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Medically reviewed by Aviv Joshua, MS, RDN
Key Takeaways
- Bananas raise blood sugar, but the amount depends on size and ripeness.
- Green or less-ripe bananas cause smaller spikes than very ripe ones.
- Refrigerating bananas slows ripening and reduces sugar spikes. Smaller portions and pairing bananas with protein or fiber can also help stabilize blood sugar levels.
Bananas are a nutritious fruit that is also rich in potassium. Although bananas do cause blood sugar to rise, they can still be part of your diet without causing major spikes if you watch ripeness, portion size, and what you pair them with.
Do Bananas Raise Blood Sugar?
The glycemic index (GI) measures how quickly a food raises blood sugar. Low-GI foods release glucose slowly, while high-GI foods can trigger rapid spikes.
A medium-sized ripe banana has a GI of about 51, which is considered low. The glycemic load (GL) accounts for both GI and portion size. A typical serving of banana has a GL of 13, making it a medium-GL food.
Bananas contain natural sugars, which are carbohydrates that are digested and absorbed into the bloodstream, thereby raising blood sugar levels. How much your blood glucose increases depends on factors such as the size and ripeness of a banana.
Refrigerating bananas slows ripening by preserving starch and delaying its conversion to sugar. Keeping bananas cold helps keep GI low, reducing the likelihood of sharp blood sugar spikes.
How Banana Ripeness Affects Blood Sugar Rise
Less-ripe bananas keep blood sugar steadier; very ripe ones spike it faster. As a banana ripens, starch turns into sugar, raising its GI, which causes faster blood sugar spikes.
| Banana Ripeness and GI | ||
|---|---|---|
| Ripeness | GI | What It Means |
| Green (unripe) | 30-40 | Lowest rise in blood sugar |
| Yellow with green tips (slightly under-ripened) | 40-50 | Mild rise |
| Entirely yellow (ripe) | 50-60 | Moderate rise |
| Yellow with brown spots (slightly overripe) | 60-65 | Faster rise |
| Mostly black (overripe) | 65-70 | Highest rise |
Tips for Eating Bananas Without Spiking Blood Sugar
The American Diabetes Association says that for most people, including those with diabetes, bananas can be incorporated into a balanced diet. The key to enjoying bananas without triggering a blood sugar rush is to use three simple strategies:
- Choose green or less-ripe bananas: Higher resistant starch (a carbohydrate that resists digestion in the small intestine) in greener bananas slows digestion, keeps GI lower, and minimizes blood sugar spikes.
- Watch portion size: Even low-GI fruits can elevate blood sugar if eaten in large quantities. Stick to smaller bananas or split a bigger one into two portions and eat them intermittently throughout the day.
- Pair with protein, fiber, or healthy fats: Pairing bananas with protein, fiber, or healthy fats (unsaturated fats) can offset a rise in blood sugar. Try eating a banana with a handful of nuts, blending it into a smoothie with yogurt, or slicing it onto some overnight oats.
- Keep bananas cool: Storing your bananas in the refrigerator can slow ripening and keep GI low.
Are Bananas Good for Exercise?
Bananas are often eaten before, during, or after workouts because their carbohydrates provide a quick source of energy. Additionally, electrolytes like potassium support healthy muscle function. While further research is needed to confirm whether bananas prevent muscle cramps, they remain a popular food choice among athletes.
When to Speak With a Healthcare Provider
If you notice frequent blood sugar spikes after eating bananas (or any fruit), talk to a healthcare provider. Tracking your response with a glucometer or continuous glucose monitor can give real-time feedback.
If needed, a registered dietitian can also help create meal plans tailored to your personal glucose profile.
Read the original article on Verywell Health
