What's the deal with breastfeeding and weight loss?

We take a look at some of the conceptions, and misconceptions, of breastfeeding and weight loss.
Written by
Rachael Crouch
Reviewed by
Last updated on
January 19, 2024
min read
What's The Deal With Breastfeeding And Weight Loss | Kin Fertility
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If you didn't gain much weight during pregnancy, that's OK. If you did, that's also OK. Pregnancy is extremely demanding of your body and weight gain while growing your baby is an essential aspect.

If you gained more pregnancy weight than you would have liked to, then you may be looking forward to breastfeeding. Breastfeeding has been widely touted as the key to weight loss post-pregnancy, and many people can attest to experiencing weight loss once they start [1].

But this isn't necessarily true, and definitely not for all people. There is an ongoing and persistent belief that breastfeeding will make you lose weight without any effort at all.

If this seems too good to be true — losing all your pregnancy weight within months of breastfeeding — it probably is. Yes, you may lose some weight, but your body still needs a lot of its important nutrients to survive and thrive with your new baby.

Your body is burning calories simply through the act of breastfeeding. But consuming postpartum-supporting nutrients is extremely important for your milk supply and your overall well being.

This article will take a look at some of the conceptions, and misconceptions, of breastfeeding and weight loss.

Do you need to increase your calorie intake when breastfeeding?

Yes, breastfeeding mothers DO need to increase their calorie intake! In fact, an additional 450 to 500 calories are recommended for breastfeeding mothers [2].

Things like your age, weight, BMI and other health issues should also be factored in when landing on how many calories you should be consuming while breastfeeding.

It's not uncommon to feel hungrier than usual while breastfeeding: your body is a provider for your baby, so you must replenish those lost calories where you can. It's burning energy at a faster rate than what you were previously burning.

If you don't consume those extra calories, your body's stores of fat, carbohydrates, protein and other nutrients are used to maintain high-quality milk for your baby, depleting you even further.

If you are a breastfeeding mum, you will also notice how much thirstier you become as this precious fluid leaves your body and goes to your baby's belly, providing them with all the nutrients and antibodies they need to help them grow, develop and fight off infections [3].

As you continue to feed, your baby will be drawing on your body's stores of nutrients through your milk. And, if you are low in critical nutrients, your baby will take from your own supplies, leaving you low in energy and with low immunity [4].

Just as your thirst increases while you breastfeed, this can also deplete your body’s stores of certain fundamental nutrients including zinc, vitamin D, DHA and B vitamins among others. This is especially true if you're already deficient in these areas.

Of course, the fourth trimester is a difficult time to be thinking about your diet; we know your hands are full. This is why postpartum supplements exist, to help you keep your nutrient levels up while you manage this new phase of your life.

Kin's Postnatal Vitamins are designed to support the nutritional needs of new mothers for up to six months after birth and while breastfeeding. The postpartum period is incredibly demanding and postpartum depletion is an incredibly common experience.

This is why Kin's Postnatal is formulated with 18 essential micronutrients in optimal dosages to support your daily energy levels, immune function and red blood cell formation to assist with blood health and growth. It also aids with brain health, helping you to feel supported and alert as well as supporting hair follicles to help with postpartum hair loss and keep you feeling like you.

While breastfeeding can strip you of important nutrients, eating nourishing foods, staying hydrated and taking postnatal supplements designed to support you nutritionally can help you feel your best at a time of great energy expenditure and very little sleep.

Does breastfeeding make you lose weight?

Breastfeeding does indeed make you lose weight, in that breastfeeding actively burns calories. But the reality of this is quite different.

One of the biggest misconceptions about breastfeeding is that it’s going to make the weight you gained during pregnancy just fall off without any effort. But that’s certainly not everyone’s experience. Breastfeeding mums often feel very hungry and may eat more.

If you are eating processed foods, or sugary foods for a burst of much-needed energy, especially if you're in a haze of sleep deprivation, those 500 calories you're burning through breastfeeding will come back on easily.

If you are in a calorie deficit, though, you will lose weight. But generally, the amount breastfeeding mothers tend to lose is fairly small.

One analysis showed that the impact of breastfeeding had a very small effect on women's weight loss while breastfeeding. Of six observational studies where women's postpartum weight change was measured, only one showed an association with breastfeeding [5].

And, the weight actually lost was minimal: breastfeeding mums had lost between half a kilo and two kilos more weight than mums who didn’t breastfeed.

This is true for another study in the USA where women who breastfed exclusively for the first three months had lost just under two kilos [5]. Some weight loss will occur no matter what after you give birth, and the loss will be gradual as your body adjusts to a postpartum state.

For one thing, you're losing a small baby that's been waiting to pop out!

Secondly, the retention of extra blood and water you accumulated to support the baby through pregnancy (a whopping 50 per cent more than normal in fact), is gradually released through sweating and urination in the weeks after birth.

You can speed up the fluid loss by staying hydrated, doing light exercise (once you've been cleared to exercise again by your GP), reducing your salt intake and even with some gentle massage.

Essentially, lactating people burn more calories each day and this, combined with fluid loss, a healthy, balanced diet and some light exercise, will all contribute to postpartum weight loss.

Can I go on a diet while breastfeeding?

It's certainly understandable if you're keen to get back to your pre-pregnancy size after giving birth. But, dieting can get in the way of milk production: there is a reason your body is asking for more calories. It's to make a strong supply of nutritious milk for your new baby.

Drastically cutting calories and following fad diets means you probably aren't receiving a steady balance of nutrients [6].

Instead, it's really important to incorporate gentle exercise into your day and follow a balanced diet to support your weight loss. Also, it's likely you are experiencing sleep deprivation, so pushing yourself right now with vigorous exercise is also not recommended from a physical safety perspective.

Essentially, breastfeeding is not a time to lose weight quickly [7]. Losing pregnancy weight is often on people's minds after they give birth, but rushing into diets, especially crash or fad diets, can be detrimental to your body's recovery and your milk production.

Breastfeeding parents need to eat a wide variety of nutrient-dense foods to cope with the demands of breastfeeding, so maternal nutrition should be at the front and centre of any diet you start.

What are the best foods to eat for milk supply?

It is widely known that even mothers who have given birth in famine, with little to no food available, will still be able to produce nutritious breast milk full of fat, proteins, carbohydrates and macronutrients necessary to help their babies grow.

There is a lot of anecdotal evidence out there about certain foods boosting milk supply including oats, flax seeds, fenugreek and garlic. But, there is little in the way of high-quality research out there to say for sure whether eating a specific food can really increase milk supply.

Instead, there is plenty of scientific evidence to suggest the following things will keep your milk supply strong and continuing:

  • Feed, feed and feed: The more you get breast milk out of the boob and into the baby, whether it's through breastfeeding or pumping and bottle feeding, the more your body will produce milk [8]. Your body is amazing: milk supply will adapt to the needs of your baby, so by feeding and pumping you are telling your body to keep up with that lovely, nutritious breast milk.
  • Enjoy skin-to-skin contact: Holding your baby and feeling its skin on yours can help increase your milk supply as it triggers the production of prolactin and oxytocin [9]. Both of these hormones help your body to make and release breastmilk.
  • Don't stress: This might seem like a big ask for new mothers, but stress can be a major impediment to milk production [10]. Remove stressful events, people and things from your life as much as you can and ask for help wherever you can. Losing weight can be stressful, and if it is, ensure your milk production is well established before you even think about tackling weight loss.

Why do some people experience weight loss when breastfeeding and others don't?

As we have said before, some people will experience weight loss while breastfeeding, and others will actually experience weight gain.

Your weight is the culmination of not just what you eat or how you move, but your metabolism, your BMI, your genetics and many other physical and environmental factors that you live with.

We also have to take into account the high levels of prolactin breastfeeding mothers are producing. Prolactin is a critical hormone needed for milk production but it also exists in men and non-breastfeeding people.

Studies have shown that non-breastfeeding people with high levels of prolactin often gain weight, feel tired and have less energy [11]. And, as breastfeeding people have higher than usual levels of prolactin, this is going to affect their weight too.

Do I need to drink more water while breastfeeding?

Yes. Not only does breastfeeding make you feel hungrier, but it will also make you thirsty.

The oxytocin released when your baby attaches for a feed also makes us thirsty. You will need to drink around 16 cups of water a day to keep up with your body's water needs [12].

Breastfeeding weight loss in a nutshell

Infant feeding is hard and will be on your mind a lot. And, going back to your pre-pregnancy weight might seem like it's on the horizon now that you're no longer pregnant.

Eating nutritious foods and engaging in moderate exercise is the best thing you can do for your body right now. Losing weight gained in pregnancy is a good thing to do, but not at the expense of a balanced diet.

Here's a quick summary of what we've covered:

  • Have two to three serves of protein per day (including lean meat, chicken, fish, eggs, cow's milk, beans, nuts and seeds). If you're following a vegetarian or vegan diet, ensure you're consuming all the nutrients and protein necessary.
  • Enjoy at least three servings of vegetables, including green, orange and yellow vegetables per day. Have at least two serves of colourful fruit, too.
  • Eat carbs (especially whole grains including whole wheat, pasta, rice and oats).
  • Drink water and stay hydrated.
  • If you don't eat animal products, ensure your diet includes other sources of B12, zinc, iodine and iron.
  • Take a postpartum supplement to make sure you are getting all the nutrients you need.
  • Do not lose weight quickly. Try your best to maintain a healthy weight, and think about weight reduction after the newborn period. Give yourself time. Avoid crash or fad diets while breastfeeding.
  • Wait at least three months for your milk supply to be firmly established before actively trying to lose weight.
  • Don't worry! Gradual weight loss is the best way to go about losing weight, for both you and your baby. A mother's diet should be grounded in clinical nutrition. Even if you gain weight while breastfeeding, it doesn't matter: you will get to where you need to be soon enough.
  • Ask for help. Kin's Breastfeeding Essentials kit is the go-to for all your breastfeeding needs as you start your breastfeeding journey. You can also talk to a lactation consultant about any other issues you have about breast milk.

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