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Konjac Glucomannan is a soluble, fermentable, polysaccharide produced from the Amorphophallus Konjac (elephant yam or konjac plant) found in Asia. Konjac is available as supplements, in drink mixes, additive (emulsifier and thickener) to food products such as flour and pasta.
FG 5 PR - Konjac Effects On Weight Reduction, Cravings And Diabetes in GLOBESITY Bootcamp for the Obese

Table of Contents

Authors: Marcus Free MD, Rouzbeh Motiei-Langroudi MD, Waqar Ahmad PhD, Kelly Daly RDN, and Don Juravin (Don Karl Juravin).

Abstract (Research Summary)

  • Konjac promotes healthy gut flora by increasing the population of Bifidobacteria colonies (1.26 Prebiotic Index) and enhancing production of butyric acid (8.24 mM concentration) (Ariestanti et al., 2019).
  • Konjac (3 g daily) promotes reduction in weight by 2.87 lbs; percentage body fat by 0.83%; fat mass by 2.49 lbs; total cholesterol by 13.9 mg/dL, and low-density lipoprotein (LDL) cholesterol by 13.7 mg/dL in 83 individuals (compliant vs. non-compliant) over 2 months (Kaats, 2015).
  • Konjac reduces cravings by improving insulin and leptin sensitivity and reducing resistin and the unhealthy gut flora (Segal, 1996; Islam, 2012).
  • Konjac causes weight loss of up to 6.6 lbs (3 kg) per month, or up to 79 lbs (36 kg) per year, when used before meals (Birketvedt, 2005).
  • Konjac decreases blood sugar levels by 3.8% to 6.6% as a result of slowing glucose metabolism and increasing insulin sensitivity (Vuksan, 2000; McCarty, 2002).
  • Konjac slows glucose metabolism by up to 50% resulting in reduced cravings for sugary foods that are associated with hypoglycemia (McCarty, 2002).
  • Konjac is a highly viscous, water-soluble dietary fiber obtained by grinding the tuber root of the Amorphophallus Konjac plant (Kishida, 1978).


Konjac Glucomannan is a soluble, fermentable, polysaccharide produced from the Amorphophallus Konjac (elephant yam or konjac plant) found in Asia. Konjac is available as supplements, in drink mixes, additive (emulsifier and thickener) to food products such as flour and pasta.

Konjac absorbs water in the gastrointestinal tract to form a fiber, reducing the absorption of carbohydrates and cholesterol and thus supporting weight loss up to 2.87 lbs. Konjac (2-4 g daily) also improves satiety and fat loss by improving blood sugar to 6.3%. Konjac improves insulin sensitivity, resulting in better appetite control and fewer blood sugar spikes or cravings. Konjac promotes healthy bacterial flora by increasing Bifidobacteria and Lactobacilli, which in turn decreases fecal pH and promotes colonic fermentation. 

Konjac Effects on Weight Reduction

Konjac (1.24 g to 3 g daily) decreases weight by up to 79 lbs (36 kg) per year. The high viscosity of Konjac increases gastric transit time and satiety and restricts the absorption of glucose and fats from the gut.

  • Konjac promotes healthy gut flora by increasing the population of Bifidobacteria (1.25 Prebiotic Index), which in turn lowers blood cholesterol (Ariestanti et al., 2019). 
  • Konjac (3 g daily) promotes reduction in weight by 2.87 lbs; percentage body fat by 0.83%; fat mass by 2.49 lbs; total cholesterol by 13.9 mg/dL, and low-density lipoprotein (LDL) cholesterol by 13.7 mg/dL in 83 individuals (compliant vs. non-compliant) over 2 months (Kaats, 2015).
  • Konjac reduces weight by up to 6.6 lbs (3 kg) per month, or up to 79 lbs (36 kg) per year when used before meals (Birketvedt, 2005). Konjac also promotes satiety (Burton-Freeman, 2000).
  • Konjac (1.24 g to 3 g daily in divided doses for 5 to 8 weeks) improves weight loss (Birketvedt, 2005, Walsh, 1984).
  • Konjac and Xanthan work synergistically to decrease appetite and increase satiety, therefore making their combined weight loss effect much stronger than working by themselves (Paquet 2014, Challen 1994).
  • Konjac slows the rate of gastric emptying and glucose diffusion in the small intestine. This reduces glucose absorption postprandially and may reduce adiposity (Islam, 2012).
  • Konjac increases satiety by slowing the rate of gastric emptying. Longer satiety reduces consumption of unnecessary caloric intake (Keithley, 2005).
  • Konjac has been shown to slow carbohydrate absorption (McCarty, 2005).

Konjac Effects on Cravings

Konjac decreases cravings by slowing glucose metabolism (by up to 50%), normalizing blood glucose levels, improving leptin sensitivity and improving the ratio of healthy gut flora.

  • Konjac increases healthy gut flora by enhancing the production of butyric acid (short-chain fatty acids) by 8.24 mM concentration. This improves insulin sensitivity and reduces cravings (Ariestanti et al., 2019).
  • Konjac slows glucose metabolism by up to 50% and normalizes blood glucose levels, resulting in reduced cravings for sugary foods (McCarty, 2002).
  • Konjac improves postprandial leptin sensitivity and reduces leptin plasma concentrations (Islam, 2012). This results in improved insulin sensitivity and reduced cravings in obese and glucose-intolerant individuals (Segal, 1996).
  • Konjac significantly increases healthy gut flora ratio and species, such as Bifidobacteria, providing a strong defense against cravings that are caused by the unhealthy gut flora (Chen, 2005; Segal, 1996).
  • Konjac increases satiety by slowing the rate of gastric emptying. This inhibits the imbalance of hormones which cause cravings, such as ghrelin and neuropeptide Y (Burton-Freeman, 2000; Keithley, 2005; Paquet, 2014).

Konjac Effects on Diabetes

Konjac slows glucose metabolism by 50%. It improves insulin sensitivity and decreases postprandial blood glucose levels by 3.8% to 6.3%. Konjac also helps diabetics by decreasing glucose absorption from the gut due to its high viscosity.

  • Konjac slows glucose metabolism and lowers insulin response by 50% (McCarty, 2002).
  • Konjac improves postprandial leptin sensitivity and reduces resistin plasma concentrations resulting in better glucose control and fat reduction (Islam, 2012).
  • Konjac reduces glucose by 5.7% when taken daily for three weeks (Vuksan, 1999).
  • Konjac decreases blood sugar by 3.8% to 6.3% when taken for 8 weeks (Vuksan 2000).
  • Konjac increases insulin sensitivity (Vuksan, 2001).
  • Konjac lowers fasting and postprandial blood glucose by 50% (Osilesi, 1985; McCarty, 2002).
  • Konjac is differentiated from other soluble fibers by its extraordinarily high viscosity (Vuksan, 2001; Kishida, 1978). High viscosity dietary fibers reduce the fat absorption from the intestine promoting fat loss (Gallaher, 2000). Viscous fibers in meals reduce appetite and carbohydrate absorption, therefore decreasing the levels of serum glucose and resulting in weight loss (Burton-Freeman, 2000; Saper, 2004).
  • Konjac was found to act as an inhibitor of ghrelin signaling and thus appetite in individuals with type 2 diabetes (Scalfi, 1987).

Benefits, Side Effects, Interactions


  • Konjac is consumed orally for constipation, weight loss in adults and children, type 2 diabetes (Chen, 2003) and reducing serum cholesterol (Via 1992, Walsh, 1984). Konjac is also used in food preparation.
  • Konjac may inhibit dermatitis (Onishi, 2005).
  • Konjac reduces hepatic injury caused by oxidative stress (Kishida, 1978).


Konjac is Generally Recognized As Safe (GRAS) according to the FDA.

Side Effects

  • Flatulence and bloating: Konjac may increase intestinal and gut gas production resulting in mild flatulence and bloating.
  • Diarrhea: Excessive intake of Konjac may result in mild diarrhea.
  • Hepatitis: Acute cholestatic hepatitis has been reported with the use of Konjac (Villaverde, 2004).
  • Respiratory sensitization and bronchial asthma (Bernstein, 2007; Shichijo, 1969) 
  • Ocular injury (Kneepkens, 1988)

Drug Interactions

  • All medications taken orally: Konjac may decrease the absorption of other medications taken orally, thus decreasing their effectiveness. To avoid this interaction, take Konjac 1 hour before or 4 hours after any other oral medication.
  • Antidiabetic drugs: As both Konjac and antidiabetic drugs (like glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), etc.) decrease blood glucose levels, it is important to monitor glucose levels and speak to a physician about decreasing the antidiabetic drug if required.

Interactions With Herbs & Supplements

  • Herbs and supplements that decrease blood glucose: Konjac has hypoglycemic effects and concomitant use with other herbs and supplements that decrease blood glucose levels (like bitter melon, cowhage, ginger, goat’s rue, fenugreek, kudzu, willow bark, etc.) might increase the risk of hypoglycemia.
  • Vitamins A, D, E and K: Konjac may reduce absorption of all fat soluble vitamins, possibly because it increases excretion of bile acids (Doi, 1983).

Interactions With Foods

  • None known.


  • Pregnancy and breastfeeding: There is limited research and therefore best to avoid during pregnancy or breastfeeding.
  • Diabetes: As Konjac lowers blood glucose levels, it is important to monitor glucose levels to avoid hypoglycemic episodes. Diabetics are advised to consult a physician before consuming.
  • Patients with difficulty swallowing should avoid consuming Konjac tablets and capsules.
  • Konjac should not be used if suffering from diarrhea (Keithley, 2005).
  • Surgery: Konjac affects blood glucose levels and might interfere with blood glucose control during and after surgical procedures. Patients should discontinue Konjac at least 2 weeks before elective surgical procedures.


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This research was sponsored by GLOBESITY FOUNDATION (nonprofit organization) and managed by Don Juravin. GLOBESITY Bootcamp for the obese is part of GLOBESITY FOUNDATION which helps obese with 70 to 400 lbs excess fat to adopt a healthy lifestyle and thereby achieve a healthy weight.

Tags: konjac, weight reduction, GLOBESITY FOUNDATION, weight loss, cravings, diabetes, healthy weight

DOI: 10.5281/zenodo.3971117


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