by Anni Laas & Maarja Lember 

Breastfeeding has several benefits for the baby and the mother. It is highly recommended that women, who have gone through weight loss surgery, should breastfeed their babies. However, mothers will need to be extra careful to make sure that they are eating a healthy and varied diet. A healthy diet will help to ensure that the baby will get all the required nutrients to support his or her optimal growth and to prevent any nutritional deficiencies of the baby and the mother herself.

Paediatricians strongly recommend exclusive breastfeeding for the first six months and that breastfeeding continues for at least 12 months. Inform your baby’s paediatrician of your weight loss surgery, as more frequent checks, may be needed to monitor for growth and developmental milestones and to identify any possible nutritional problems as early as possible.

Macronutrients recommendations

Breastfeeding increases women’s daily calorie requirements 300-500 kilocalories (kcal) above the recommended intake for weight maintenance. On average the energy intake should be around 1800 to 2200 kcal per day. Energy intake should not be below 1500 kcal per day as too low energy intake can lessen milk production.

Protein intake should be around 60-70 grams per day. There should be 4-6 small meals with a protein source at every meal. Good sources of protein are lean meats, oily fish and low-fat milk products. Aim for three servings of milk products every day, as this will help to ensure adequate calcium intake, that is needed for baby’s bones and teeth.

Breastfeeding women should eat fish 2-3 servings per week. Choose fish that is low in mercury and preferably oily fish as this is important sources of omega-3 fatty acids, that is necessary for baby’s brain development. Good examples are salmon, sardines, herring, freshwater trout and Atlantic mackerel. Other good sources of omega-3 fatty acids are walnuts, flaxseeds, chia seeds and oils made from these seeds.

For carbohydrates prefer vegetables, fruits and wholegrain products as these are an important source of different vitamins and minerals. Try to limit added sugar intake, as sugary foods are often low in different nutrients and high in calories, which can hinder the post-pregnancy weight loss.


During breastfeeding, you should drink 1800-2300 ml fluids per day. Fluids include water, tea, diluted juices, smoothies, but not coffee. Drinks that contain caffeine (coffee, tea, cola and energy drinks) may cause your baby to become irritable if you drink them in large amounts.


Weight loss surgery, especially gastric bypass, affects the absorption of vitamins and minerals.  After weight loss surgery there is a higher risk for iron, vitamin B12, calcium, folate, zinc, vitamin D and protein deficiencies. While breastfeeding, it is advisable to ask your doctor to check your blood every three months to see that you are absorbing enough vitamins and minerals (especially vitamin B12, iron, vitamin D) and protein.

Anaemia is common during pregnancy and breastfeeding as there is a decreased absorption of iron and iron stores are utilized for the growing foetus. Maternal anaemia is associated with poorer infant physical and emotional development and increased risk of maternal postpartum depression. The most feared risk for the baby has to do with B12 vitamin.

A full-term infant of a well-nourished mother will be born with a body store of vitamin B12. This store is sufficient to meet the baby’s needs for the first 8 months. If the mother is not vitamin B12 deficient herself, then her milk is an excellent source of vitamin B12. However, when the mother is deficient of vitamin B12 then the baby will have a low store of vitamin B12 at birth and this store will not improve as the breast milk is also lower in vitamin B12. Breastfed infants may develop clinical signs of vitamin B12 deficiency before their mothers do.

Signs and symptoms of B12 deficiancy

Signs and symptoms of vitamin B12 deficiency in infants include vomiting, lethargy, anaemia, failure to thrive, hypotonia (low muscle tone), and delays in reaching developmental milestones. Vitamin B12 deficiency may develop in the breastfed infant by 2 – 6 months of age but may not be clinically apparent until 6 – 12 months.

To prevent any possible nutritional problems mothers should take their supplements daily to ensure that the breastmilk is nutritionally adequate. It is recommended to take every day:

  • General multivitamin: one manufacture’s dose twice a day. It is advisable to use breastfeeding specific multivitamin.
  • Iron: 60-100mg as iron fumarate
  • Calcium: 1200-1500 mg of calcium citrate per day, in divided doses of 500-600 mg. To ensure adequate absorption of iron and calcium then do not take iron and calcium supplements together.
  • Vitamin D: 3000-4000 IU vitamin D3
  • Vitamin B12: 1000mcg per day orally or 1000mcg as an intramuscular injection every 3 months.

If you are taking a bariatric specific multivitamin, then ask your bariatric dietitian or nurse if the supplement is suitable and do you need to take any extra vitamins or minerals.

Regarding your baby, then breast milk has a sufficient amount of all vitamins except vitamin D and vitamin K. Therefore, breastfed babies need vitamin D drops from birth. Please check with your baby’s doctor, about which type and how much vitamin D you need to give.

Weight loss after pregnancy

Many women who have had weight loss surgery are fearful that they will not lose the weight gained during pregnancy. While breastfeeding you should focus on the balance and variety of your diet and not on weight loss. Nutritional intake should be adequate to promote and sustain milk production and should be enough to prevent any fast weight loss after pregnancy.

Weight loss up to 0.5 kilograms per week has been shown to not effect milk production. It is important to know that restricting energy under recommended levels may cause insufficient milk syndrome and should be avoided. Insufficient milk syndrome might also be caused by retained placenta, delayed lactogenesis, infrequent feeding or baby’s problems with suckling and swallowing.

In certain cases, polycystic ovary syndrome (PCOS), insulin resistance, or thyroid problems can also decrease milk production. If you have any of these conditions, then speak with your doctor.

Tips for successful breastfeeding

Mothers can use different techniques for lactation success. For example, increasing skin to skin contact and give frequent breastfeeds especially in the first 24 hours to avoid delayed lactogenesis. Nipple massage makes the engorged breasts softer, which may help baby to latch on more easily.

Elongated breast tissue may require support under the breast through rolled towels or pillows or by adjusting nurturing position to be laid-back, as this will help the baby grasp more breast tissue. Mothers should meet with a Lactation Consultant to ensure that adequate milk is being produced, the infant is able to extricate milk from the breast and is growing appropriately.

To summarize: 

  • Breastfeeding after weight loss surgery is highly recommended.
  • Eat 5 small meals per day. Meals should consist of protein source, vegetables and wholegrains.
  • Limiting calories too much can decrease breast milk production.
  • Inform your baby’s paediatrician of your weight loss surgery, as more frequent baby checks may be needed to monitor for growth and developmental milestones and to identify any possible nutritional problems as early as possible.
  • Take vitamin and mineral supplements to ensure the nutritional adequacy of breast milk.
  • While breastfeeding, it is advisable to ask your doctor to check your blood every three months to see that you are absorbing enough vitamins, minerals and protein.



Slater, C., et al. Nutrition in Pregnancy Following Bariatric Surgery. Nutrients. doi:10.3390/nu9121338 Harreiter, J. et al. (2018). Management of Pregnant Women after Bariatric Surgery. Journal of Obesity. doi: 10.1155/2018/4587064