Prebiotic Effects of Insoluble Konjac Glucomannan Derived from Edible “Konnyaku” on Weight Control

Obesity is a major global health issue, and novel dietary approaches are needed for prevention and management. This study investigates the effect of insoluble konjac glucomannan (iKGM) derived from edible konnyaku, a traditional Japanese food, on weight gain suppression in mice. Mice treated with iKGM showed increased fecal volume, reduced food intake, and suppressed weight gain (Day 21; <i>p</i> < 0.01). This weight-suppression effect was prebiotic rather than physical properties of iKGM, as antibiotic treatment abolished the weight-suppressing effect despite increased fecal volume. iKGM treatment altered the gut microbiota, notably increasing <i>Akkermansia muciniphila</i> (Day 21; <i>p</i> < 0.01), a bacterium associated with weight loss, along with elevated levels of short-chain fatty acids (SCFAs) such as butyrate and propionate (Day 21; <i>p</i> < 0.01). Furthermore, iKGM-induced weight suppression was linked to elevated leptin levels (Day 21; <i>p</i> < 0.01), an appetite suppressant induced by SCFAs. These results suggest that iKGM modulates gut microbiota, increases <i>A. muciniphila</i>, induces leptin production, and reduces food intake, inhibiting weight gain. This study indicates that iKGM may represent a promising approach for obesity prevention through gut microbiota modulation. Future research should investigate the mechanisms of iKGM's effects on microbiota and explore its long-term safety and efficacy in clinical trials.