The results reported are not surprising in the least. When one is fasting, their blood sugar drops, making them hungry. Unconsciously– and perhaps consciously– we know that starches (carbs) quickly raise our blood sugar. The more refined the carb, the more devoid of fiber (which slows absorption and slows the rise of blood sugar), the faster it is absorbed. Rice cakes are absorbed faster than pure sugar, for example. So, we know what we need to get the blood sugar up quickly.
Fats and proteins are absorbed more slowly and have a lower impact on blood sugar.