Cos lettuce has 17 kcal per 100 g. Another name for romaine — the elongated head with sturdy, crisp leaves. Calories are negligible at salad portions.
About this food
How should I track Lettuce, cos or romaine?
For consistent tracking of Lettuce, cos or romaine, weigh it raw. Cooking method changes both weight and calorie density — steaming barely changes anything, but roasting with oil or frying can double the calories. A systematic review (Whitton et al., Adv Nutr 2022) found vegetables are omitted from food logs 2–85% of the time, often because people assume they are "free" calorically. While most vegetables are indeed low-calorie, the fats added during cooking are not. Log the oil, butter, or dressing separately to keep your tracking accurate.