Can you eat onions on keto?

In this short article, we will answer the question, “Can you eat onions on keto?” with an in-depth analysis of the ketogenic diet, some characteristics of onions, and the benefits of eating onions on a ketogenic diet. 

Can you eat onions on keto?

Yes, you can eat onions on a keto diet. That is because of their nutrients, low calories, fiber, and flavor (1). Although onions are typically not included in the list of keto-friendly vegetables, if you consume them in moderation, onions, and keto can work together.

The keto diet is a truly low-carbohydrate and high-fat diet that has many characteristics in common with the Atkins and low-carb diets. A ketogenic diet involves considerably decreasing carbohydrate consumption and substituting it with fat (2). This reduction in carbohydrates sets your body into a metabolic phase termed ketosis.

When this happens, the body becomes extra proficient at burning fat for energy. It also transforms fat into ketones in the liver, which can give energy to the brain.

Ketogenic diets can cause notable reductions in blood glucose and insulin levels. This, together with the increased ketone levels, has various health benefits.

What are the benefits of adding onion to your keto diet?

Following are some potential benefits of adding onion to your keto diet:

Rich in antioxidants 

 Onions contain over 25 different types of antioxidants and flavonoids that fight disease. To help protect against various types of disease, it is critical to include a variety of antioxidant-rich foods in your diet (7). 

Reduce cholesterol 

Onions are also high in anti-inflammatory compounds, which may lower your risk of developing chronic inflammatory diseases such as Alzheimer’s or heart disease. Consumption of onions can help lower LDL cholesterol levels, lower high blood pressure, and improve overall vascular function (6). 

Helps to regulate blood sugar levels 

Onions may also be a healthy food choice for people with type 2 diabetes. The addition of onions to the keto diet aids in the normalization and control of blood sugar levels (5). 

When to include onion in a keto diet?

If you have just started your keto diet or it has been 2 to 3 weeks and you are not entirely in ketosis yet, you should not eat onions on the ketogenic diet because they will just delay your progress (2).

However, you can eat onions on a ketogenic diet once you are completely in the ketosis and fat-burning stage, you can slowly begin to raise your carbohydrate consumption, based on your metabolism and the number of calories you burn in a day(3).

You can consume anywhere from 20 to 30 g of net carbs in a day and maintain ketosis.

Usually, when people start a ketogenic diet, it takes them about 3 to 4 weeks to reach a fat-adaptation stage. Once you are acclimated to fats, the best kinds of onions you can consume while on a ketogenic diet are:

  • Green onions/Scallions: 4.4 grams of net carbs per 100 grams of serving
  • Yellow/Brown onions: 6.1 grams of net carbs per 100 grams of serving

How much carbohydrates are in different types of  onion?

On average, a whole raw onion consists of 13.8 g of total carbohydrates, 0 grams of fat, and 2 grams of protein, but it is unlikely you will eat a whole onion in one go.

Yellow/brown onions

Yellow/brown onions are a kind of dry onions with a strong taste. They have a rich onion flavor and fit well for various dishes such as soups, stews, and braises. When they are caramelized, they can become sticky and sweet(9).

Per 100 grams of raw onion serving:

  • Total Carbohydrates: 8.1 g of carbohydrates
  • Fiber: 2 g
  • Net carbohydrates: 6.1 g

Sweet onions

Sweet onions are a type of onions that are not sour. That is due to their low sulfur and high water content when contrasted to other kinds of onion (8). 

Per 100 grams of raw onion serving includes:

  • Total Carbohydrates: 8 g of carbohydrates
  • Fiber: 0.9 g
  • Net carbohydrates: 7.1 g

Red onions

Red onions are cultivars of the onion with a mild and somewhat sweet taste. They have a high content of flavonoids and fiber in comparison to white and yellow onions (11). 

This makes them a great reservoir of antioxidants, and anti-inflammatory agents, they help to decrease the risk of several chronic illnesses.

Per 100 g of raw onion serving includes:

  • Total Carbohydrates: 9.7 g of carbohydrates
  • Fiber: 2.2 g
  • Net carbohydrates: 7.5 g

White onions

White onions are cultivars of dry onions. They have pure white papery peel and sweet, mild white meat. Just like red onions, because of their high sugar value, they have a low shelf life, that lasts up to two days (10).

Per 100 g of raw onion serving includes:

  • Total Carbohydrates: 9.6 g of carbohydrates
  • Fiber: 1.2 g
  • Net carbohydrates: 8.4 g


Shallots are arranged in groups of offset with a head formed of many cloves. Shallots are widely grown for culinary applications and are easily propagated by their offsets (1).

Per 100 g of raw onion serving includes:

  • Total Carbohydrates: 17 g of carbohydrates
  • Fiber: 3.2 g
  • Net carbohydrates: 13.8 g

What are the risks in including onion in your keto diet?

While onions can be a healthy addition to a keto diet, there are some risks to be aware of (12).

Onions are low in carbs compared to other vegetables, but they contain some carbs that can add up if consumed in large quantities. If you’re on a very low-carb or strict ketogenic diet, you may need to limit your onion intake to stay within your daily carb limit. 

The method by which onions are cooked can also affect their nutrient content. Overcooking or frying onions at high temperatures can degrade their nutritional value and produce harmful compounds. To reduce these risks, cook onions gently over low heat or eat them raw whenever possible. 

Consumption of onions can cause bloating, gas, and other digestive discomforts if you have a sensitive gut or digestive issues such as IBS. 


In this short article, we have answered the question, “Can you eat onions on keto?” with an in-depth analysis of the ketogenic diet, some characteristics of onions, and the benefits of eating onions on a ketogenic diet. 


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  1. ​Sagar NA, Pareek S, Benkeblia N, Xiao J. Onion (Allium cepa L.) bioactive: Chemistry, pharmacotherapeutic functions, and industrial applications. Vol. 3, Food Frontiers. 2022. 
  1. ​Ebrahimi-Mamaghani M, Saghafi-Asl M, Pirouzpanah S, Asghari-Jafarabadi M. Effects of raw red onion consumption on metabolic features in overweight or obese women with polycystic ovary syndrome: A randomized controlled clinical trial. Journal of Obstetrics and Gynaecology Research. 2014;40(4).  
  1. ​Sidhu JS, Ali M, Al-Rashdan A, Ahmed N. Onion (Allium cepa L.) is potentially a good source of important antioxidants. J Food Sci Technol. 2019;56(4).  
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  1. ​Nohara T, Fujiwara Y, El-Aasr M, Ikeda T, Ono M, Nakano D, et al. Thiolane-type sulfides from garlic, onion, and Welsh onion. Vol. 75, Journal of Natural Medicines. 2021. 

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