If your blender drink is replacing a meal, you want staying power. Sure, adding some type of milk is going to offer calcium and some protein, but the usual four-ounce pour might get you about four grams, which isn't much. Adding Greek yogurt is a good idea or a scoop of sugar-free protein powder.
Some type of juice is going to sweeten things up, but juice is high in sugar calories. So keep fruit or juice to one cup, which will average around 100 calories. Remember, low-sugar fruits, like berries, are a better option than calorie pricey pineapple.
Now try adding greens. A leaf of kale or spinach leaves won't alter the taste profile much, but will give you a low-cal boost of nutrients, like vitamin C and folate, for a mere 30 calories.
Making a smoothie filling means adding extras with fiber. Chia seeds, rolled oats, even chopped almonds will thicken up your concoction and stay with you awhile. A tablespoon of chia is about 60 calories, two tablespoons of oats is 35, and 10 almonds will cost you 70 calories.
Don't forget spices to heighten taste. Cinnamon is a good choice, and even cocoa powder helps. Sliced ginger is a sassy addition that will keep your stomach feeling happy. A teaspoon of most adds a mere 5 to 10 calories.
But watch out for goodies like chocolate and peanut butter. They're very tasty, but a little bit of either can easily tack both fat and calories.
Remember, if your smoothie is just a snack, you want it to be around 200 calories and if it's a meal, then 500 calories. So you should aim for something that is around 12 to 16 ounces.