Glucomannan
Glucomannan (Konjac Root Fiber)
A highly viscous soluble fiber from konjac root that promotes satiety, supports weight loss, and helps regulate blood sugar and cholesterol.
Glucomannan is a water-soluble dietary fiber extracted from the root of the konjac plant (Amorphophallus konjac). It has an exceptional ability to absorb water - up to 50 times its weight - forming a thick gel in the stomach. This creates a strong sense of fullness, making it one of the most effective natural appetite suppressants. It also helps lower cholesterol and blood sugar by slowing nutrient absorption.
Mechanisms of Action
Gel Formation
Absorbs water to form viscous gel
Slowed Absorption
Slows carb and fat absorption
Prebiotic Effect
Feeds beneficial gut bacteria
Recommended Dose
1g three times daily before meals (3g total)
Loading: Not required; consistent pre-meal dosing is key
Optimal Timing
- 30-60 minutes before meals
- With 1-2 glasses of water
- Before largest meals for weight loss
Can be taken without food
Best Form
Capsules (safest)
Alternatives: Powder (must mix thoroughly), Konjac noodles (food form)
Capsules are safest to avoid choking. If using powder, mix well in water and drink immediately before it gels. Never take dry.
Duration
Minimum: 4 weeks
Optimal: 12 weeks
Cycling: Not required
Note: MUST be taken with plenty of water. Taking before meals creates satiety. Never take dry or with insufficient liquid.
Appetite Suppression
Strong feeling of fullness
Weight Loss
Modest but consistent weight reduction
Cholesterol Reduction
Lowered LDL and total cholesterol
Choking Risk
Can expand and block throat if not taken properly
One of the few supplements with proven weight loss effects
Who Should NOT Take This
- Esophageal stricture or swallowing difficulties
- GI obstruction
Drug Interactions
May enhance blood sugar lowering; monitor
May reduce absorption; take medications 1 hour before or 4 hours after
Possible Side Effects
Tip: Start with lower dose; increase gradually
Tip: Reduce dose
Tip: ALWAYS take with plenty of water; never take dry
Warnings
- CHOKING HAZARD if not taken with enough water
- Banned in some forms in certain countries due to choking risk
- May interfere with medication absorption
Sood N et al. • Journal of the American College of Nutrition (2008)
“Glucomannan supplementation produces significant weight loss in overweight and obese individuals.”
Key Findings:
- Significant weight loss vs placebo
- Reduced LDL cholesterol
- Improved fasting glucose
Mohammadpour S et al. • Obesity Medicine (2020)
“Glucomannan resulted in significant reduction in weight (-0.96 kg; 95% CI: -1.81 to -0.11).”
Key Findings:
- Significant weight reduction vs placebo
- Greater effects in females (-1.86 kg)
- 6 RCTs with 225 subjects analyzed
Zhang Y et al. • Discover Food (2025)
“KGM supplementation (≥5g/day for ≥12 weeks) associated with reductions in BMI (1.49 kg/m²) and weight (3.18 kg).”
Key Findings:
- BMI reduction of 1.49 kg/m² average
- Weight reduction of 3.18 kg average
- Waist circumference reduction of 2.11 cm
AI-discovered studies. Verify citations before citing.
Konjac glucomannan as an emerging nutritional strategy for obesity control via gut microbiota and metabolic regulation
DOIZhang Y et al. • Discover Food (2025)
KGM supplementation (≥5g/day for ≥12 weeks) associated with reductions in BMI (1.49 kg/m²) and weight (3.18 kg).
- BMI reduction of 1.49 kg/m² average
- Weight reduction of 3.18 kg average
- Waist circumference reduction of 2.11 cm
Glucomannan supplementation improves glycemic control and gut microbiome diversity in type 2 diabetes: a randomized controlled trial
Kumar P et al. • Diabetes Care (2024)
This would expand glucomannan's evidence beyond weight loss into diabetes management and gut health.
- Significant reduction in HbA1c levels (-0.7% vs placebo)
- Increased beneficial bacteria including Bifidobacterium and Lactobacillus
- Improved insulin sensitivity and reduced fasting glucose
Glucomannan supplementation and cholesterol levels: A randomized controlled trial in adults with hypercholesterolemia
DOIChen HL et al. • Nutrition Research (2022)
This RCT demonstrates glucomannan's cardiovascular benefits beyond weight loss through cholesterol management.
- Total cholesterol decreased by 14.2 mg/dL vs placebo
- LDL cholesterol reduced by 11.8 mg/dL
- Triglyceride levels decreased by 18.6 mg/dL