White Onion Calories: Exact Count & Nutritional Facts

A medium white onion (approximately 148g) contains just 64 calories, with 100g providing only 43 calories. This makes white onions an excellent low-calorie ingredient for weight management and healthy eating plans while delivering essential nutrients like vitamin C and dietary fiber.

Discover exactly how white onions fit into your nutritional goals with this science-backed guide. Whether you're meal prepping, tracking macros, or simply curious about this kitchen staple, you'll get precise calorie information plus practical tips for maximizing flavor without compromising your health objectives.

Nutritional Profile of White Onions: Beyond Just Calories

White onions serve as a nutritional powerhouse despite their low-calorie count. According to the USDA FoodData Central database, a standard medium white onion (148g) delivers:

Nutrient	Amount per Medium Onion (148g)	Amount per 100g	Daily Value %
Calories	64	43	3%
Total Carbohydrates	14.9g	10.1g	5%
Dietary Fiber	2.7g	1.8g	10%
Vitamin C	11.8mg	7.9mg	13%
Vitamin B6	0.2mg	0.1mg	12%
Folate	19.2mcg	13mcg	5%

These values come directly from the USDA's National Nutrient Database for Standard Reference, the most current and comprehensive nutritional database maintained by the United States Department of Agriculture (fdc.nal.usda.gov). The database undergoes regular updates based on laboratory analysis of food samples, ensuring accuracy for dietary planning.

White Onion vs. Other Varieties: Nutritional Comparison

While all onion varieties share similar nutritional profiles, subtle differences exist that might influence your cooking choices:

• White onions contain slightly more vitamin C than yellow onions (11.8mg vs 10.2mg per medium onion)
• Red onions provide additional anthocyanins, the antioxidants responsible for their purple color
• Yellow onions have marginally higher carbohydrate content but similar calorie counts
• Shallots offer more nutrients per serving but come with higher calorie density

Research published in the Journal of Agricultural and Food Chemistry confirms that white onions maintain their nutritional integrity better during storage compared to other varieties, preserving their vitamin C content for longer periods when kept in cool, dark conditions.

Practical Calorie Management with White Onions

White onions deliver maximum flavor impact with minimal caloric cost, making them ideal for various dietary approaches:

For Weight Management

With just 43 calories per 100g, white onions add substantial volume and flavor to meals without significantly impacting your daily calorie budget. A cup of chopped white onion (160g) contains only 69 calories, providing 3.6g of fiber to promote satiety.

Culinary Applications by Calorie Budget

• Under 50 calories: Raw in salads, salsas, or as a garnish
• 50-100 calories: Lightly sautéed with minimal oil for sandwiches or wraps
• 100+ calories: Caramelized with healthy fats like olive oil for richer dishes

Health Benefits Beyond Calorie Count

White onions contribute to overall health through multiple mechanisms:

• Antioxidant properties: Contain quercetin, which may help reduce inflammation
• Heart health: Organosulfur compounds may support healthy blood pressure levels
• Digestive benefits: Prebiotic fiber feeds beneficial gut bacteria
• Blood sugar management: Low glycemic index (10) makes them suitable for diabetes-friendly meals

The American Journal of Clinical Nutrition published research showing that regular onion consumption correlates with improved cardiovascular markers, particularly when consumed raw to preserve heat-sensitive compounds.

Maximizing Nutritional Value: Selection and Storage

Follow these evidence-based practices to get the most nutritional benefit from white onions:

• Selection: Choose firm bulbs with dry, papery skins and no soft spots
• Storage: Keep in a cool, dark place with good air circulation (not refrigerated)
• Preparation: Leave outer layers intact until ready to use to preserve nutrients
• Cutting technique: Slice rather than dice to minimize nutrient loss during cooking

Studies from the University of California's Agriculture and Natural Resources department demonstrate that white onions retain up to 20% more vitamin C when stored at room temperature compared to refrigeration, contrary to common practice.

Common Questions About White Onion Nutrition

Understanding the practical implications of white onion nutrition helps you make informed dietary choices: