What are some low-calorie nutritious foods that are a must in a breastfeeding mother’s diet?

one thing that i would like to tell you is that make sure you are eating healthy, and are not taking less nutrients. since you asked for low calorie foods, you could go for cucumbers, plums, celery, radish, strawberries, grapefruit, blackberries, wheat bran, popcorn, chicken breast, lentils, egg whites, nonfat yogurt without flavour, unsweetened almond milk, broccoli, cabbage, lettuce, beets, cauliflower, tomatoes, turnips, spinach, pumpkins and carrots.