Smoothies can be convenient, delicious, and nutritious, but certain ingredient combinations can spike your blood sugar. Here’s how to build a smoothie to avoid a blood sugar spike.
While many fruits provide fiber, vitamins, and antioxidants, some tend to raise blood sugar more quickly than others. Fruits that are lower on the glycemic index generally take longer to digest and lead to a slower, more gradual rise in blood sugar. Choosing these types of fruits more often can help create a balanced smoothie, particularly when combined with protein, fiber, and healthy fats.
Lower-glycemic fruits to add to smoothies include:
- Berries, such as strawberries, blackberries, blueberries, or raspberries
- Kiwi
- Apples
- Cherries
Fruits that are higher on the glycemic index, like ripe bananas or pineapple, can still fit into a smoothie, but they’re best used sparingly.
When making a smoothie, it’s surprisingly easy to toss in more fruit than you’d normally eat whole. Generous portions can quickly raise the total sugar content, even if you’re choosing low-glycemic index fruits.
The American Diabetes Association suggests limiting fruit to about half a cup or one small piece per meal or snack. In a smoothie, that could mean using half a cup of berries or combining smaller amounts of two fruits while keeping the total fruit portion to about a single serving.
Adding protein to a smoothie helps slow how quickly sugar enters your bloodstream. When a smoothie contains mostly carbohydrates from fruit, blood sugar can rise quickly. Protein takes longer to digest, which helps balance that response. And because protein also helps make a smoothie more filling, it can reduce the urge to snack soon after.
Examples of protein to add to a smoothie include:
- Plain Greek yogurt or skyr
- Unsweetened protein powder
- Unsweetened nut butters
- Tofu
Even when you include fruit and protein, a smoothie that’s low in fiber may still be digested too quickly. Fiber slows down digestion, which helps delay how quickly sugar is absorbed and prevents sharp spikes.
Adding fiber-rich ingredients also helps you feel satisfied longer. This is helpful in smoothies, where you can end up consuming more calories than you realize.
High-fiber ingredients that might work well include:
- Chia seeds
- Ground flaxseed
- Rolled oats
- Psyllium husk
Healthy fats help round out a smoothie and make it feel more satisfying without adding unnecessary calories. They help slow digestion just enough so that the natural sugars in fruit enter your bloodstream gradually.
Avocado is a popular smoothie add-in for good reason. It adds creaminess along with healthy fats and fiber, and research has linked avocado intake to better glucose control, especially in people with type 2 diabetes. Most of its fat comes from heart‑healthy monounsaturated fats, and its carbohydrates are largely fiber.
Nuts and seeds fit well here, too. In addition to protein and fiber, they’re known for their healthy fat content, which can help achieve a well-balanced smoothie.
Healthy fats to add to a smoothie include:
- Avocado
- Unsweetened nut butter, such as almond, peanut, or cashew
- Walnuts or cashews
- Hemp seeds
Using a sugary liquid, like fruit juice, as a smoothie base is a common mistake that can quickly undo the benefits of your other healthy ingredients. Juicing removes much of the fiber, leaving concentrated sugar water that the body absorbs almost instantly, resulting in a sharp glucose spike. Other bases, like sweetened plant milks, honey, or flavored syrups, can also add sugar without much fiber or protein to balance it.
Instead, reach for unsweetened liquids as your base. Water is one of the best options, especially when your smoothie already includes fruit, protein, and other flavorful add-ins.
Liquid bases to use include:
- Plain water
- Unsweetened coconut water
- Unsweetened almond milk or other plant-based milk
- Unsweetened dairy milk
Vegetables are a good way to boost the nutrition of a smoothie without adding extra sugar. They add volume and provide vitamins, minerals, and fiber.
Mild‑tasting vegetables work well because their flavor isn’t overpowering, and they’re a convenient way to sneak in a serving of vegetables.
Vegetables that blend well in smoothies include:
- Spinach or kale
- Zucchini
- Cucumber
- Cauliflower
You don’t need a complicated recipe to make a smoothie that’s easier on your blood sugar. Understanding the role each ingredient type plays can help you create blood-sugar-friendly smoothie combinations that are balanced, satisfying, and taste great.
If you want a place to start, try this simple recipe:
- Half-cup frozen berries
- Half of a small just-ripe banana
- Half-cup plain Greek yogurt
- 1 tablespoon chia or ground flaxseed
- Half of a medium avocado
- 1 cup unsweetened almond milk or water
- 1 cup spinach
- Ice as needed
Add all ingredients to a blender, and blend until smooth. If the smoothie is too thick, add a splash more liquid. If it’s too thin, toss in a few extra ice cubes until it reaches the texture you like.
This recipe is flexible and easy to adjust based on what you have on hand.
