Can You Eat Popcorn on a Keto Diet? Nutritionists Explain

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This nutritious whole-grain snack is filling, but low in calories.

The ketogenic diet is currently one of the most popular low-carb eating plans, but as with any strict diet, it can be tricky to figure out what foods (especially snacks!) fit into the plan. When it comes to healthy and delicious snacks, popcorn is a staple. In fact, Americans eat an average of 45 quarts of popcorn annually, according to the Popcorn Board (an organization that consists of popcorn companies). So if you’re trying to follow a keto diet, you’re probably wondering if popcorn is a keto-friendly food — so we spoke with nutritionists to find out everything you need to know.

First, the basics: Popcorn is a specific type of maize called zea mays everta. After the ears of corn are harvested, they’re dried out and then the kernels are removed. However, a small bit of moisture remains in the hard kernel so when the kernel is heated, the moisture vaporizes and pressure builds within until it eventually "pops" and expands into the fluffy, yummy snack we all love. Because the kernel remains attached (albeit in pieces) to the soft flesh, popcorn is technically a whole-grain snack. When eaten plain, it's low in sugar and fat and contains some fiber — so overall it's considered a healthy snack.

Here are the nutrition facts for 1 cup of plain air-popped popcorn:

The ketogenic diet originated in the 1920s as a treatment approach for children with epilepsy, but it has risen in popularity in recent years as a way to lose weight. The general goal of a keto diet is to primarily eat fats and protein while limiting your intake of carbohydrates to a very small amount. "Carbohydrates are normally stored in the liver and muscles to be used for energy between meals," explains Lisa Andrews, M.Ed., R.D., owner of Sound Bites Nutrition in Cincinnati, Ohio. "But in the absence of carbohydrates, the body is forced to break down fat into ketones for calories/energy." When ketones accumulate in your blood, that's a state known as "ketosis."

The numbers vary for every individual, but most people trying to stay in ketosis allow carbohydrates to make up only 5 to 10% of their daily calories. "This is much lower than the U.S. Dietary Guidelines, which advise between 45 to 65% of total calories coming from carbs," says Andrews. Essentially, when you start a keto diet, you usually aim for around 20 grams of carbohydrates per day, according to Rissetto, and then you can adjust your intake to see what your upper limit is — usually around 50 grams. "You can tell if you are in ketosis by using keto sticks to check for ketones in your urine," explains Andrews. "A ketone breath analyzer is also available to check for ketosis."

"The thing is, though, that your body, in the absence of carbohydrates, will make carbohydrates," says Vanessa Rissetto, M.S., R.D., co-founder of the nutrition coaching platform Culina Health. "The liver will do that — it's called gluconeogenesis. So you're not going to go one day of not eating carbs and automatically be in ketosis. It happens over time because your body is used to using carbs." That means you have to stick with the diet for a decent amount of time to lose weight (and if you go off the diet, there's a chance you’ll regain any pounds you dropped). Of course, carefully evaluating everything you eat can be tiring over time. "It's really not fun — the mental aspect of it is really tough to do," says Rissetto.

On top of that, even though you may lose weight, there are long-term health issues to consider with the keto diet. "Excessive carbs from refined foods — sweets, chips, snack foods, fast food — are not the best for overall health, but a keto diet lacks variety and can be low in fiber, which also raises the risk for certain diseases including heart disease and cancer," Andrews points out.

The best thing you can do is talk to your doctor and/or a nutritionist first to see if a keto diet is right for you.

Back to the snack in question: The answer is yes, you can eat popcorn on a keto diet — but there are a few things to keep in mind. Once you figure out how many daily carbs your body can take in to remain in ketosis, you can divvy up your allotment however you like, but popcorn can easily fit in a ketogenic eating plan. "For all intents and purposes, it is a keto-friendly food," says Rissetto. "It's going to fill you up, it's not high on the carb count and it has a little bit of fiber."

The key is not to go overboard — 1 cup of air-popped popcorn has only 6 grams of carbs, but if you eat 3 cups, that's 18 grams and likely more than half of your daily carbs. "The issues starts to happen when you start adding different things to it," Rissetto says. Savory things like butter, Parmesan cheese, seasonings or a tiny bit of hot sauce are within the limits of the diet according to Rissetto, but sugar, caramel and chocolate are probably not.

You also have to think about how your popcorn is prepared. "Air-popped popcorn is the most nutritious because it has the least amount of fluff — chemicals, food coloring, salt, fat — added to it via processing," says Andrews. On the other hand, she says, traditional microwave popcorn contains a fair amount of hydrogenated oils (unless it's labeled 94% fat-free) and sodium, as well as diacetyl, a buttery-flavored chemical that's been linked with lung disease in employees at popcorn-processing plants. "Movie-style popcorn, contains Flavacol— an ingredient containing salt, artificial butter flavor, Yellow #5 and Yellow #6. It also contains hydrogenated soybean oil meant to mimic butter," she adds.

Editor's note: Weight loss, health and body image are complex subjects — before deciding to go on a diet, we invite you to gain a broader perspective by reading our exploration into the hazards of diet culture.

If you’re looking for more snacks to eat on a keto diet, consider these suggestions from Andrews:

Kaitlyn Phoenix is a senior editor in the Hearst Health Newsroom, where she reports, writes and edits research-backed health content for Good Housekeeping, Prevention and Woman's Day. She has more than 10 years of experience talking to top medical professionals and poring over studies to figure out the science of how our bodies work. Beyond that, Kaitlyn turns what she learns into engaging and easy-to-read stories about medical conditions, nutrition, exercise, sleep and mental health. She also holds a B.S. in magazine journalism from Syracuse University.

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