Spinach vs Onion: Nutrition Comparison
Which is healthier? Compare calories, protein, carbs, and more
Complete side-by-side nutrition comparison per 100g serving | Updated 2026
Which is Healthier?
Spinach is generally healthier
Spinach comes out ahead in this comparison, winning in 4 out of 5 key nutritional categories. It has fewer calories (23 vs 40), more protein (2.7g vs 1.1g), more fiber (2.2g vs 1.7g), less sugar (0.4g vs 4.2g), making it the better choice for most health goals.
Quick Summary
Fewer Calories
Spinach
23 kcal
More Protein
Spinach
2.7g
More Fiber
Spinach
2.2g
Less Sugar
Spinach
0.4g
Visual Comparison
Side-by-Side Nutrition Table
Serving Size Comparison
All values above are per 100g. Here's how they compare in common serving sizes:
Spinach
Onion
Diet Compatibility
Spinach
Onion
When to Choose Spinach
- ✓Lower in calories (23 vs 40)
- ✓Higher in protein (2.7g vs 1.1g)
- ✓More fiber (2.2g vs 1.7g)
- ✓Lower in carbs (4g vs 9g)
- ✓Less sugar (0.4g vs 4.2g)
Common Uses
When to Choose Onion
- ✓Lower sodium (4mg vs 79mg)
Common Uses
Spinach vs Onion: Nutritional Analysis
Onion is more calorie-dense at 40 calories per 100g compared to 23 for Spinach, a difference of 17 calories. On the protein front, Spinach delivers more with 2.7g per 100g versus 1.1g, which matters for muscle maintenance, satiety, and overall metabolic health. These differences become meaningful when you consider how each food fits into your daily dietary pattern rather than looking at any single nutrient in isolation.
Macronutrient Breakdown
The macronutrient profiles of Spinach and Onion tell different nutritional stories. Spinach provides 4g of carbohydrates, 0.4g of fat, and 2.2g of fiber per 100g, while Onion contains 9g carbs, 0.1g fat, and 1.7g fiber. The higher fiber content in Spinach supports digestive health, helps regulate blood sugar after meals, and contributes to longer-lasting satiety. Sugar content also differs: Spinach contains 0.4g while Onion has 4.2g per 100g. Lower sugar options are generally preferable for blood sugar management and dental health.
Key Takeaways
- For weight management: Spinach is the lower-calorie choice at 23 cal/100g, making it more suitable for calorie-controlled diets.
- For muscle building: Spinach provides more protein (2.7g/100g), supporting muscle repair and growth.
- For sustained energy: Spinach offers more fiber (2.2g/100g), which slows digestion and provides steadier energy release.
- Overall: Neither food is universally "better" than the other. The right choice depends on your specific nutritional goals, meal context, and dietary preferences. Both can play a role in a balanced diet.
Frequently Asked Questions
Which has more calories, Spinach or Onion?
Onion has more calories with 40 kcal per 100g, compared to Spinach with 23 kcal. That's a difference of 17 calories per 100g serving.
Is Spinach healthier than Onion?
Based on our nutritional analysis, Spinach is generally the healthier choice, winning in 4 out of 5 key nutritional categories. Spinach has 23 calories, 2.7g protein, and 2.2g fiber per 100g. However, the best choice depends on your specific dietary goals.
What is the protein difference between Spinach and Onion?
Spinach has more protein with 2.7g per 100g, compared to Onion with 1.1g. Spinach provides 1.6g more protein per 100g serving.
Which is better for weight loss, Spinach or Onion?
For weight loss, Spinach is the better choice with only 23 calories per 100g compared to 40 calories in Onion. Spinach also offers 2.2g of fiber per 100g, which helps you feel fuller longer.
Does Spinach or Onion have fewer carbs?
Spinach has fewer carbs with 4g per 100g, compared to Onion with 9g. If you're following a low-carb diet, Spinach is the better option with 5.0g fewer carbohydrates.
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About Our Data
All nutrition data in this comparison is sourced from the USDA FoodData Central, the official food composition database maintained by the U.S. Department of Agriculture. Values are based on 100g servings for accurate comparison.
Health Disclaimer: This comparison is for informational purposes only and is not intended as medical or dietary advice. Nutritional needs vary by individual. The best food choice depends on your personal health goals, dietary requirements, and preferences. Consult a healthcare provider or registered dietitian for personalized nutrition guidance.