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First Years Jan 17, 2021
5 Minutes

Breastfeeding, nutrient depletion and weightloss: fact or fiction?

It has long been argued that one of the perks of breastfeeding is postpartum weightloss. However, the science suggests it isnt actually that simple. We take a look at the reality and even more crucially the nutrients we have to watch that can get particularly depleted during breastfeeding…. 

13 kgs of fat burnt in 6 months?! What the science really says about breastfeeding and weight loss: 

Producing milk takes a lot of energy. Approximately 595kcal/day during the first two months of exclusive breastfeeding rising to 670kcal/day between three to six months (1). So, in theory all else being equal it should = significant potential weight loss. 

In fact, if everything else remained the same, six months of exclusive breastfeeding would burn a whopping 117,390 kcals. That would = mobilisation of approximately 13 kilos of body fat!

That is a very large amount and not typically the weight loss we see six months postpartum. So, something else is likely going on…

All about hormones: the reason you’re always hungry when you’re breastfeeding: 

The power of hormones does not end in pregnancy. Breastfeeding also causes powerful hormonal fluctuations. Specifically related to the hormone Prolactin which is responsible for milk production. 

Guess what: Prolactin is also associated with increased appetite and food intake. So, chances are: breastfeeding makes us hungrier and more likely to take in more food/energy to offset the energy requirements of milk production. Clever stuff. 

Prolactin, breastfeeding and weight loss (or not!). Timing is key: 

We know that in the first few months of lactation maternal serum prolactin concentrations are at their highest. These tend to drop following the initial surge, particularly as we approach four-six months postpartum when babies start to move towards solid food. 

The research correlates: it takes around four to six months for breastfeeding associated weightloss. Even then it is not for everyone nor is it necessarily a lot…  

One meta analysis (review of many studies) showed that on average there were no significant differences between breastfeeding and non breastfeeding women in terms of weightloss in the early months. Even following that, from months four to six of exclusive breastfeeding it is at most a couple of kilos. (1) 

Breastfeeding often also requires a lot of time sitting down: 

So, in reality we don’t tend to see massive weightloss associated with breastfeeding. It also likely takes at least four months to kick in. This is likely because of a variety of factors:

  • Prolactin rising initially causing us to want to eat more to meet the energy requirements of breastfeeding. In fact it is recommended to eat 500 extra calories/day to ensure good milk supply. 
  • Prolactin then peaks and starts to drop after the first couple of months. 
  • Some people appear to be more sensitive to prolactin than others. 
  • It could also of course be because exclusive breastfeeding requires a lot of time sitting down! Less physical activity also reduces how many calories we burn.
  • Whether you are exclusively feeding with breast milk also makes a difference. 

One certainty: breast-feeding does require a lot of nutrients: here are the ones that are most used/vulnerable to depletion: 

So, the weightloss aspect of breastfeeding is not a slam dunk. It varies from person to person and extent that you do it. It also appears to relate to an individual’s sensitivity and reaction to the hormone prolactin. However, one thing we do know is that the nutrient demands from breastfeeding are very real. Particularly when it comes to the B vitamins, Vitamin A, Copper, Selenium, Iodine and DHA/EPA. 

Some nutrients are required up to 90% more than normal during breastfeeding: 

Here are some of the increased demands breastfeeding puts on our recommended daily intake: (1)

  • 17% increase for Vitamin B12
  • 86% increase for Vitamin A
  • 50% reduced demand for iron 
  • 27-93% increased demand for copper/selenium and Iodine
  • +50% increase in demand for Vitamin C and Zinc. 

DHA/EPA – also known as Omega 3s. We know that these are particularly important for proper development of the brain and immune system. Click here for much more. 

Now more than ever we need to ensure our bodies are nutritionally well supported: 

Postpartum weight loss (or lack of!) can be frustrating. However, the above stats show the huge nutrient demand breastfeeding requires. Both in terms of calories and micronutrients. The key is not calorie restriction but instead focusing on supporting our bodies with high quality, whole foods. All the research points to a Mediterranean diet as the best bet. Full of healthy fats, high quality proteins (principally plant and fish with occasional meat), grains and lots of fresh fruit and vegetables. Empty calories won’t help us. 

Nutritional support for our postpartum bodies: breastfeeding or not: 

Pregnancy takes a huge toll on the body. Adequate nutrition is required not only for breastfeeding but also for physical and mental recovery. In fact, good nutritional support has even been shown to reduce the chances of postpartum depression and anxiety. Click here for the eight nutrients you need to ensure you/your baby get enough of. 

Supporting the microbiome: 

One of the most powerful elements of breastmilk is the density of pro and prebiotics that build a baby’s own microbial landscape. We now know this is key for brain development, immunity hormones and even mental health. Click here for much more of the science. 

Ensuring your own gut health is in tip top condition is a great way of promoting this. Once again a Mediterranean diet is a great start. Avoiding processed foods, refined sugars, alcohol etc. Focusing on probiotic foods like kefir, sauerkraut and yogurt. Prebiotic foods include artichokes, bananas, berries, garlic, flaxseed and asparagus. Click here for much more. 

Specific exercise: regular resistance training (once you have sign off from your doctor) has also been shown to be a powerful tool to improve your milk. True story! For the full run down click here. 


This article is for informational purposes only. This article is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. The information on this website has been developed following years of personal research and from referenced and sourced medical research. Before making any changes we strongly recommend you consult a healthcare professional before you begin.




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