The market is flooded with weight loss products, and konjac root is a Japanese root vegetable making its rounds as a weight-loss aid. While this root veggie may help you lose some weight, you may not lose as much as you hope. To avoid potential interactions, consult your doctor first before adding diet supplements such as konjac root to your routine.
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Konjac Root and Health
Konjac root is a source of soluble fiber called glucomannan, which is found in a number of weight-loss products and the substance that's supposed to help you drop pounds. It's not well understood how glucomannan works, but researchers theorize that it works by absorbing water in the stomach, forming a thick, viscous gel, which delays digestion to help keep you feeling full longer. It may also help prevent the absorption of carbohydrates, according to a 1988 study published in Gut.
Glucomannan also helps lower cholesterol levels and aids in blood sugar control, helping keeping it steady and preventing glucose spikes after eating. The gelling action of the fiber may be responsible for the effects on cholesterol and blood sugar, according to a study from 2000 published in Diabetes Care. The researchers report that the fiber in konjac root helped lower cholesterol better than fiber in oats or psyllium.
Evidence for Weight Loss
While it appears that konjac root may offer some assistance with weight loss, reports are inconsistent. Konjac glucomannan helped a small group of obese participants lose more weight and fat than a group taking a placebo, according to a 2015 study published in the Journal of the American College of Nutrition. However, a review study published in 2014 in the same journal reported conflicting results, noting that the weight-loss supplement didn't help people lose more weight than a placebo group.
Compliance taking the supplement may need to be taken into consideration when evaluating the results of these two apparently conflicting studies. The 2015 study reported significant weight loss once non-compliant participants were taken out of the results. But more research with accurate reporting from participants is still needed to determine if konjac root can reliably help with weight loss.
When taken as a diet supplement for a short amount of time, up to 16 weeks, konjac root appears to be safe, according to the Office of Dietary Supplements. However, side effects have been reported, including abdominal pain, diarrhea, gas and constipation.
If you have problems swallowing, for example, caused by esophageal strictures or narrowing, you may want to stay away from tablet forms of konjan, according to the ODS. The supplement may expand in your esophagus on its way down to your stomach and cause an obstruction. The same effects have not been observed in powdered konjac or capsule forms of the supplement, however.
Consider Low-Cal Konjac Root Food
As a supplement, it's not certain if konjac root is an effective weight-loss tool, but the Japanese root is used to make low-cal foods that might help you save calories on your weight-loss diet. Shirataki noodles, spaghetti-like noodles made from konjac root, are not only low in calories, but carbs too. One 4-ounce serving has 10 calories, 3 grams of carbs and 3 grams of fiber. Similar to tofu, shirataki noodles take on the flavor of what you mix them with, so toss these low-cal noodles with your favorite tomato sauce or use them to make a noodle stir-fry.
Konjac root is also used to make "rice," a calorie- and carb-free product, making it a good substitute for actual rice, which has 250 calories in a 1-cup cooked serving. Serve it as a side dish or use it to make a grain-based salad.
- Office of Dietary Supplements: Dietary Supplements for Weight Loss
- Journal of the American College of Nutrition: Konjac Glucomannan Dietary Supplementation Causes Significant Fat Loss in Compliant Overweight Adults
- Journal of the American College of Nutrition: The Efficacy of Glucomannan Supplementation in Overweight and Obesity: A Systematic Review and Meta-Analysis of Randomized Clinical Trials
- University of Michigan Health System: Glucomannan
- BMJ Open: Effect of Glucomannan Supplementation on Body Weight in Overweight and Obese Children: Protocol of a Randomised Controlled Trial
- Skinny Shirataki Noodles
- Diabetes Cares: Beneficial Effects of Viscous Dietary Fiber From Konjac-Mannan in Subjects With the Insulin Resistance Syndro m e
- The American Journal of Clinical Nutrition: Effect of Glucomannan on Plasma Lipid and Glucose Concentrations, Body Weight and Blood Pressure: Systematic Review and Meta-Analysis
- Gut: Glucomannan Prevents Post-Prandial Hypoglycemia in Patients With Previous Gastric Surgery
- U.S. Department of Agriculture: National Nutrient Database: Rice, Brown, Long-Grained Cooked