Using a continuous glucose monitor from Levels, I tested my blood sugar after eating five popular fruits: a banana, strawberries, grapes, an apple, and an orange. How do you think they will match up? I share my results in this blog post.
Best and Worst Fruit – At-A-Glance
- Fruits vary in sugar, carbohydrate, and fiber content, making some fruits better for stabilizing blood sugar levels.
- I tested five fruits using a CGM. The best response was recorded after eating 100g of an apple, followed by strawberries, an orange, a banana, and grapes.
- Other factors that impact how fruit affects blood sugar include the ripeness of certain fruits, portion size, food order, food pairing, and individual metabolic factors.
Best (and Worst) Fruit for Blood Sugar and Low Carb Dieting: I Ran the Tests! [Video]
In this video, you’ll learn…
- How fruit affects your blood sugar.
- My blood sugar test results after eating five fruits.
- Additional factors that affect your blood sugar.
Fruit Has Value
Fruits contain vitamins and minerals and a satisfying touch of sweetness. But what if you are trying to control your blood sugar or follow a low carb diet to control your weight? Is fruit OK? The short answer is yes. But fruits vary in their sugar, carbohydrate, and fiber content. These things make some fruits better choices than others.
Fruit and Your Blood Sugar
How much a particular fruit spikes your blood sugar depends primarily on its carb and fiber content and the fruit’s Glycemic Index (GI). The carbs in fruit are mainly from varying amounts of naturally occurring sugars, namely fructose, glucose, and sucrose. All of which can impact blood sugar levels, with fructose causing the smallest initial increase. As for fiber, the more, the better for blunting the blood sugar response.
Based on carbs and fiber alone, a 100g serving of the fruits I tested should rank this way: Strawberries are the best choice, followed by oranges, apples, grapes, and bananas.
If we consider the glycemic index or GI of the fruits, the order would be shuffled somewhat.
Glycemic index uses a scale of 0 to 100 to rank how foods affect blood sugar. Foods with the lowest GI values are best for preventing blood sugar spikes.
However, glycemic index will vary depending on things like where the fruit was grown, and for some fruits, like bananas, the ripeness of the fruit matters.
As a banana ripens, more of its starch content is converted to sugar, raising its GI value. While glycemic index charts are nice references, they cannot be entirely accurate for the piece of fruit sitting in front of you that you are about to eat.
When it comes to your blood sugar response, there is an even bigger outlier that you cannot account for. That outlier is you.
Your Metabolism Affects Your Blood Sugar Response
Your unique metabolism makes a difference, so the results I get are not necessarily the same blood sugar changes that you would experience. Everything from insulin sensitivity to physical activity and even your stress level, sleep quality, and the composition of your gut microbiome contribute to your body’s response to foods.
The only way to be certain that your food choices are having the effect you expect is to monitor your blood sugar. You can do that using a blood glucose monitor from your local pharmacy that tests your blood with a finger prick, or you can use a continuous glucose monitor or CGM.
The CGM I use is provided through Levels. You can learn more about Levels by watching the video at the top of this blog post.
My Fruit Results
How did my body react after eating these fruits? Each fruit was tested on a separate morning on an empty stomach, so there was no food in my system to skew the results.
On day one, I ate 100 grams of a banana at 7 o’clock in the morning.
After two hours, I saw that the banana caused a blood glucose spike of 87 mg/dL, earning a Levels score of 1 out of 10, where 10 is the best score. Eating a banana by itself did not have a good outcome in regard to my blood sugar.
On to day two, and a 100g serving of strawberries. Not a bad way to start my morning, and after two hours, the app showed me that my strawberry breakfast had an OK blood sugar response, causing a blood sugar rise of 36 mg/dL and earning a score of 4 out of 10.
Day three was grapes. Again, it was yummy. And my two-hour blood glucose analysis showed that, like the banana, grapes caused a big spike, raising my blood glucose 90 points above my baseline.
I want to point out that even though the banana and grapes caused a big spike in my blood sugar level, that doesn’t mean my body was harmed by eating them. In fact, the Levels analysis shows me that my body performed perfectly.
I ate the fruit. The sugars in the fruit were processed by my digestive system and sent to my bloodstream. That caused my blood sugar level to go up, which signaled my pancreas to secrete insulin to move that sugar into my cells, where it can be used for energy.
Had it not come down, I would have questions about insulin resistance, so it was very cool and reassuring to watch what my body was doing with the food.
Day four was the day I was most curious about. Apples tend to skirt that middle line as far as carb and fiber content for low-carb dieters. When I ate 100 grams of a Golden Delicious apple, my blood sugar change was very similar to the response I got with the strawberries, causing a rise of 31 mg/dL. Eaten by itself, that was not bad.
On day five, I tested an orange, which is another fruit that is asked about a lot in low-carb circles, so I was curious to see how my body would handle the fruit. For me, 100g of orange fell in the middle of the fruits that I tested, producing an initial spike of 49 points and earning a Levels score of just 2.
Ranking Fruits Best to Worst for Blood Sugar
For me, the best fruit choice for a stable initial blood sugar response turned out to be an apple, followed by strawberries, orange, banana, and grapes.
Of course, it would be best to run these tests multiple days to collect more data. But, even with those additional days, there are factors that would change the blood sugar response I get to these same fruits.
Blood Sugar Factors:
I already mentioned that as some fruits ripen, their sugar content increases. This is true of fruits like bananas, kiwis, pears, and mangos.
Portion size is another factor that influences how much fruit will spike blood sugar. For example, even if you are eating a ripe banana, if you only eat half of it, you’ll experience less of a blood sugar spike.
Food Order and Pairing
Also, if you’re eating a meal, when you consume the fruit and what you eat it with will affect your blood sugar response. I dove into this topic of food order in my last blog post, which you can view here.
I encourage you to read the post for the full story. The basic gist is that simple and quick-digesting carbs are handled best after eating slow-digesting nutrients like protein, fat, and fiber.
In other words, if you know that a certain fruit spikes your blood sugar, don’t have it as an appetizer; eat it for dessert, or just don’t eat it.
And keep in mind that the most important factor is you. Your unique metabolism has a lot to do with how your body responds to foods. For example, you may see a significant blood sugar spike after eating an apple, while your spouse may only see a moderate rise. The only way to be sure is to test. You can do that using a glucose meter or a CGM.
Thank you for reading and have a wonderful week!