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to become thin; to lose weight; to slim
to become impoverished (of soil); to become sterile; to become infertile; to become barren
ダイエットで五キロ痩せました。
I lost 5 kg on a diet.
最近かなり痩せたんじゃない?
Haven't you lost weight recently?
痩せすぎは体に悪いですよ。
Being too thin is bad for your health.