Yellow Onion Calories: Exact Count & Nutrition Facts

A medium yellow onion (approximately 110g) contains 44 calories, with virtually no fat and just 10g of carbohydrates. This complete nutritional breakdown reveals why yellow onions are a smart addition to healthy diets.

Curious about the exact calorie count in your cooking staple? You're not alone. Millions search for onion nutrition facts daily as they track dietary intake or explore healthy cooking options. Understanding the precise nutritional profile of yellow onions helps you make informed choices in meal planning without sacrificing flavor.

Nutritional Profile of Yellow Onions: Beyond Just Calories

Yellow onions serve as a kitchen essential across global cuisines, but their nutritional value often gets overlooked. Let's examine the complete nutritional picture based on data from the USDA FoodData Central.

Nutrient	Amount per 100g	Daily Value %
Calories	40 kcal	2%
Total Fat	0.1g	0%
Carbohydrates	9.3g	3%
Dietary Fiber	1.7g	6%
Sugar	4.2g	-
Protein	1.1g	2%
Vitamin C	7.4mg	8%
Calcium	23mg	2%
Potassium	146mg	3%

This nutritional composition explains why yellow onions remain popular in weight-conscious cooking. Their low calorie density means you can add substantial flavor without significant caloric impact. The fiber content also contributes to feelings of fullness, making them valuable in balanced meal planning.

How Preparation Methods Affect Calorie Content

Many home cooks wonder whether cooking changes onion calories. According to research from the USDA Agricultural Research Service, preparation methods significantly impact the final nutritional profile:

• Raw onions: Maintain their natural 40 calories per 100g profile
• Sautéed onions: Absorb cooking oil, potentially adding 30-50 calories per tablespoon of oil used
• Caramelized onions: Concentrate natural sugars through water evaporation, slightly increasing calories per volume
• Roasted onions: Minimal calorie change when prepared without added fats

For those tracking precise intake, weighing onions before and after cooking provides the most accurate measurement. The water content reduction during cooking means 100g of raw onion yields approximately 70g of cooked onion.

Yellow Onion vs Other Varieties: Nutritional Comparison

While all onions share similar nutritional foundations, subtle differences exist between varieties. The National Center for Biotechnology Information confirms these distinctions:

• Yellow onions: Highest in quercetin (a powerful antioxidant) and slightly higher in calories than white varieties
• White onions: Marginally lower in calories (about 37 per 100g) but contain fewer antioxidants
• Red onions: Similar calorie count to yellow onions but contain anthocyanins (the pigments giving them color)
• Shallots: Slightly higher in calories (46 per 100g) but more concentrated in certain nutrients

These differences, while small, matter for those following strict dietary protocols or seeking specific health benefits from their food choices.

Practical Applications in Healthy Eating

Understanding yellow onion calories becomes valuable when planning meals. Consider these practical applications:

• Add diced raw onions to salads for flavor without significant calorie addition
• Use onions as a flavor base instead of higher-calorie ingredients like bacon or butter
• Roast whole onions as a low-calorie side dish (about 100 calories for two medium onions)
• Blend cooked onions into sauces to enhance flavor while maintaining low calorie counts

Nutrition professionals often recommend yellow onions for those managing weight because they add substantial flavor volume with minimal caloric impact. The natural sweetness that develops when cooking yellow onions also helps reduce the need for added sugars in many recipes.

Common Questions About Onion Nutrition

As a culinary professional working with ingredients daily, I frequently address these nutrition questions from home cooks:

How many calories in a small yellow onion?

A small yellow onion (about 70g) contains approximately 28 calories. This makes them an excellent low-calorie option for adding flavor to dishes without significant caloric impact.

Do yellow onions have carbohydrates?

Yes, yellow onions contain carbohydrates. A medium yellow onion (110g) has about 10g of carbohydrates, including 1.7g of dietary fiber and 4.2g of natural sugars. The majority of these carbs come from beneficial compounds like fructans.

Are yellow onions good for weight loss?

Yellow onions can support weight loss efforts due to their low calorie density and high water content. With only 44 calories per medium onion and 1.7g of fiber, they add volume and flavor to meals while keeping calories low. Their natural sweetness also helps reduce the need for added sugars.

Does cooking yellow onions increase calories?

Cooking yellow onions doesn't increase their inherent calories, but preparation methods affect the final count. Sautéing or caramelizing adds calories if oil or butter is used (about 30-50 calories per teaspoon of oil). Roasting without added fats maintains the original calorie count while concentrating flavors.