It’s a general rule of thumb, straight from the dietitians: Eating foods in their whole state, rather than mashed, pureed, juiced, etc., generally, lessens the impact on blood sugar. For example, choose a baked potato over mashed, choose a whole apple over applesauce, and always choose the whole vegetable or the whole fruit rather than juicing it, so that you get all the beneficial fiber (which, don’t forget, cancels out some of those carbs) and the other nutrients stored in the skins and pulp.
An excellent illustration can be found in an orange. When you drink orange juice, you get the vitamin C but not the beneficial fiber and phytonutrients that come from the pulp. Even if you buy orange juice with pulp, you’re still not getting any of the fibrous white membrane, which is where the phytonutrients hide.
Nutrition science research is finding, increasingly, that it is not one substance or another that gives plant foods their disease-fighting power, but the interaction of these vitamins, antioxidants, and other plant chemicals. So, eat things the way Mother Nature presents them, and you won’t miss out on any hidden health benefits.