Are onions OK for keto?

Quick Answer

Onions can be included in a ketogenic diet in moderation. One small to medium onion contains around 9-15 grams of net carbs, so they should be limited to stay within your daily carb allowance on keto. Red onions tend to be lower in carbs than white or yellow onions. Overall, onions are a healthy low-calorie vegetable that provide antioxidants, vitamin C, and fiber. Enjoy onions cooked or raw, but track your portions to keep carbs in check.

Onion Nutrition Facts

Here are the nutrition facts for a medium raw onion (around 110g):

Calories 44
Fat 0.1g
Carbs 10g
Fiber 1.7g
Net Carbs 8.3g
Protein 1.1g

A medium onion contains about 10g total carbs and 1.7g of fiber. So the net carb count comes out to 8.3g per onion.

Net carbs are calculated by subtracting fiber from total carbs, as fiber does not impact blood sugar or ketosis.

The exact carb count can vary slightly depending on the specific size and type of onion. But in general, medium raw onions have around 8-9g net carbs each.

Carbs in Different Onion Types

The carb content can fluctuate depending on the onion variety:

Onion Type Net Carbs per 100g
Yellow onion 9g
White onion 9g
Red onion 7g
Shallots 17g
Leeks 12g
Spring onions 5g

Red onions contain slightly fewer carbs than other varieties. Shallots and leeks are higher in carbs than common bulb onions. Spring onions (also called scallions) are the lowest carb onion option.

So in terms of carb content, red and spring onions are the best choices for keto. But all types can fit into a keto diet in moderation.

Onions for Keto Meals and Recipes

Here are some tips for including onions in your ketogenic meal plan:

Use Smaller Portions

Limit onion portions to about 1/4 to 1/2 a medium onion per serving. This will provide flavor while keeping net carbs in the 3-5g range. Track your intake and account for the carbs in your daily tally.

Go Raw or Cooked

Enjoy onions raw in salads, salsas and dressings. Raw onion provides a crunchy texture and sharp flavor.

Cooking mellows the onion’s bite and brings out the sweetness. Onions pair well cooked into curries, stir-fries, omelets and more. Caramelizing onions via low, slow cooking brings out the natural sugars.

Substitute with Spring Onions

Trade regular bulb onions for slender spring onions. With only 5g net carbs per 100g, spring onions allow you to use more onion for fewer carbs. Slice up the white and light green parts raw for salsa or tacos.

Use Onion Powder

Onion powder is a low-carb swap for fresh onions. Make sure to get pure onion powder without added sugars or starches. Use it to season eggs, meat, vegetables and soups.

Try Shallots and Leeks

Although higher in net carbs than other types, shallots and leeks add great flavor when used sparingly. Sautee thinly sliced shallots with olive oil as a gourmet burger topping. Add leeks to bone broth soups.

Sautée or Caramelize

Sautéing and caramelizing coaxes out onions’ natural sweetness. Cook over medium-low heat in butter or olive oil until golden brown. Then use them to top keto pizzas, casseroles, meatloaf and more.

Pickle Raw Onions

Pickling raw onions in vinegar draws out their sharp bite. Add a tangy crunch to sandwiches, wraps and salads with pickled red onions. Just watch the carb count in packaged pickled onions, as some have added sugar.

Onion Health Benefits

Onions provide some important health benefits, which make them a great addition to a low-carb diet:

Rich in Antioxidants

Onions contain antioxidants like quercetin and anthocyanins. These compounds fight free radicals and inflammation to support heart health and manage blood sugar.

Prebiotic Effects

The fiber in onions acts as a prebiotic by feeding beneficial gut bacteria. Onions promote a healthy microbiome.

Anti-cancer Properties

Studies show onions may help inhibit the growth of certain cancers like stomach, colon and ovarian cancer. Onions’ sulfur compounds and quercetin are thought to contribute to these anti-cancer effects.

Promote Heart Health

Eating more onions correlates with improved cholesterol levels and lower heart disease risk. The antioxidants in onions help prevent LDL cholesterol from oxidizing and forming arterial plaque.

May Boost Bone Density

Some of the antioxidants in onions, like quercetin, are linked to increased bone mineral density. More research is needed, but onions look promising for protecting bone health.

Antibacterial Properties

Onions have antibacterial effects against common foodborne pathogens like E. coli and salmonella. Quercetin is considered one of the compounds responsible for these antibacterial benefits.

Are Onions Keto-Friendly?

Onions can fit into a keto diet when consumed in moderation. A 1/2 medium onion contains around 5-7g net carbs, so it’s easy to incorporate into your daily carb allowance.

Here is a recap on including onions on keto:

– Enjoy onions cooked or raw to add flavor and nutrition to meals.

– Stick to about 1/4 to 1/2 an onion per serving.

– Favor low-carb red and spring onions when possible.

– Use onion powder as a zero-carb substitute.

– Try caramelizing or pickling onions to maximize flavor at lower volumes.

– Account for the net carbs when tracking your macros.

With a little mindfulness of portions, onions can be included and enjoyed as part of a ketogenic eating pattern.

Keto Onion Recipes

Here are some delicious keto recipes featuring onions:

Caramelized Onion and Mushroom Frittata

This vegetable-packed frittata makes the perfect keto brunch. Caramelized onions blended with cremini mushrooms, spinach and cheese.

Keto French Onion Soup

Satisfy cravings the low-carb way with this creamy keto take on classic French onion soup. Topped with melted cheese for added richness.

Keto Beef and Broccoli Stir Fry

Tender steak strips meet crisp broccoli florets and carrots in this easy keto stir fry. Finished with sesame seeds and green onions.

Cauliflower Rice Taco Bowls

Loaded taco bowls with seasoned cauliflower rice, ground beef, cheese, avocado and a scoop of fresh pico de gallo.

Keto Breakfast Quesadillas

These quick breakfast quesadillas are filled with fluffy scrambled eggs, onions, peppers and gooey shredded cheese.

Zucchini Lasagna Skillet

All the flavors of lasagna in easy, one-pan skillet form. With zucchini noodles, ground meat sauce and an oniony ricotta filling.

Keto Cheeseburger Soup

Comforting cheeseburger soup made keto-friendly. Cooked with onions, celery, heavy cream and topped with chopped dill pickles.

Onion Alternatives for Keto

In addition to onion powder, here are some alternative low-carb ingredients that provide savory oniony flavor:


Chopped shallots can be used in place of onions. Their mild sweet flavor works well cooked or raw. Remember that shallots are slightly higher in carbs than bulb onions.

Scallions (Green Onions)

Sliced scallions make a great onion swap in raw dishes like salsa, guacamole and salad dressings. They have just 5g net carbs per 100g, much less than regular onions.


For a milder onion taste, use chopped leeks in soups, stews and sautés. Leeks are higher in carbs than other onion types, so use them sparingly.


Garlic provides a punch of flavor for little carbs. Use minced or granulated garlic in place of onions in many recipes.

Asafoetida Powder

This Indian spice has an onion-garlic taste. Add a pinch to dishes in place of onion. Beware, a little goes a long way due to its potent smell.


Fresh chives give a light onion and garlic flavor. Chop and use raw as a garnish, or add to compound butter.

Sample Keto Meal Plan with Onions

Here is a one day keto meal plan incorporating onions:


– Mushroom and Onion Omelet: Eggs, onions, mushrooms, cheese
– Keto Coffee with heavy cream


– Tuna Salad Wraps: Canned tuna mixed with mayo, onion, celery on lettuce leaves
– Hard boiled eggs
– Dill pickle spears


– Sheet Pan Fajitas: Flank steak, onions, peppers sheet pan-roasted
– Guacamole: Avocado, lime, onion, cilantro
– Romaine salad with avocado and onion vinaigrette


– Bacon-wrapped jalapeno poppers stuffed with cream cheese and caramelized onions
– Cucumber slices with onion dip (sour cream mixed with onion powder and dill)

As shown in this sample menu, it’s easy to incorporate onions into keto-friendly meals. Enjoy them cooked down in omelets, mixed into tuna and egg salad, or caramelized for fajitas and poppers.

Onion Substitutes for Allergies

For those with an intolerance or allergy to onions, these low-carb substitutions add lots of flavor:

– Asafoetida powder

– Garlic

– Leeks

– Scallions

– Shallots

– Onion powder (use onion-free brand)

– Dried onion flakes (use onion-free brand)

– Chives

– Celery

– Fennel

As always, check labels to ensure any prepared foods or seasonings are onion-free. Get creative combining other alliums, herbs and spices for flavor in cooking.

Low Carb Onion FAQ

Are onions high in carbs?

Onions contain around 10g carbs per 100g. After subtracting fiber, the net carbs are around 7-9g per medium onion. They are lower in carbs than many starchy vegetables but higher than most non-starchy veggies.

Can you eat onions on the keto diet?

Yes, onions can be included on keto. Enjoy onions cooked or raw while limiting portions to keep net carbs minimal. About 1/4 to 1/2 an onion is a good serving size. Prefer low-carb red and spring onions when possible.

What is the lowest carb onion for keto?

Red onions and spring onions (also called scallions or green onions) are the lowest carb varieties. Red onions have around 7g net carbs per 100g while spring onions have just 5g.

Are green onions OK on keto?

Yes, green onions are one of the best options for keto. With only 5g net carbs per 100g serving, green onions, scallions and chives can be used more liberally than other types.

Can you eat onions on keto?

It’s absolutely possible to incorporate onions into a ketogenic diet. A good rule of thumb is limiting to about 1/4 medium onion per main meal. Favor raw or cooked red and green onions over white and yellow varieties. Track servings and net carbs to stay within your daily carb target.

Are Pickled Onions keto-friendly?

Pickled onions can fit into keto diets when homemade or from brands without added sugars. Some store-bought pickled onions have high-carb ingredients like corn syrup or honey. Check labels and aim for versions pickled in vinegar alone.


Onions can be enjoyed in moderation on a ketogenic diet. While relatively higher in carbs than some vegetables, onions still provide good nutrition and flavor for under 10g net carbs per serving.

Red onions and scallions are great low-carb options. Use raw or cooked onions to add taste and crunch to keto meals. Substitute dried onion powder or try caramelized onions to maximize flavor in smaller portions.

Include onions smartly in your keto meal plan, tracking quantities to keep net carbs in check. With some care taken to control portions, onions can be a tasty addition to a healthy low-carb lifestyle.

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