PROBLEM TO BE SOLVED: To provide a fat synthesis inhibiting agent or a fat synthesis promoting agent comprising hydrogen nanobubble as an active ingredient, and a pharmaceutical composition or food and drink comprising any one of the agents.SOLUTION: This invention provides a visceral fat reducing agent or a fat synthesis inhibiting agent comprising hydrogen nanobubble water as an active ingredient, and a pharmaceutical composition or food and drink comprising any one of the agents.COPYRIGHT: (C)2015,JPO&INPIT【課題】水素ナノバブルを有効成分とする脂肪合成抑制剤又は脂肪合成促進剤、並びに、これらの剤のいずれかを含む、医薬組成物又は飲食物を提供すること。【解決手段】水素ナノバブル水を有効成分として含有する、内臓脂肪低減剤又は脂肪合成抑制剤、並びに、これらいずれかの剤を含む、医薬組成物又は飲食物。【選択図】なし