1To gain weight; to become fat or plump (usually due to overeating or lack of exercise).
最近忙しくて運動不足だから太ってきた。
I've been busy and lacking exercise lately, so I've been gaining weight.
冬はつい食べ過ぎて太る人が多い。
Many people tend to gain weight in winter because they eat too much.
医者にコレステロールを下げるために太らないようにと言われた。
The doctor told me not to gain weight to lower my cholesterol.