What is the korean term for people who eat a lot but don't gain weight?
In english, I guess you could say that someone has a fast metabolism if they eat a lot but don't / barely gain weight or just anyone who finds it hard to gain weight.

What is the korean word for people who find it hard to gain weight even if they eat a lot of food?

감사합니다 :)

Question

What is the korean term for people who eat a lot but don't gain weight?
In english, I guess you could say that someone has a fast metabolism if they eat a lot but don't / barely gain weight or just anyone who finds it hard to gain weight.

What is the korean word for people who find it hard to gain weight even if they eat a lot of food?

감사합니다 :)

Answer

we also use 'fast metabolism' term.
그 사람은 신진대사가 활발해서 살이 잘 찌지 않는다.

or by using basal metabolism,
그 사람은 기초대사량이 높아서 살이 잘 찌지 않는다.

Answer

We say, "그 사람은 살이 찌지 않는 체질이야."
It means the person has a body that is hard to gain weight.