Short answer: yes, popcorn raises blood sugar, because it is a whole grain and mostly starch. But the portion decides how much. Three cups of plain, air-popped popcorn have about 19 grams of carbohydrate and almost 4 grams of fiber, and they usually make a moderate rise. A movie-theater bucket or a bag of caramel corn is a very different snack.
Carbs in popcorn
Popcorn is the whole corn kernel, puffed with air. That means it carries the grain's fiber, and because it is so light, a big-looking bowl doesn't contain much. Figures for plain, air-popped popcorn:
| Serving | Carbs | Fiber | Net carbs | Protein | Calories |
|---|---|---|---|---|---|
| 1 cup (8 g) | 6.2 g | 1.2 g | 5.0 g | 1.0 g | 31 |
| 3 cups (24 g) | 18.7 g | 3.5 g | 15.2 g | 3.1 g | 93 |
| 5 cups (40 g) | 31.1 g | 5.8 g | 25.3 g | 5.2 g | 155 |
Popcorn popped in oil, or microwave popcorn, has about the same carbs per cup but more fat and calories. Kettle corn, caramel corn and other sweet coatings add sugar on top, sometimes a lot of it, so check the label on those.
Glycemic index and glycemic load
Plain popcorn has a glycemic index of about 65, which puts it in the medium band (56 to 69). On its own, the glycemic index only describes how fast a food's carbs turn into blood glucose, not how many carbs you actually eat.
Glycemic load takes the portion into account. For three cups, it comes out at about 10, at the top of the low band. That is why a measured bowl of popcorn tends to behave better than its glycemic index suggests, and why a large bucket doesn't. You can look up other foods in our glycemic index chart.
What happens after you eat it
The starch in popcorn is digested into glucose fairly quickly, so most people see a rise that starts within the first half hour and peaks somewhere around 45 to 90 minutes. Fiber slows that down a little. How high it goes depends on the portion, on what else you ate, on the time of day, and on you: two people can respond quite differently to the same bowl.
For many adults with diabetes, the American Diabetes Association suggests a target of under 180 mg/dL (10.0 mmol/L) one to two hours after starting a meal or snack. Your own targets may be different, so go by what your care team has set.
How to eat popcorn with a smaller rise
- Measure it. Pop it at home and put three cups in a bowl, instead of eating from the bag or the bucket.
- Keep it plain. Air-popped or with a little oil. Season it with salt, spices, herbs, nutritional yeast or a little parmesan instead of sugar.
- Add some protein or fat. A handful of nuts or a piece of cheese alongside tends to slow how quickly the carbs arrive.
- Have it after a meal, not instead of one. On an empty stomach, the same bowl often gives a sharper rise.
- Move a little afterwards. A ten-minute walk helps your muscles use some of the glucose.
Check your own response
The numbers above are averages. The only way to know how popcorn behaves for you is to measure it a few times. Log the popcorn in InRange with the amount you ate, and once you have eaten it a few times, the dish gets its own numbers: how far it raises you on average, when it peaks, and how long it takes you to get back in range. Then you can compare the plain bowl with the buttered one, or the afternoon snack with the late-night one.
Common questions
Is popcorn good for people with diabetes?
It can fit well. Plain popcorn is a whole grain with fiber and few calories per cup. The things to watch are the portion and anything sweet added to it.
How much popcorn can someone with diabetes eat?
A common snack portion is about three cups, around 15 to 20 grams of carbohydrate. How much works for you depends on your plan and your own response.
Does microwave popcorn raise blood sugar more?
Per cup the carbs are about the same. Microwave popcorn has more fat, which can slow the rise, and some flavors add sugar. Check the label for the carbs per serving.
Is popcorn low carb?
Not really. At about 6 grams of carbs per cup, it is a moderate-carb snack that happens to be light and filling.
Sources
- U.S. Department of Agriculture, FoodData Central. Snacks, popcorn, air-popped.
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International tables of glycemic index and glycemic load values: 2008. Diabetes Care. 2008;31(12):2281–2283.
- American Diabetes Association. Standards of Care in Diabetes, section 6: Glycemic goals and hypoglycemia.