Onions are packed full of so many health benefits, they are a superfood! But are onions keto? And what about cooking them, are sautéed onions keto-friendly? Let’s take a closer look at this sweet vegetable!

Photo of sauteed onions in a black frying pan with a wooden spoon. Banner says "are onions keto? Sauteed, raw, powder, and more".

❤️ Why you will love this post

  • Onion facts: Check out these 5 facts about onions! Number 4 may surprise you =]
  • Nutritional details: I’ve included some information about each kind of onion, including calories, total grams of carbs, and also the total grams of net carbs, which is the total carbohydrates minus the grams of fiber when looking at American nutrition labels. In the UK, you don’t need to subtract the fiber from the carbs as they already calculate it for you.
  • Serving suggestions: What do onions go on? These are my 3 favorite ways to cook with onions when I’, working on weight loss through the keto diet.
  • Recipe ideas: Keto dieters can get busy in the kitchen with these delicious side dish recipes and keto meal ideas! Perfect for any low carb diet.

🧅 5 Fun Onion Facts

  1. They’ve pretty much always been around: Yes, onions were even eaten by our prehistoric ancestors!
  2. In preparation for the ancient Olympics in Greece, athletes would eat lots of onion, drink onion juice, and rub onions all over their bodies. I’ll bet they smelled great. Onions are now shown to improve circulation so they were definitely onto something there!
  3. They have cousins! Onions are part of the same family as a whole variety of other low carb veggies in your pantry like garlic, shallots, chives, leeks, and scallions. If you’ve tried these, I think you’ll agree that they have a pleasant onion taste.
  4. Largest onion: The largest onion ever grown was right here in the UK! Tony Glover’s onion in September 2014 was a whopping 8.5kg (18lbs 12oz).
  5. Health benefits of onions: Onions are a great source of antioxidants, particularly the heart health-boosting flavonoid quercetin. It also reduces blood sugar and promotes healthy bones. It’s a great source of vitamin C, and B vitamins like B9 (folate) and B6.

✅ Different types of onions and their net carbs per 100g

Keep in mind that large raw onions weigh around 250g (7 ounces), medium onions are around 160g (6 ounces), and small onions are about 125g (4.5 ounces). Also, it’s important to point out that you’d rarely eat an entire onion. If a dish called for one large onion but makes 6 portions, then the carb count coming from the onion would be 2.9g net carbs per portion.

Yellow onions & white onions

Per 100g

  • Calories: 40
  • Total carbs: 9g
  • Net carbs: 7g

Per 250g (large)

  • Calories: 100
  • Total carbs: 22.5g
  • Net carbs: 17.5g

Per 160g (medium onion)

  • Calories: 64
  • Total carbs: 14.4g
  • Net carbs: 11.2g

Per 125g (small, about 1 cup of onions, chopped)

  • Calories: 50
  • Total carbs: 11.25g
  • Net carbs: 8.75g

Red onions

Per 100g

  • Calories: 39
  • Total carbs: 9.1
  • Net carbs: 8g

Per 250g (large)

  • Calories: 97.5
  • Total carbs: 22.75g
  • Net carbs: 20g

Per 160g (medium)

  • Calories: 62.4
  • Total carbs: 14.56g
  • Net carbs: 12.8g

Per 125g (small)

  • Calories: 48.75
  • Total carbs: 11.4g
  • Net carbs: 10g
Sauteed onions in a black frying pan with a wooden spoon.

Vidalia onions (sweet onions)

Per 100g

  • Calories: 32
  • Total carbs: 7.6g
  • Net carbs: 6.7g

Per 250g (large)

  • Calories: 80
  • Total carbs: 19g
  • Net carbs: 16.75g

Per 160g (medium)

  • Calories: 51
  • Total carbs: 12g
  • Net carbs: 10.7g

Per 125g (small)

  • Calories: 40
  • Total carbs: 9.5
  • Net carbs: 8.4g

Green onions, spring onions, & scallions

Per 100g

  • Calories: 32
  • Total carbs: 7g
  • Net carbs: 4.4g

Pearl Onions

Per onion (15g)

  • Calories: 6.6
  • Total carbs: 1.5g
  • Net carbs: 1.3g

Dried onions (onion flakes)

Per 1oz/28g:

  • Calories: 88
  • Total carbs: 19.2g
  • Net carbs: 15.8g

Onion powder

Per tablespoon:

  • Calories: 24
  • Total carbs: 5g
  • Net carbs: 4g

🤔 What type of onion is best for a keto diet?

Green onions (also known as scallions or spring onions) have the lowest carb content per 100g, and can easily be added to dishes on a low-carb diet. When it comes to adding a more regular onion, surprisingly the Vidalia is the best option, coming in at 12 grams of carbohydrates, and 10.7 g net carbs. That means if you chopped up a medium-sized Vidalia onion and added it to a dish that made 6 portions, each portion would have just 1.8 grams of net carbohydrates from the onion. That’s easy to fit into a keto diet!

🤷‍♀️ Are Sautéed Onions Keto Friendly?

Sauteed onions in a black frying pan with a wooden spoon.

They sure can be! It depends on how much onion you eat in one go. If you sauté a medium-sized yellow onion in olive oil and divide it by 4, you would have 4.4g net carbs per portion. If that fits into your macros for the day then you have nothing to worry about!

When you sauté onions, they taste much sweeter than regular onions. This is because when they are cooked, the moisture levels are reduced allowing the natural sugars and sweetness of the onions to shine through. The cooking process doesn’t increase the carbohydrates at all, it just breaks down the other parts of the onion that are less sweet, making them taste sweeter.

As long as you pair the caramelized onions with some other fats, keto vegetables, and protein, you can easily fit this into a meal and not affect your state of ketosis.

❓ How to use onion on a keto or low-carbohydrate diet

  • Add small amounts of raw or sauteed onions to burger bowls
  • Add a little to a salad – you may only need a couple of teaspoons of raw onion!
  • Cook them in large casseroles (see some ideas below!)

🍽️ Keto recipes with onion

Red, white, or yellow onions

Green onions/spring onions

Onion powder

And, of course, the best way to serve oven-baked sausages or Air Fryer Sausage is with some sautéed onions on a keto bun!

🪄 The bottom line

Onions are one of the best and healthiest low-carb vegetables to eat on any diet. It’s packed with essential nutrients and tastes delicious to boot. A good source of fiber, fitting this vegetable into your ketogenic diet is all about serving size. Carbs-wise, it’s best not to eat a whole onion in one go, however, a little goes a long way when you’re cooking onions. Adding one or half an onion into a large dish that serves 4-6 people should be absolutely fine for your daily net carb intake. So go ahead and enjoy that natural, sweet flavor!

Sauteed onions in a black frying pan with a wooden spoon.

😋 More keto recipes and posts you will love

What’s your favorite way to eat onions? I’d love to know <3 Tag me (@makehealthyrecipes) on Facebook and InstagramPin it on Pinterest, and please leave a comment below! Don’t forget to subscribe to the email list (top right of this page) for sparkly new recipes in your inbox.

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