When you eat, your body is looking for nutrients – vitamins, minerals, carbohydrates, protein, fat, etc. Whole foods provide a unique balance of each of these nutrients, and every food has a different balance.
Examples of whole foods are brown rice, whole grain flour, sunflower seeds, or an apple. Examples of foods that are not whole are white rice, white flour, refined sunflower oil, or apple juice.
If you eat foods that are not whole – that have had some part of them like vitamins or fiber removed – your body will be missing the nutrients from that part of the food and will try to tell you to go get it.