Glucomannan is a water-soluble fiber from konjac root (Amorphophallus konjac) that absorbs 50x its weight in water — the highest water-holding capacity of any dietary fiber. It's the ONLY fiber supplement with an EU-approved health claim for weight loss ("contributes to weight loss in the context of an energy-restricted diet"). Our research shows a meta-analysis found modest but significant weight loss (0.8 kg over 5 weeks), plus clinically meaningful LDL reduction (16 mg/dL) and blood sugar improvement. The critical safety concern: glucomannan tablets/capsules can swell in the esophagus and cause obstruction — several countries banned tablet forms after choking deaths. ONLY take as powder mixed in liquid.
Glucomannan is a polysaccharide consisting of β-1,4-linked glucose and mannose units. When mixed with water, it forms an extremely viscous gel (50x volume expansion). This gel: (1) occupies stomach volume → increases satiety signals → reduces caloric intake at meals; (2) delays gastric emptying → slows glucose absorption → reduces postprandial glycemic spike; (3) binds bile acids in the intestine → increases fecal bile excretion → liver compensates by converting cholesterol to bile acids → LDL reduction; (4) serves as prebiotic fiber → fermented by gut bacteria to short-chain fatty acids (butyrate, propionate, acetate). The weight loss mechanism is primarily caloric displacement (eating less) rather than metabolic enhancement.
Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated:
Not medical advice. Based on published clinical research and systematic reviews.