The object is to provide a food-derived effective ingredient which can promote the reduction in accumulated fats or the like. Disclosed is a body fat reduction-promoting agent, a leptin production-promoting agent, an anorexigenic agent, a PAI-1 production-suppressing agent or an anti-thrombotic agent, each comprising an extract from a chestnut astringent skin as an active ingredient. The extract from a chestnut astringent skin, which is a natural component, can be used as an extremely safe body fat reduction-promoting agent, leptin production-promoting agent, anorexigenic agent, PAI-1 production-suppressing agent or anti-thrombotic agent. Particularly, the body fat reduction-promoting agent can reduce an accumulated visceral fat and therefore can directly prevent obesity.