Does French onion soup have a lot of carbs?

French onion soup is a classic French dish that is beloved for its rich, savory flavor. This soup is made by slowly caramelizing onions, then adding broth and topping the soup with cheese to create the signature melted, cheesy topping.

With its combination of onions, broth, bread, and cheese, French onion soup seems like it could be a high-carb dish. However, when made properly with reasonable portion sizes, French onion soup can fit into a low-carb or ketogenic diet.

Carb Count in French Onion Soup

The main sources of carbs in French onion soup are:

  • Onions
  • Bread
  • Cheese

Let’s take a look at the carb counts in a typical recipe:


Onions are relatively low in carbohydrates. One medium onion contains around 7 grams of carbs.

In French onion soup recipes, onions are slow-cooked to caramelize their natural sugars and create flavor. This process does not significantly increase their carb count.

For four servings of soup made with two onions, the onion carb count comes out to about 3-4 grams per serving.


The broth provides most of the volume of French onion soup. Standard broths like beef, chicken, and vegetable broth contain almost no carbohydrates.

So the broth does not add any significant carbs to this recipe.


Bread is added to French onion soup by floating a slice on top of the broth and then broiling the soup so the bread gets nicely toasted.

A 1-inch thick slice of baguette contains around 15 grams of carbohydrates. So the bread can be one of the main sources of carbs in the dish.

To reduce carbs, you can opt for a thinner slice of bread, use low-carb bread, or skip the bread altogether. Just be sure to increase the cheese topping if you skip the bread so you still get that characteristic melted cheese layer.


Traditionally, French onion soup is topped with grated gruyere or Swiss cheese. In a 1-cup serving of the soup, you’ll typically find around 1⁄4 cup of grated cheese.

A 1⁄4 cup of grated gruyere or Swiss cheese contains around 1 gram of carbohydrates.

So the cheese adds a very minimal amount of carbohydrates to the dish.

Nutrition Info Per Serving

Based on the analysis above, we can estimate that one serving of French onion soup made with reasonable portion sizes contains:

  • Onions: 3-4 grams carbohydrates
  • Bread: Around 15 grams carbohydrates (can reduce substantially by using low-carb bread options)
  • Cheese: 1 gram carbohydrates
  • Broth: Trace amounts of carbohydrates

So in total, a standard serving of French onion soup has around 20-25 grams of net carbohydrates.

If low-carb bread is used and portion sizes are controlled, you can bring the carb count down to around 10 grams of net carbs per serving.

Low-Carb French Onion Soup Options

If you want to reduce the carb content of French onion soup, here are some tips:

Use Low-Carb Bread

Swap out the regular baguette for low-carb bread options:

  • Low-carb baguette or bread
  • Cloud bread
  • Portobello mushroom cap

Reduce Bread Portion

Use a very thin slice of bread, around 1⁄2 inch thick instead of a full 1-inch slice.

Skip the Bread

You can leave out the bread altogether and just top the soup with cheese. Be sure to use plenty of cheese in that case.

Increase Cheese

Loading up on the cheese topping helps compensate for skimping on bread. Opt for full-fat, low-moisture cheeses for the best texture.

Add Meat

Mix in shredded chicken, beef, or other protein to help make it more of a meal.

Amp Up Vegetables

Add some sautéed mushrooms, leeks, celery, or other low-carb veggies to bulk it up.

Use Lower Carb Broth

Opt for bone broth or vegetable broth instead of potato-based broths.

Moderate Portions

Stick to 1 cup servings instead of oversized bowls.

Skip the Croutons

Some recipes add high-carb croutons on top. Leave these off.

Sample Modified Low-Carb Recipe

Here is an example of a modified French onion soup recipe to make it lower in carbohydrates:


  • 2 tbsp butter
  • 2 large onions, sliced
  • 2 cloves garlic, minced
  • 4 cups beef bone broth
  • 1/4 cup dry white wine (optional)
  • 1 tsp fresh thyme
  • 1 bay leaf
  • 1/4 tsp salt
  • 1/4 tsp pepper
  • 1 cup shredded gruyere or Swiss cheese
  • 4 thin slices low-carb bread


  1. In a large pot, melt the butter over medium heat. Add the onions and cook for 15-20 minutes until deeply caramelized, stirring frequently.
  2. Add the garlic and cook for 1 more minute.
  3. Pour in the broth and wine. Add the thyme, bay leaf, salt, and pepper.
  4. Bring to a boil, then reduce heat and simmer for 10 minutes.
  5. Ladle the soup into oven-safe bowls. Top with 1/4 cup grated cheese.
  6. Top with a slice of low-carb bread.
  7. Broil in the oven for 3-5 minutes until the cheese is bubbly and bread is toasted.

This version uses a double portion of onions to add lots of rich flavor. It skips the potato-based broth and uses bone broth instead. Low-carb bread keeps the carb count reasonable. And loading up on cheese ensures you still get that delicious cheesy topping.

Each serving of this modified recipe contains around 10 grams of net carbs.

The Verdict on Carbs in French Onion Soup

Traditional French onion soup recipes can be moderate to high in carbohydrates, with around 15-30 grams of carbs per serving.

However, with some simple modifications like cutting back on bread, choosing low-carb bread options, and sticking to reasonable portion sizes, you can enjoy French onion soup as an occasional low-carb treat. Just be mindful of your overall carb intake for the day.

Making a few swaps helps reduce the net carbs to around 10 grams per serving, making this soup an option you can work into a low-carb eating pattern once in a while.

So go ahead and enjoy this comforting classic in moderation – just be mindful of portions and make low-carb substitutions where possible.

Ingredient Carbs per serving
Onions 3-4 grams
Broth Trace amounts
Bread (regular) 15 grams
Bread (low-carb) 5 grams
Cheese 1 gram

Frequently Asked Questions

Is French onion soup high in carbs?

Traditional French onion soup can be moderately high in carbs, mainly from the bread. But with low-carb swaps and reasonable portions, you can enjoy it occasionally as part of a low-carb eating plan.

What can I substitute for bread in French onion soup?

Good low-carb bread options include cloud bread, low-carb baguettes, portobello mushroom caps, or very thin slices of regular bread. You can also leave out the bread and just use cheese.

Is French onion soup keto-friendly?

With modifications like skipping the bread, using low-carb bread alternatives, and limiting portions, French onion soup can potentially be part of a keto diet. But servings still need to be tracked to fit within your daily carb limit.

Is Swiss cheese keto?

Yes, Swiss cheese is keto-friendly. It is low in carbs, moderate in protein, and high in fat. One ounce of Swiss cheese has less than 1 gram of net carbs.

Is Gruyere cheese keto?

Gruyere is a good choice for keto. One ounce contains less than 1 gram of net carbs while providing 7 grams of fat and 6 grams of protein.

Can you make French onion soup without bread?

Yes, you can make French onion soup without bread by simply topping it with cheese. You may want to double the amount of cheese used. The soup will have less body but still be full of flavor.

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