YOU SAID:

if ain't fat i don't want that

INTO JAPANESE

太っていないならそれは望まない

BACK INTO ENGLISH

you don't want it if you're not fat

INTO JAPANESE

太っていなければ要らない

BACK INTO ENGLISH

you don't need to be fat

INTO JAPANESE

太る必要はありません

BACK INTO ENGLISH

don't need to be fat

INTO JAPANESE

太る必要はない

BACK INTO ENGLISH

no need to gain weight

INTO JAPANESE

体重を増やす必要はありません

BACK INTO ENGLISH

no need to gain weight