Why many breastfeeding mothers lose weight

Dear Doctors: I’m breastfeeding my 4-month-old son, and I’ve lost some weight. I’m naturally thin, but my sister thinks my baby is not getting the nutrients he needs. The pediatrician says my son is doing great, but I’m worried. Do I need to switch to formula?

Answer: When a new mom is in good health and eating a balanced and well-rounded diet, her breast milk has everything a baby needs to grow and thrive.

Breast milk not only contains fat, protein and carbohydrates but also vitamins and minerals and water for hydration and a range of important bioactive compounds that help train and strengthen the baby’s developing immune system and aid in brain development.

Breast milk is easily digested and absorbed. And the act of breastfeeding can be an important part of bonding between mother and infant.

Your pediatrician says your baby is doing well and meeting growth guidelines for his age. That means your breast milk is doing its job. Unless your pediatrician suggests it, there’s no need to switch to formula.

The recommendation from the American Academy of Pediatrics is, when possible, to exclusively breastfeed until the baby is four to six months old. At that point, switch to a mix of breastfeeding and appropriate solid foods.

On your own weight loss while breastfeeding, it’s not unusual. Women who breastfeed burn an additional 500 to 700 calories a day, which can lead to weight loss. Since you are already thin and are continuing to lose weight, adjust your diet to make up for the calories your body is using to produce milk.

As you focus on calorie-rich foods and meals, stay within the parameters of a healthy diet. Your baby is eating what you’re eating. Include plenty of high-quality protein, fresh fruits and vegetables, leafy greens and healthful oils. Choose high-value snacks like nuts, seeds, yogurt and nut butters.

Occasional “cheats” are fine, but try not to make highly processed foods a regular part of your diet.

And don’t forget to stay hydrated. If you maintain an increased caloric intake and still lose weight while breastfeeding, check with your obstetrician.

A new baby to care for is already a challenge. Having a family member offer opinions that adversely affect your comfort and confidence isn’t helpful. You might consider bringing your sister along to your baby’s next visit to the pediatrician.

You can broach the question of your weight and the baby’s nutritional needs, and hopefully the doctor can ease your minds.

Dr. Eve Glazier and Dr. Elizabeth Ko are internists at UCLA Health.