In Korean, ‘you ate heat’ means you feel sick or are ill because of the hot weather during summer days. Even though you are not physically sick but are being drained of energy because of the heat, and eventually cause you a lack of motivation and or appetite.
But this expression is not used with 추위(coldness).
오늘 진짜 덥다. It is really hot today.
그치? 너무 더워서 더위 먹을 것 같아. Right? It is so hot that I will get sick.
정말. 우리 시원한 거라도 사 먹자. Yeah. Let’s go and eat something cold.