Breastfeeding fact: breastfeeding helps you burn calories because it takes calories to make calories. We need on average an extra 300-500 calories per day in our diet because our bodies need approximately 20 calories to make an ounce of breast milk. Not everyone will lose weight while breastfeeding. It depends on and how many calories they take in and how their body uses those calories related to their individual milk production. Food choices, hydration, activity levels, and genetics also all play a role on weight loss while breastfeeding