BMI of Japanese women drops from teens to 20s; unique trend poses health risks

Here is an interesting article from a Japanese newspaper.
Yeah, let them worry about LOSING TOO MUCH WEIGHT! lol

下に日本語記事も掲載しています。日本ってとにかく痩せてる人ばかりですよねぇ。帰国するのが怖いです。

BMI of Japanese women drops from teens to 20s; unique trend poses health risks

A research team has found a downward shift in Body Mass Index (BMI) among Japanese women from their late teens to their 20s, a trend unseen in other countries.

"There's a good image attached to being slim, but in fact, there are indications that it can have negative effects on health and childbearing," the University of Tsukuba endocrinology and metabolism department research team says.

In general, BMI -- a measurement of one's body fat calculated by height and weight -- begins to increase around age six. According to data from Japan's national health and nutrition survey and similar surveys conducted in the U.S. and South Korea, the BMIs of American men and women as well as Korean and Japanese men continued to increase from age 10 onwards. Among Korean women, BMIs stopped rising around age 18, and remained unchanged through their twenties. Among Japanese women, however, BMIs stopped climbing around age 15, and began decreasing in their twenties.

An analysis of Japanese women's BMIs after 1958 has shown that in the 1970s, when women born between 1950 and 1959 were in their late teens or early twenties, their BMIs suddenly began to drop.

Low body weight in young women can often lead to eating disorders, propensity for depression, and loss of bone density. Such women are also at high risk of giving birth to babies with low birth weight.

"Our society has a strong tendency to encourage people to lose weight, but low body weight among young women is a serious problem," says Hirohito Sone, a professor at Tsukuba. "We'd like to look into why the desire to be slim escalated from around 1970."

The research team's findings will be published in an American epidemiology journal in May.

(Mainichi Japan) April 12, 2009

女性の肥満度：ＢＭＩ、日本だけ「減少」　やせ願望？専門家、悪影響を指摘
　◇１０代後半から２０代にかけ　日本人女性の肥満度を示す体格指数（ＢＭＩ）が、１０代後半から２０代にかけて減少に転じ、他国では見られない特有の傾向であることが、菅原歩美・筑波大研究員（内分泌代謝科）らのチームの研究で分かった。米疫学誌の５月号に発表する。菅原さんは「やせていることのイメージは良いが、実際は健康や出産への悪影響が指摘されている」と話す。

　一般に、ＢＭＩは６歳ごろから増加する。日本の国民健康・栄養調査と、同様の調査を持つ米国、韓国のデータを調べたところ、米国男女と韓国、日本の男性は、１０歳以降はＢＭＩが増え続け、韓国女性は１８歳ごろ増加が止まり、２０代は横ばいだった。一方、日本女性は、１５歳ごろ増加が止まり、２０代は年齢とともに減少した。

　また、５８年以降の日本女性のＢＭＩを解析した結果、５０～５９年生まれの女性が１０代後半から２０代前半だった７０年ごろ、一斉にＢＭＩが減り始めた。

　若い女性のやせは、摂食障害やうつ傾向、骨密度の低下を起こしやすく、出産時に低出生体重児になる確率が高い。曽根博仁・同大教授は「やせることを勧める風潮が強いが、若い女性のやせは深刻だ。７０年ごろを境にやせ願望が強まった背景を探りたい」と話す。【永山悦子】

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　■ことば

　◇ＢＭＩ（体格指数）
　国際的に肥満度を示す指標として使われ、体重（キロ）÷身長（メートル）の２乗で算出。日本肥満学会は１８．５未満をやせ、２２を標準、２５以上を肥満とする。毎日新聞　2009年4月7日　東京夕刊

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