which food source should provide 20 to 30 percent of the daily calories?

Protein also has 4 calories per gram. In a healthy diet, about 12 to 20 percent of your total daily calories should come from protein.

Your body needs protein for growth, maintenance, and energy. Protein can also be stored and is used mostly by your muscles. Your body changes about 60 percent of protein into glucose.

Protein takes 3 to 4 hours to affect blood sugar levels. When it does have an effect, foods that are mostly protein won't cause much of a rise in blood sugar.