We would not normally refer to a person's weight if they appear overweight. However, if you had to describe someone, to a police officer for instance after seeing a crime committed, then we might say they are heavy or quite weighty. Even here, the use of the word 'quite' would be my English way of trying to be polite! I might only say 'fat' if they were really large and the police would need to know that.

Hi there. So generally in English it’s best not to use a person’s weight to describe them at all; try your best to look for other things about them that stand out. Are they wearing glasses? Do they have red hair? Curly hair? Blonde hair? Maybe they are tall or wearing something that you can use to describe them instead. Is there something about their personality that stands out to you? If you really need to comment on a person’s weight, you could say something like “they are a little overweight” or “they are a bit bigger”. Using ‘a little’ or ‘a bit’ helps to soften the description a bit. I know it’s common in Chinese culture to comment on someone’s weight or appearance (“you have a pimple”, etc) to their face, but this can be quite hurtful and definitely would not go down well with someone who hasn’t been exposed to Chinese culture. (Even for those who have, it gets tiring and hurtful to hear something like this.) Unless you are very, very close to a person and they need help, or they have asked you for your advice, it’s generally not your place to comment on their weight at all. This was a good question to ask, learning a language is about more than just words and grammar. I’m sure that we English speakers commonly say things that aren’t very acceptable in Chinese culture too 😊 加油💪🏻