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Add a few spoonfuls of plain yogurt to your morning smoothie. Yogurts, especially Greek yogurts, contain a lot of protein and can also help a smoothie develop a thick, creamy texture. Make sure not to get yogurts with added sugar, as these are generally not as healthy as plain yogurts. Almond butter, peanut butter, cashew butter, and other nut butters are rich sources that can add flavor to your morning smoothie. Go for organic, natural nut butters, free of unhealthy preservatives and additives, to add a healthy source of protein to your morning smoothie. Watch serving sizes, however. While nut butters are healthy, they contain a lot of calories. Make sure you only add a small amount of nut butter. Rice milk and hemp milk are not great sources of protein. Skim milk or soy milk can add a creamy taste to your smoothie while upping the protein content. Try mixing in a little soy or skim milk to your morning smoothie if you're trying to increase your protein intake.

Summary:
Add yogurt. Mix in natural nut butters. Add milk or soy milk.