公衆衛生74巻6号

2010年06月発行

特集 肥満とやせ

肥満の健康影響

著者： 栗山進一¹

所属機関： ¹東北大学大学院医学系研究科公衆衛生学分野

ページ範囲：P.462 - P.468

はじめに

　肥満の健康影響を検討するのに疫学研究は不可欠である．疫学(Epidemiology)は，動物実験や培養細胞実験ではなく，実際の人口集団(population)を対象として，疾病とその規定因子との関連を明らかにする科学である．症状を訴えている患者さんに限らず，健康に暮らす人々を対象として，疾病予防に資する介入方法を明らかにする際には特に，その方法論を必要とする．

　疫学研究として最も信頼性の高いデザインは介入研究であるランダム化比較試験である．しかしながら，人を太らせてその影響を検討するという研究は倫理上許されない．したがって，観察研究のうち最も信頼性の高いコホート研究がベストエビデンスとなる．実際の人々の体型や生活を調査して，どのような体型，生活習慣の人が病気になりやすいのか，あるいはなりにくいのかを，長い年月をかけて追跡調査する．このような特定集団を追跡調査する方法を，コホート研究という．

　肥満の健康影響に関してはさまざまな疫学研究が行われデータが蓄積されてきた．本稿では特に日本人を対象としたコホート研究データに焦点を当ててレヴューし，日本人における肥満の健康影響に関するエビデンスを概説する．脳血管疾患と心筋梗塞は，がんと並んで日本の三大疾病と呼ばれる．また，日本人には2型糖尿病が多い．したがって，肥満が脳血管疾患や心筋梗塞，がん，糖尿病リスクに与える影響，ならびにどの体型の人が総合的に健康と言えるのかを表す指標としての総死亡率，医療費に与える影響を検討する．なお，本稿ではBody Mass Index(BMI)25以上30未満を過体重，30以上を肥満と呼ぶ．

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