Low-Sugar, High-Protein Lemon Raspberry Muffins. Berries are finally in season! Pick up a pint, and make these moist and naturally sweet muffins. Made with Greek yogurt instead of buttermilk, they're a tasty way to get some protein without all the fat. These are so light and summery, with bursts of juicy raspberries — perfect to grab with your morning smoothie or to bake up for a weekend brunch.