12 Things You Need to Know About Glucomannan—the Hottest Weight Loss Pill Right Now

Glucomannan is the new "it" weight loss supplement. Advocates say it can help shed unwanted pounds and improve health at the same time, but is glucomannan really all that it's cracked up to be?

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It’s technically a fiber supplement

The benefits of fiber are impressive—here’s a list—and glucomannan is a water-soluble fiber supplement that comes from the konjac root, which is native to Asia. “People in East Asia have used konjac fiber, also known as glucomannan powder, for thousands of years as both food and traditional medicine,” explains Josh Axe, DNM, CNS, DC, founder of DrAxe.com, author of Eat Dirt and co-founder of Ancient Nutrition.

It may help with weight loss

There are many supplements and foods that help you lose weight, and glucomannan is one of them. In fact, there is even a brand-name dietary supplement called Lipozene that boasts glucomannan as its primary ingredient. “Glucomannan weight loss just might be possible if you also lead a generally healthy lifestyle, but it’s important to choose the right product and take it in a safe manner,” Axe says. Konjac root’s fiber is very low calorie and very high in fiber. “Consuming konjac powder can help weight loss by promoting a feeling of fullness or satiety, which makes you less likely to overeat,” he says. “Of course, the rest of your diet has to be healthy, and you also need to be exercising regularly.”

It’s not a magic bullet

There’s little question that fiber can help you maintain or lose weight—here are 30 ways to get more fiber in your diet without even trying. But the research results on glucomannan are mixed. In one study, healthy overweight people were randomly assigned to ingest either a fiber supplement or a dummy pill while on a calorie-restricted diet. The fiber supplements were either glucomannan, glucomannan and guar gum (a common fibrous food additive), or glucomannan along with guar gum and alginate (another fibrous additive). After five weeks, all of the participants taking any form of glucomannan lost weight compared to their counterparts who were given a placebo. That said, a 2012 review of nine trials of glucomannan failed to show any statistically significant weight loss. “There really is no magical weight loss pill,” Axe says. “You need to follow a healthy lifestyle, including a whole foods-based diet and regular exercise, in order to have any additional element help you lose weight.”

It’s a natural prebiotic

Do you need a probiotic? Here’s how to know. Probiotics help restore the balance of good and bad bacteria in the gut. Prebiotics are precursors to probiotics, and konjac root powder is a prebiotic that feeds the friendly bacteria in the intestine. Glucomannan, like all prebiotics, passes through the upper part of the gastrointestinal tract and remains undigested because the human body can’t fully break it down,” Axe says. “But once prebiotics reach the colon, where they’re fermented by the gut microflora, they create probiotics.”

It relieves constipation

There are many reasons you’re constipated, and eating too little fiber is one of them.”Glucomannan is considered a bulk-forming natural laxative, which means that the intake of it is able to promote a larger, bulkier stool that more easily passes through the colon,” says Axe. Glucomannan and other bulk-forming laxatives typically encourage a bowel movement within 12 to 24 hours of intake, he says.

It lowers cholesterol

An analysis of 14 glucomannan studies in the American Journal of Clinical Nutrition showed that the weight loss supplement had beneficial effects on total cholesterol, low-density lipoprotein or “bad” cholesterol, dangerous blood fats called triglycerides, body weight and fasting blood sugar levels. However, it did not affect high-density lipoprotein or “good” cholesterol or blood pressure. “Being the fiber-centric substance it is, it’s able to decrease absorption of cholesterol in the gut by sponging up water in the digestive tract, which reduces the absorption of cholesterol by the body. You then have less cholesterol floating around in your blood,” Axe explains. There are other drug-free ways to lower your cholesterol.

It improves blood sugar control

Blood sugar is important—here are some ways to maintain healthy blood sugar levels—and glucomannan can help you control it. There are more than 20 scientific studies involving glucomannan and diabetes, Axe says. “One of the ways it can help diabetics is because it delays the stomach’s natural emptying process, which leads to more gradual sugar absorption and lower blood sugar levels after meals,” he says. But don’t overdo it if you have diabetes, he warns. “If you have diabetes and take glucomannan, you should monitor your blood sugar closely since it can lower blood sugar levels,” he says, “If you’re taking it along with a blood sugar-lowering drug, it may cause your blood sugar to go too low.” Make sure to discuss glucomannan with your diabetes doctor before trying it.

It’s tasteless

Since it’s pretty much tasteless, glucomannan powder can be added to smoothies and be used to make a high-fiber pasta, Axe says. Check out these super-food smoothies to jump start your mornings. When choosing a glucomannan powder or flour, make sure that it’s 100 percent pure with no additives or fillers. “Eating shirataki noodles or using glucomannan powder to make homemade noodles can be a great, safe way to incorporate glucomannan into your diet,” he says.

It’s safer as a powder

Glucomannan powder and capsules are likely safe for most healthy adults for up to four months, Axe says. Minor side effects can include diarrhea, flatulence, and bloating. “Solid tablets containing glucomannan can be unsafe for adults and are likely unsafe for children due to the fact that they can sometimes cause throat or intestinal blockages,” he says. There are some other vitamin mistakes you might be making.

It does pose some risks

Never take glucomannan products without water, Axe says. “It’s highly possible to choke if you try to swallow it dry,” Axe says. “If you have any medical condition or are taking medication already, consult a doctor before taking glucommanan.”

You can overdo it

The recommended dosage of glucomannan is lower than other fiber supplements because it expands so greatly in water, Axe says. “I highly recommend starting with one very small dose per day,” he says. Most powdered products suggest a half level teaspoon (two grams) daily with at least eight ounces of water 30 to 45 minutes before a meal. In general, when it comes to supplements, more is not always better.

There is a lot we don’t know

Supplement taker beware, warns Reshmi Srinath, MD, assistant professor of Diabetes, Endocrinology, and Bone Disease at the Icahn School of Medicine at Mount Sinai in New York City. “Supplements like glucomannan are not FDA regulated so we don’t know much about dosing or side effects,” she says. Check in with your doctor before taking glucomannan or any other supplements to help aid with weight loss. There are more secrets vitamin manufacturers don’t want you to know, too.

Denise Mann, MS
Denise is an award-winning health-science writer whose articles regularly appear in Reader's Digest, WebMD, healthday.com and cnn.com. Before freelancing, she worked for the Medical Tribune News Service for three years, and her articles were picked up by the Detroit Free Press, Chicago Sun-Times, Dallas Morning News and Los Angeles Daily News. She was also part of a writing team that won a 2008 Sigma Delta Chi award for a WebMD series on autism.