How many calories in a serving of caramelized onions?

Caramelized onions are a delicious way to add flavor to many dishes. But like any ingredient, they also add calories. So how many calories are actually in a serving of caramelized onions?

What are Caramelized Onions?

Caramelized onions are simply onions that have been cooked low and slow over medium or medium-low heat. The natural sugars in the onion caramelize, resulting in onions that are intensely sweet and flavorful.

During the lengthy cooking process, moisture evaporates from the onion, concentrating its natural flavors. The onions take on a melted, jammy texture and turn a rich, deep brown color as their sugars caramelize.

Caramelized onions are ideal for serving as a topping, mixing into dips and spreads, or adding to recipes for an extra punch of sweet onion flavor. You’ll find them used in everything from burgers to pizza, sandwiches, savory tarts, soups, and more.

Nutrition Facts for Onions

To determine how many calories are in caramelized onions, we first need to look at the nutrition facts for raw onions. Here are some key macronutrients for a 1/2 cup serving (approx. 80 grams) of raw sliced onions (1):

  • Calories: 32
  • Carbohydrates: 7.4 g
  • Fiber: 0.9 g
  • Sugar: 3.8 g
  • Protein: 0.9 g
  • Fat: 0.1 g

As you can see, raw onions are very low in calories and fat. Their primary macronutrient is carbohydrates in the form of natural sugars.

Calorie Changes During Caramelization

When onions are caramelized, the majority of their water evaporates. The volume of the onions decreases significantly as their moisture cooks off.

This concentration effect results in the macros becoming more concentrated as well. Though the total macronutrients remain largely the same, they become packed into a smaller serving size.

For example, if you start with 1 cup of sliced raw onions and cook them down into 1/4 cup of caramelized onions, you’ve reduced the total volume by 75%. So the calories and macronutrients become concentrated into that smaller volume.

There is also a slight increase in overall sweetness as the natural sugars caramelize. So the carb, sugar, and calorie count increase slightly.

Calories in a Serving of Caramelized Onions

With all that in mind, here is the approximate calorie count for a typical serving of caramelized onions:

  • 1 tablespoon caramelized onions: approx. 15 calories
  • 1/4 cup caramelized onions: approx. 60 calories
  • 1/2 cup caramelized onions: approx. 120 calories

These counts are based on starting with approximately 1 cup of sliced raw onions and cooking them down into 1/4 cup caramelized onions. This concentrates the 32 calories from 1 cup of raw onions into 60 calories for the reduced 1/4 cup volume after caramelization.

Calories Can Vary

Keep in mind that the exact calorie count can vary depending on:

  • Type of onion used – yellow, white, red, shallots, etc.
  • Precise volume measurements before and after caramelizing.
  • How browned the onions become – lightly vs. deeply caramelized.
  • How much oil or fat is used to cook them.

But the above figures still provide a good general guideline for how many calories are in a serving of these sweetened onions.

Nutrition Benefits of Caramelized Onions

In addition to providing a flavor boost, caramelized onions offer some great nutrition perks. Here are some of their top health benefits:

Rich Source of Disease-Fighting Antioxidants

Onions contain powerful antioxidants like quercetin and anthocyanins. Caramelizing onions enhances their antioxidant capacities even further (2).

Increase Absorption of Key Nutrients

Certain compounds in caramelized onions can boost the absorption of nutrients like beta-carotene from other foods when eaten together. Beta-carotene is converted to active vitamin A in the body (3).

May Provide Anti-Cancer Benefits

Some studies have found the antioxidants in caramelized onions may help inhibit the growth of certain cancer cells, like colon and stomach cancer (4).

Help Regulate Blood Sugar

Despite their sweet taste, caramelized onions have a low glycemic index. They can help regulate blood sugar when part of a balanced diet (5).

Anti-Inflammatory Effects

Quercetin and other compounds may help reduce inflammation. Chronic inflammation is linked to many diseases (6).

Prebiotic Effects

The indigestible fibers in caramelized onions act as prebiotics. They help feed beneficial probiotic bacteria in the gut microbiome (7).

Contain Inulin

Inulin is a type of prebiotic fiber found in onions. It supports digestive health and helps enhance calcium absorption (8).

As you can see, caramelized onions provide some great health bonuses. They add both rich flavor and nutrition to your diet.

Should You Worry About the Calories?

In moderation, the calories in caramelized onions should not be a major concern for most people. After all, we are talking about vegetables!

The recommended serving size for caramelized onions is just 1-2 tablespoons. At around 15 calories per tablespoon, they make an excellent low-calorie flavor booster.

Even a larger 1/2 cup portion only tallies up around 120 calories. That’s not too shabby for a side dish packed with antioxidants, fiber, and disease-fighting compounds.

Just be mindful of any extra oils, butter, or other calorie-adding ingredients used during the caramelization process. Try cooking them in broth or water instead of oil when possible.

For most recipes, even a couple tablespoons of onions cooked with a tsp of olive oil won’t add too many extras calories.

Ways to Use Caramelized Onions

Here are some delicious ways to use caramelized onions to take dishes to the next level:

On Sandwiches and Burgers

Burgers, paninis, grilled cheese – you name it! Caramelized onions make an amazing sandwich topping.

In Salads

Add sweet, melty onions to hearty grain and greens salads. They pair perfectly with bold flavors like goat cheese.

As a Pizza Topping

Drizzle caramelized onions over homemade or store-bought pizza. They’re delicious alongside vegetables or cured meats.

In Quiches, Frittatas and Stratas

Mix caramelized onions into egg bakes like crustless quiche or spinach strata for savory depth.

In Soups and Chilis

Stir them into beef chili, French onion soup, or pureed vegetable soups for extra flair.

In Pasta Dishes

Toss some crispy, caramelized onions into your next pasta bake. They’ll add texture and flavor.

In Braises and Stews

Beef stew, short ribs, vegetable braises – the flavors of caramelized onions just enhance these cozy dishes.

As a Breakfast Side

Wake up to next-level eggs. Top omelets, scrambles and hashes with sweet, savory caramelized onions.

In Flatbreads

Mix them into homemade naan or focaccia for an easy way to make flatbreads shine.

In Casseroles or Gratins

From green bean to potato to mac and cheese – fold caramelized onions into your favorite casserole.

On Meat

Can’t decide between burgers or steak? Top seared meats with an onion garnish for bonus flavor.

In Spreads and Dips

Blitz them into bean dips, cheese balls, creamy spreads and savory sauces.

On Roasted Vegetables

Toss carrots, potatoes, squash and more with glistening, browned onions.

The options are nearly endless for using caramelized onions. Get creative and let them enhance your cooking!

Tips for Preparing Caramelized Onions

It’s easy to caramelize onions right on your stovetop with just a couple tips:

  • Slice the onions thinly to increase the surface area.
  • Use a heavy pan that will distribute heat evenly.
  • Cook the onions “low and slow” on medium or medium-low.
  • Stir occasionally to make sure nothing burns.
  • Be patient – the process takes 30-60 minutes.
  • Let the onions go deep golden brown for the best flavor.

And that’s really all there is to it! With frequent stirring and careful cooking, you’ll achieve sweet, richly caramelized onions every time.

Save Time with a Slow Cooker

For ultra-easy caramelized onions, a slow cooker does all the work. Simply:

  1. Add sliced onions to a slow cooker.
  2. Stir in a bit of olive or avocado oil.
  3. Season with salt and pepper.
  4. Cook on low heat for 4-6 hours.
  5. Stir occasionally and adjust seasoning.

The extended low heating gently caramelizes the onions to perfection. They can be made in large batches this way too.

How to Store Caramelized Onions

Properly stored, caramelized onions last around 1 week in the refrigerator or up to 6 months in the freezer. Here are some storage tips:


  • Allow onions to cool completely before refrigerating.
  • Store in an airtight container for 1 week max.
  • Add a splash of vinegar to help them keep longer.


  • Freeze cooled onions in resealable plastic bags.
  • Lay bags flat in freezer for efficient storage.
  • Thaw in fridge before using in recipes.
  • They’ll keep for about 6 months frozen.

Storage Considerations

A few things to keep in mind:

  • Onions stored in oil don’t freeze well due to food safety.
  • Avoid freezing large batches – divide into portions.
  • Onions lose some texture after freezing.
  • Store in original cooking liquid or drizzle with oil to prevent drying.

With proper storage methods, you can easily keep a supply of caramelized onions ready for recipes.

In Conclusion

When cooked down, the natural sugars in onions caramelize to create a sweet, jam-like topping or mix-in. While the calorie count increases slightly for caramelized versus raw onions, a typical serving still provides just around 60-120 calories.

In moderation, enjoying these flavorful onions can be part of a healthy diet. They supply beneficial prebiotics, antioxidants, fiber and disease-fighting compounds.

Add a touch of rich, sweet onion flavor to sandwiches, pizzas, salads, egg dishes, pasta, soups, stews, roasted veggies, and more. Or simply enjoy them as a savory side dish.

So don’t be afraid to give caramelized onions a try. Just a tablespoon or two adds a whole new dimension of taste! And you’ll gain all the nutritional bonuses of onions in their most delicious form.

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