Apples are considered a nutritious food; so this expression is intended as advice. To stay healthy (and to not have to visit the doctor) you should eat healthy food like, an apple, every day.

苹果富含营养，所以这种表达代表一种建议。要保持健康(不用看医生)你应该每天吃苹果这样的健康食物。

youdao

I'd like to stay healthy, but to be honest, I only eat food that tastes good.

我想保持健康，但老实说，我只吃那些吃起来好吃的食物。

youdao

I prefer to only eat food that I like, but isn't it important to eat food that's healthy, even if you don't like it?

我更喜欢只吃我喜欢的食物，但是难道吃健康的食物，尽管是你不喜欢的食物，不是很重要吗？

youdao

Even if they're given healthy food at the same time, they'll tend to ignore the healthy food and eat a diet like this.

即使同时给它们喂食健康食品,它们也会选择前者的食物,而不吃健康食品

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选