Watashi no Onaka no Sekinin Totte!

Ritsu, who has gotten somewhat chubby from eating her roommate Ruka's cooking, becomes determined to get down to lost 7.5kg in three months. When Ritsu's attempt at a salad-only diet proves destructive, Ruka sets her on a new diet that allows her to eat delicious meals that are under 400kcal each.

(Source: Mangadex)