Glucomannan, a water-soluble dietary fiber derived from the root of the konjac plant (Amorphophallus konjac), has been studied for its potential to promote satiety and reduce appetite. The proposed mechanism is based on its high viscosity, which allows it to absorb water and expand in the stomach, thereby inducing a feeling of fullness and slowing gastric emptying. Several randomized controlled trials (RCTs) and meta-analyses have examined glucomannan’s effects on appetite and weight management. Some studies report modest reductions in hunger and caloric intake among participants taking glucomannan supplements compared to placebo. For example, a 2014 meta-analysis published in the Journal of the American College of Nutrition found that glucomannan supplementation led to statistically significant, though modest, reductions in body weight, likely related to decreased appetite and food intake. However, evidence is mixed, with some well-designed trials showing little or no effect on appetite or weight loss.

The European Food Safety Authority (EFSA) acknowledges that glucomannan can contribute to weight loss when consumed as part of a calorie-restricted diet, which indirectly supports its appetite-suppressing properties. Nevertheless, the overall quality of evidence is moderate, and effects tend to be small. Glucomannan is generally considered safe when taken as directed, though it may cause gastrointestinal side effects in some individuals. In summary, while there is scientific validation for glucomannan’s use in supporting appetite control, the strength of the evidence is moderate and further high-quality studies are needed to confirm its efficacy.