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.

take a look at this link to find out a host of healthy and low calorie foods http://www.mayoclinic.org/healthy-lifestyle/weight-loss/multimedia/low-calorie-foods/sls-20076175 but make sure you are eating healthy when you are breastfeeding. trust me, you will be able to reduce your weight once you complete breastfeeding. just stay away from fried and greasy foods as well as processed foods :)