Bacteria in Gut Linked to Obesity

Certain Bacteria May Pile on the Calories in Obese People

By Miranda Hitti
WebMD Health News

Reviewed by Louise Chang, MD

Dec. 21, 2006 -- Obese people may be getting more calories than they bargain for from their food because of natural bacteria in their gut.

A new study shows that a certain type of gut bacterium is more common in obese people than in leaner people.

That particular type of bacterium is good at releasing calories from food. An abundance of those bacteria may mean that obese people are getting more calories out of their food than lean people, possibly adding on pounds.

The findings may one day lead to a new obesitytreatment, write Jeffrey Gordon, MD, and colleagues in Nature.

Gordon works at Washington University School of Medicine in St. Louis as a professor and director of the Center for Genome Sciences.

Gut Bacteria

It's normal to have bacteria in your gut; they help break down food.

There are many types of gut bacteria. Gordon's study suggests that the bacterial mix differs in obese and lean people.

Gordon's team studied two types of gut bacteria in 12 obese people.

They found that one type of gut bacterium was more common in lean people than in obese people; the other type more common in obese people than in lean people.

The obese participants went on a yearlong diet. As they lost weight, their gut bacteria levels started to look more like the gut bacteria levels of lean people.

Gut Bacteria Test

Gordon and colleagues investigated further. They transplanted the gut bacteria from either obese mice or lean mice into mice of normal weight.

Mice that received gut bacteria from obese mice gained more body fat over two weeks than those that got bacteria from lean mice, even though their diets were the same and they ate the same amount of chow.

The gut bacteria in the obese mice are more effective at releasing calories from food, the study shows.

If that's found to also be true in people, it could offer a new avenue for treating for excess weight.

The gut bacteria theory is a "potentially revolutionary idea," states a journal editorial. The editorialists note that many research questions need to be answered before anyone starts trying to tinker with gut bacteria to lose weight.

Meanwhile, a healthy diet and sensible exercise program are the tried-and-true ways to shed extra pounds. Check with your doctor before launching a weight loss program.

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