot of yogurt because of this."

At least, not yet. More studies are needed to follow the same people as they lose weight through diet and exercise, to see if the composition of their gut flora changes — as it did with the gastric bypass patients. What's more, notwithstanding the seemingly cause-and-effect link between gut flora and weight, that relationship can be deceiving; a third factor entirely may be causing both — a diet of highly processed foods, for instance, suggests Dr. David Katz, director of the Yale Prevention Research Center. What's more, says Katz: "Regardless of the variation of gut flora in the population, the entire population is getting heavy. So probiotics might tweak one's personal vulnerability to obesity, but they would not much move the big dial [on the obesity epidemic]," he says. Still, as anyone fighting the numbers on the scale knows, every little bit helps — even something a little as a bacterium.

当谈到细菌和寄生虫的时候，我们习惯性的都认为越少越好。 实际上在微生物界中有一些好虫子的，它们做着枯燥无聊的工作来维持我们的身体正常运转，还能预防从腹泻到肠道紊乱综合症的病症。 现在新的研究发现这些微生物甚至帮助我们保持苗条。

在一项美国国家科学院亚利桑那州大学和马奥诊所的研究者们进行的小范围试验中，有9个被观测者，三个正常体重，三个肥胖症，还有三个要做胃旁路手术的病人。 研究团队发现不同组的人体肠道中的菌群是完全不同的。在手术后，那三个有胃病的人最后的肠道菌群变的和正常体重的病人相近了。

虽然这些结论只是初级的，但它确实为医生和病人降低美国日益增长的肥胖症比率打开了一扇新的大门。作为这项研究的主要研究员，马奥诊所的胃肠病学家约翰.迪拜瑟医生说:“这项研究说明这些微生物肯定在在人们的减肥过程中扮演了什么角色。如果弄得好，我们可能不仅让胖子们的肠道菌群和正常人的一样，还可以预测一个人会不会变胖。”

拜瑟医生怀疑，每个人吸收营养、存储脂肪的能力和自己的肠道菌群的种类组合息息相关。胖子们的似乎在肠道内饲养了一群会提高脂肪存储的微生物才造成了他们的肥胖。而那些胃旁路患者也走了相同的路，不过方向刚好相反，吃的少，也就养成了适合节食的菌群。对于运动和减少食物摄入如何影响这种变化和这些减肥效果能减肥的新菌群能坚持多久还不是很清楚。

但是这些结果不意味着喝含有一些良性菌的最新酸牛乳会成为下一个减肥风潮。拜瑟医生说，首先，人体肠道中的菌群和算牛乳的菌群是不一样的。其次，这些产品和能不能减肥基本没啥关系。最新的研究也只是发现这些饮料可以缓解抗生素相关的腹泻，减轻肠道综合症和稳定肠道。没有参与本研究的皮热老兵健康管理医疗中心的流行病学家林恩.马克弗兰说：“观察微生物菌从是很有意思的，那我也不能因此跑出去吃一大堆酸乳酪啊！”

至少，现在还不行。还需要做更多的试验。观察同一些人在节食和锻炼后他们的肠道菌群组合变化是否和那些胃旁路手术的病人的一样。 还有，尽管肠道菌群和减肥之间看似有因果关系，但这种关系也许具有欺骗性。耶鲁预防研究中心的大卫.卡茨说，可能有第三种因素同时导致了前二者，比如一份对都是高杀菌处理食物的食谱。他还说，“无视人们肠道菌群的种类变化，人们还是在变重，就算它们能减弱人对肥胖趋势，还是改变不了大趋势。”但那些和秤上表针战斗的胖子们还是要抓紧最后的稻草-哪怕这稻草只有细菌那么小。