Her face had already lost its puppy-fat.

她的脸已经不再肉嘟嘟的了。

After Jane lost her puppy-fat she became very slim.

简发育期间出现的肥胖消除之后，显得十分苗条。

This will get rid of that puppy fat: but this pooch doesn't seem too keen on keeping fit.

这能帮小狗减肥，但这个小家伙好像不怎么热衷于健身。