Verdict
Per drained can, tuna in water has 139 kcal vs 238 kcal for tuna in oil — almost 100 kcal less — with 1.2 g of fat vs 9.8 g. Even well drained, the tuna absorbs part of the oil. Protein is similar (30.6 g vs 34.9 g). If you count calories, water is the obvious pick; oil can fit when you need more calories in the day.
When to choose Tuna in water
- You're in a deficit and want almost pure protein.
- You'll season it yourself (a measured drizzle of olive oil gives more flavor for fewer calories).
When to choose Tuna in oil
- You're bulking and the extra calories help.
- You prefer the softer texture — and drain it well before using.
Values per 100 g of ready-to-eat food, from the Brazilian Food Composition Table (TACO) and USDA FoodData Central. They vary by brand, cut and preparation. Educational estimates, not individual nutrition advice.