Konjac glucomannan molecular and rheological properties that delay gastric emptying and improve the regulation of appetite

A safe and cost effective approach to reduce obesity and accompanying chronic disease would be through controlling appetite and energy balance. Konjac glucomannan (KGM), a soluble dietary fiber (DF) that hydrates gradually and develops high viscosity in solution, has been demonstrated in some preclinical and clinical studies to reduce appetite and obesity. KGM has the highest hydrated volume at the lowest concentration of any DF. Therefore, oral KGM can instill a filling of fullness at a lower dose than other fiber supplements. Appetite reduction may be through increasing gastric retention and delaying gastric emptying by the “mass effect” of a gel-like viscous mass forming in the stomach that triggers afferent vagal signals of fullness. Absorption of nutrients in the lumen is slowed and beneficially increases the levels of appetite related hormones. The intake of KGM either as a supplement or in foods has been shown to have a weight loss effect. However, the results of randomized clinical trials have not been consistent. Besides differences in dose, study duration, and participant selection, the molecular structure and hydration properties of KGM are not described. This may be part of the explanation for the inconsistent results. The current review collected published information related to the role of KGM supplementation in regulation of appetite and obesity, focused on the association between micro and macro physicochemical structures of KGMs with their functions as appetite regulator. Collective clinical data of KGM on long-term metabolic energy surplus and weight loss were also provided.