My pineapple energy smoothie is what I blend when the afternoon slump hits. Frozen pineapple brings natural carbs for quick fuel, grapefruit adds a bright wake-up zing, and spinach rounds it out in a light 143-calorie glass.
Pour the water into a blender. Add the spinach and grapefruit and blend on high until smooth.
Add the pineapple and protein powder, if using. Blend on high until smooth, 45 to 60 seconds, adding a splash more liquid if it's too thick. Pour into a glass and serve immediately.
Notes
Greens Tip: Fresh or frozen spinach or kale both work. If you're new to greens, start with less and work up.
Sweetness: For a sweeter smoothie, add a ripe banana or a splash of orange juice.
Citrus Swap: Grapefruit can be tart, so use an orange instead for a milder flavor.
Make Ahead: Prep the spinach, grapefruit and pineapple in freezer smoothie packs, then blend with water when you're ready.