体重增加用英语可以说作 "gain weight" 或 "put on weight"。其来源可能源自英语中的动词 "gain" 和 "put on"，这两个动词均有 "增加、增多、获得" 的意思。

例句：

I need to start exercising because I've been gaining weight lately. 我需要开始锻炼，因为我最近体重增加了。

She put on a lot of weight after she had her baby. 她生完孩子后体重增加了很多。