"发胖"用英语可以表示为"gain weight"或"put on weight"。
"Gain weight"是"增加体重"的意思，来自动词"gain"，意思是"获得，增加"，加上名词"weight"，意思是"体重"，所以"gain weight"就是"增加体重"的意思。
"Put on weight"也是"增加体重"的意思，来自动词"put on"，意思是"穿上，戴上"，加上名词"weight"，意思是"体重"，所以"put on weight"就是"增加体重"的意思。
下面是一些使用"gain weight"和"put on weight"的英文例句及其中文翻译：
I've been eating too much junk food lately and have gained a lot of weight. (最近我吃了太多垃圾食品，体重增加了很多。)
I'm trying to put on weight because I'm too thin. (我在努力增加体重，因为我太瘦了。)
After having a baby, I put on a lot of weight that I couldn't lose. (生完宝宝后，我体重增加了很多，我没法减掉。)
I've been working out and eating healthy, but I still can't seem to gain weight. (我一直在锻炼身体，吃健康食品，但是我仍然不能增加体重。)
"Gain weight"是"增加体重"的意思，来自动词"gain"，意思是"获得，增加"，加上名词"weight"，意思是"体重"，所以"gain weight"就是"增加体重"的意思。
"Put on weight"也是"增加体重"的意思，来自动词"put on"，意思是"穿上，戴上"，加上名词"weight"，意思是"体重"，所以"put on weight"就是"增加体重"的意思。
下面是一些使用"gain weight"和"put on weight"的英文例句及其中文翻译：
I've been eating too much junk food lately and have gained a lot of weight. (最近我吃了太多垃圾食品，体重增加了很多。)
I'm trying to put on weight because I'm too thin. (我在努力增加体重，因为我太瘦了。)
After having a baby, I put on a lot of weight that I couldn't lose. (生完宝宝后，我体重增加了很多，我没法减掉。)
I've been working out and eating healthy, but I still can't seem to gain weight. (我一直在锻炼身体，吃健康食品，但是我仍然不能增加体重。)