If you ate the same food day after day after day, you'd have too many of some nutrients and too little of others, and you become nutritionally deficient.

如果你日复一日的只吃一种食物,某类营养就会过剩,而另一些则会不足,你就会营养不良

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

First, let's talk about malnutrition. Now usually that concept gets used to talk about too little nutrition, but in fact, if you consider mal to mean poor rather than too little, and poor nutrition can really get manifested as under-nutrition, over-nutrition, or just unhealthy eating in general.

我们首先谈谈营养不良,现在我们通常把这个概念视同于缺乏营养,但实际上理解为"不好的",比"不足"更为恰当,一般而言,不好的营养可以被理解为,营养不足,营养过剩,或者仅仅是指不健康的饮食

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选