There are two main reasons why milk can't be eaten with bananas at the same time: First, bananas are cool, milk is hot, and eating cold food and hot food at the same time will easily lead to spleen and stomach disharmony, which will lead to diarrhea; Secondly, from the analysis of their components, the fruit acid in bananas will denature and precipitate protein in milk, making it difficult to digest and absorb, thus leading to diarrhea.