How Many Calories Are in 200g of Red Onion? A Complete Nutritional Breakdown

December 7, 2025 •

3 min read

According to USDA data, raw onions contain approximately 40 calories per 100g, meaning that 200g of red onion has roughly 80 calories. This low-calorie, nutrient-dense vegetable is a versatile addition to many dishes, offering significant health benefits alongside its potent flavor.

Quick Summary

A 200g portion of raw red onion contains around 80 calories, along with substantial vitamins, minerals, and potent antioxidants. The final calorie count can vary slightly depending on the cooking method used.

Key Points

Calorie Count: 200g of raw red onion contains approximately 80 calories, based on standard nutritional data.
Rich in Antioxidants: Red onions are packed with anthocyanins and quercetin, powerful antioxidants linked to heart health and anticancer properties.
Low-Fat and High-Fiber: A 200g serving contains minimal fat and a good amount of dietary fiber, supporting digestive health and weight management.
Cooking Method Affects Calories: Adding oil or butter during cooking, like sautéing, will significantly increase the calorie count, while boiling or roasting maintains a low caloric value.
Nutrient Dense: Beyond calories, red onions provide valuable vitamins like C, B6, and folate, as well as minerals such as potassium.
Heart and Bone Health: Regular consumption is linked to better heart health, blood sugar regulation, and increased bone density.

The Calorie Count Explained

The number of calories in 200g of red onion is surprisingly low, making it a staple for anyone mindful of their caloric intake. Based on average nutritional data, a 200g serving of raw red onion contains approximately 80 calories. This figure is derived from the fact that raw onions, in general, contain about 40 calories per 100 grams. This makes red onion a low-energy food, meaning it provides a feeling of fullness for very few calories, aiding in weight management and healthy eating habits.

Raw vs. Cooked Red Onion Calories

It's important to note that the preparation method can influence the final calorie count. While the core nutritional value remains similar, added ingredients or the cooking process itself can alter the numbers. For instance, sautéing red onions in oil or butter will increase the total caloric content significantly. On the other hand, cooking methods like boiling or roasting without added fats will have a minimal impact, potentially increasing the calorie density slightly as water evaporates.

Nutritional Profile of 200g Raw Red Onion

Beyond just calories, 200g of red onion is packed with a range of essential nutrients. Here is a more detailed look at what a standard 200g portion provides:

Carbohydrates: Approximately 18-20 grams, mostly from simple sugars and fiber.
Fiber: Around 3-4 grams, contributing to digestive health.
Protein: About 2 grams.
Fat: Negligible, less than 0.5 grams.
Vitamins: Rich in Vitamin C, which is a powerful antioxidant, and B vitamins, particularly folate (B9) and B6.
Minerals: Good source of potassium, which is crucial for heart health and fluid balance.

Health Benefits Beyond the Calories

The health benefits of red onions go far beyond their low-calorie nature. The vibrant reddish-purple color of red onions comes from potent antioxidants called anthocyanins. These compounds, along with flavonoids like quercetin, offer significant health advantages.

Here are some of the key health benefits associated with consuming red onions:

Heart Health: Antioxidants in red onions may help reduce blood pressure and cholesterol levels, lowering the risk of heart disease.
Anticancer Properties: Some studies suggest that the compounds in onions, including anthocyanins and fisetin, may inhibit tumor growth.
Blood Sugar Regulation: Eating onions may help regulate blood sugar levels, which is particularly beneficial for individuals with diabetes.
Bone Density: Observational studies have linked regular onion consumption to increased bone density, potentially helping to prevent osteoporosis.
Digestive Health: Red onions are a great source of prebiotics like fructooligosaccharides, which feed beneficial gut bacteria and support overall digestive health.

Cooking Methods and Calorie Impact

Different cooking methods not only affect flavor but also the nutrient profile and overall calorie count of red onions. For example, the heat from cooking can reduce levels of some antioxidants, especially Vitamin C, but can also make other compounds more available to the body.


Cooking Method	Added Ingredients	Approximate Calories (200g)	Notes
Raw	None	~80 kcal	Retains maximum nutrients, sharpest flavor.
Boiled/Steamed	None	~84-88 kcal	Low-calorie, softer texture. Water soluble vitamins may leach.
Sautéed	1 tbsp olive oil (~120 kcal)	~200 kcal	Increases calories significantly. Brings out sweetness.
Caramelized	Oil + sugar (optional)	Highly variable	Can become calorie-dense. Adds deep, sweet flavor.

For those looking to maximize the health benefits and keep the calories low, consuming red onions raw or using minimal fat for cooking is the best approach. They can be added to salads, salsas, and sandwiches for a refreshing, nutrient-rich crunch. For cooked dishes, incorporating roasted or boiled red onions can add depth of flavor without the extra fat.

Conclusion

In summary, 200g of raw red onion contains approximately 80 calories, making it an excellent addition to a healthy diet. This amount can increase depending on how you prepare it, especially with added oils. Beyond their low-calorie count, red onions are a nutritional powerhouse, rich in potent antioxidants, vitamins, and minerals that contribute to heart health, gut health, and more. For more comprehensive nutritional information on onions and other foods, consult authoritative sources like the USDA's FoodData Central or a reputable health website USDA Food and Nutrition Service: Red Onions, Fresh. Incorporating this flavorful and beneficial vegetable into your meals is a simple and delicious way to boost your overall health.

A Quick and Easy Recipe Idea

Quick Pickled Red Onions

Thinly slice one red onion (approx. 200g) and place in a jar.
Heat 1/2 cup white vinegar, 1/2 cup water, 1 tbsp sugar, and 1/2 tsp salt until dissolved.
Pour the hot mixture over the onions in the jar.
Seal and refrigerate for at least 30 minutes. Enjoy on salads, tacos, or sandwiches for a tangy, low-calorie addition.

Frequently Asked Questions

Yes, cooking can change the calorie count. If you add oil or butter, the calories will increase. However, cooking methods like boiling or roasting without added fat will have minimal impact on the calories from the onion itself.

While all onions are healthy, red onions have a higher concentration of certain antioxidants, specifically anthocyanins, which give them their color and additional health benefits.

The primary source of calories in a red onion comes from its carbohydrates, which include both simple sugars and dietary fiber.

Yes, red onions can be beneficial for weight loss. They are low in calories and fat, but high in fiber, which helps promote a feeling of fullness and aids in healthy digestion.

To get the maximum nutritional benefit, particularly for antioxidants and Vitamin C, it is best to eat red onions raw in salads, salsas, or sandwiches, as some compounds can be diminished by heat.

A 200g serving of red onion is comparable to many other low-calorie vegetables. For example, 200g of bell pepper has about 52 calories, while 200g of broccoli has around 68 calories, making the red onion a similarly low-energy option.

Raw red onions contain a negligible amount of fat, typically less than 0.5 grams per 200g serving.