Diet Hit A Snag? Your Gut Bacteria May Be Partly To Blame : The Salt Scientists are learning more about how our gut microbes may influence dieting. A small new study finds successful dieters have a different mix of bacteria than less-successful dieters.

Diet Hit A Snag? Your Gut Bacteria May Be Partly To Blame

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So if you've ever been on a diet but you didn't lose the weight you would hope to lose, your gut bacteria might be part of the problem. NPR's Allison Aubrey reports on how the microbes in our guts may either help or hinder weight loss.

ALLISON AUBREY, BYLINE: This is kind of an odd thing to think about, but, the bacteria that live in our guts can actually do us a favor. They eat what we can't. Martin Blaser is a professor at NYU Langone Medical Center. He says, consider what happens when we eat an apple. We digest most of it...

MARTIN BLASER: But there's a certain part of the apple that can't be absorbed. We don't have the right enzymes to digest every bit of it, but our bacteria can.

AUBREY: After the bacteria consume what we can't, they produce byproducts that we can digest, and that's another source of calories for us.

BLASER: Somewhere between 5 percent and 15 percent of all our calories come from that kind of digestion, where the microbes are providing energy for us that we couldn't ordinarily get. And, you know, if times were bad, if we were starving, we would really welcome that.

AUBREY: But these days, when many people want to lose weight, we may not want these extra calories the microbes give us. Researchers at the Mayo Clinic in Minnesota wanted to know if they could identify certain types of bacteria that might influence the success of dieting. Purna Kashyap, a gastroenterologist, helped to lead the study. It included people who were enrolled in a one-year lifestyle program. They were counseled to follow a low-calorie diet and agreed to be monitored closely.

PURNA KASHYAP: We started with the premise that people have different microbial makeups in the gut, and that could influence how well they do with the dieting regimen.

AUBREY: And it turns out when Kashyap and his team compared the dieters who were successful with those who were not, they did find differences.

KASHYAP: We found that people who lost at least 5 percent of their body weight had a different gut bacteria as compared to those who did not lose 5 percent of their body weight.

AUBREY: For instance, they found an abundance of a bacteria called Dialister in the guts of people who did not lose much weight, and another type of bacteria was high in successful dieters. Kashyap says, down the road, if they can show the same results in a larger group of dieters, they'd like to use this information to help people lose weight.

KASHYAP: What you would hope to do is to be able to individualize care for people, and we would also try to develop new probiotics which we can use to change the microbial makeup.

AUBREY: But manipulating the mix of microbes in your gut is easier said than done, according to NYU's Martin Blaser. It's complicated, he says.

BLASER: In part, it depends how lucky we'll be. Whether the organisms that we think are beneficial, we can cultivate them well so that they could become next year's probiotics, that remains unknown.

AUBREY: He says if it's possible, it's still some years off. Allison Aubrey, NPR News.

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