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5 Reasons you are not Losing Weight While Breastfeeding

Updated: Jun 30, 2022

Why am I not losing weight while breastfeeding?

Ask any new or expecting mom why they plan on breastfeeding, and I guarantee "to lose the baby weight" will be in the top 10. At the same time, ask any seasoned breastfeeding mom if they have managed to lose weight while breastfeeding, and I guarantee you'll hear things like

First I lost weight, then I started gaining!


I just can't get rid of those last 10 pounds!


I always gain weight while breastfeeding!


I don't lose the pregnancy weight until after I wean.

What's the deal? Is it just a myth, that breastfeeding helps us shed the pregnancy pounds? Have we been tricked into thinking Junior will simply suck the calories out of us? Doesn't breastfeeding burns calories? And why can't so many of us lose those last 10 pounds? Is dieting possible while breastfeeding?

Does Breastfeeding Burn Calories?

Breastfeeding does burn calories. How many depends on a few things: Baby's age, how often baby nurses, growth spurts, whether baby nurses exclusively or receives supplemental formula/donor milk, whether baby is on solid foods, and ultimately, how much milk mom produces and how many calories are in each ounce of her milk.

On average, there are 20 calories in each ounce of mature breast milk, but this is just an average and the numbers vary from mom to mom (mostly depending on the fat content of her milk), day to day, hour to hour and even throughout a feeding.

If we take that average of 20 calories per ounce of milk and multiply it by 25 ounces (the average daily milk consumption of an exclusively breast fed 2 to 4 month old baby), we are looking at 500 calories 'burnt' (as in, leaving mom's body) by breastfeeding. You can add a little bit more to that because the body uses up energy ('calories') to make breast milk, too. So, in total, we burn around 550 to 670 calories breastfeeding (about as much as you'd burn during a 45 Minute run!). Most health organizations recommend moms should eat an extra 500 calories while breastfeeding, or 300 calories or so if breast milk is not the only source of nutrition for baby.

(FYI, an evidence-based breastfeeding calorie calculator is available here)

So, many moms DO lose weight while breastfeeding because it does burn a lot of calories - but not all do! The question is: Why???

5 Reasons you may not be Losing Weight Breastfeeding

Reason 1: You Don't eat Enough!

It is the age-old myth: To lose weight, we simply have to eat less - calories, that is. After all, there are about 3500 calories in a pound, so eating 500 calories less per day (500 x 7 = 3500) should make us about a pound lighter each week - right? Wrong.

Our body is smarter than that. Especially while breastfeeding!

It has plenty of ways to save those 500 missing calories elsewhere, especially if it feels we are in it for the long run. If we live on a calorie restricted diet, eventually, our body will think tough times are ahead - better save energy elsewhere! After all, it wants to make sure it can continue making adequate breast milk and even prepare for a possible next pregnancy.

To save energy, it could, for example, turn down our inner furnace, making us feel cold and less able to regulate our body temperature. It could also simply turn down our energy production, making us tired and increasing our need for sleep.

All of this will save those calories you worked so hard to restrict in your diet elsewhere! And yes, long term dieting can also mess with our milk supply - certainly the last outcome we'd want from dieting while breastfeeding! Not eating enough may be the reason you're not losing weight while breastfeeding!

To lose weight: Don't starve your body - nourish your body! Give it everything it needs to be energetic, feel good, and produce nourishing breast milk for your baby - not by eating less of what it wants, but by eating more of what it NEEDS. Try to eat at least every 2 to 3 hours while awake, but make sure WHAT you eat isn't empty calories but loaded with nutrients your body needs. While a small calorie deficit should not affect your milk supply, we need at least 1500 to 1800 calories per day to maintain our milk supply.

Reason 2: You eat too Much!

This point may seem to contradict reason 1, but hear me out. You still have to be in a calorie deficit to lose weight! At first, this seems like an easy task, considering how many calories breastfeeding burns, but remember, eating too little can have the opposite effect - it can slow down your metabolism and decrease your milk supply!

Your body is especially vulnerable to this compensatory mechanism during the first 3 months postpartum, so I don't recommend any type of calorie counting or calorie reduced diets for at least the first 3 months postpartum - until your milk supply is well established!

However, if you are not gradually getting back to your pre-pregnancy weight or are gaining weight several months after giving birth, you may want to look at how many calories you are actually eating. No doubt, breastfeeding makes us super hungry, so it's easy to overshoot our daily calorie requirements!

To lose weight: After 3 months postpartum and once your milk supply is well established, it's generally safe to reduce your calories by around 300 (and no more than 500) calories per day. This should allow for safe and gradual weight loss, without compromising your milk supply or metabolism. Start by using a calorie calculator which includes breastfeeding parameters to get a feel for how many calories your body currently needs. Then you need to get a feel for how many calories you take in. You can either do that by tracking your intake using a calorie tracker app, or follow a breastfeeding meal plan that is already calorie controlled.

Aim for a deficit of around 300 (but no more than 500!) calories per day. It is also a good idea to include 'eucaloric days' once or twice per week, which means you will 'up' your caloric intake to meet your requirements so that your metabolism and milk supply are not affected by a long-term caloric deficit. For example, if your daily calorie needs while breastfeeding are 2500 calories, try to eat around 2200 and no less than 2000 calories per day on most days. Once in a while, include a day where you meet all 2500 calories to keep your metabolism up and the milk flowing! And don't forget to eat a nutrient-dense diet because your nutrient requirements while breastfeeding are still high!

Need help meal planning? Try one of my meal plans, which I developed to specifically meet the unique demands and challenges of breastfeeding and postpartum moms such as their unique calorie and macro needs as well as the need for meals that are easy to prepare and snacks that are quick to grab (because #momlife is busy!).

***Limited time: Use code "SAVE10" for 10% off!***

Reason 3: You are Chronically Stressed

Okay, is there a mom in the world who is not stressed at least at some point during the day? It's unrealistic to think we can actually live stressless lives once we reach motherhood level. Gone are the days we can take showers or use the bathroom in privacy, put our feet up at the end of a work day to enjoy a movie, feast on a candle light dinner with our partner or, god forbid, sleep in on the weekend. Let's face it: Life got a whole lot more stressful with kids.

And I know you've heard about the conundrum: Stress releases cortisol, and elevated cortisol levels can lead to weight gain, especially around the midsection.

But turns out, we all have (and need!) Cortisol for our immune function, to maintain blood glucose and more. It's not necessarily the cortisol itself which causes weight gain, but having high and prolonged levels of it, which happens when we're chronically (not temporarily) stressed. If you are having difficulty losing weight, often crave sugary and fatty foods and gain weight especially around your midsection, you may be chronically stressed.

To lose weight: Find ways to de-stress daily. You'll likely need help with this so your kids are taken care of elsewhere. Whether it is yoga, a bubble bath with soothing music, exercise, aromatherapy or simply going for a quiet walk by yourself, find out what helps YOU push the re-set button. And make it a daily priority!

Reason 4: You are Less Active

I know what you're thinking: This doesn't apply to me. I run around ALL day, picking up toys, chasing after the kids, running errands... I am WAY more active than before I had kids. But is this true? Are you really more active, or just busier than before you had kids? Speaking for myself, I know I suddenly spent a lot of time on the couch to nurse. The fast-paced long walks I used to take with my dog also turned into slow-paced strolls around the block with a 5 and 2 year old in tow. Errands I take with my kids sure seem strenuous and I'm exhausted at the end of the day, but, quite frankly, I didn't do much exercise by driving in a car and sitting in waiting rooms.

Are you really more active, or just busier than before?

To lose weight: Every little activity counts! You don't have to spend hours at the gym - making a conscious effort to increase your physical activity little by little will gradually increase your strength and help you lose weight. Walk or jog around the playground while you're there, dance with your kids as a means to wake up in the morning and choose weekend activities which include walking, biking or hiking more often.

Reason 5: It's Your Hormones!

You knew it - I knew it. There is a physical reason some breastfeeding moms have a hard time losing weight. Yes, it may be your hormones.

Prolactin, to be exact. It is the main hormone involved in the production of breast milk, released every time your baby latches. And it wants to make sure we're not getting too skinny! Studies have shown, (non breastfeeding) people with high prolactin levels often gain weight, feel tired and have less energy. Obviously, as breastfeeding moms we have more prolactin than the average person - about 10 times as much. One proposed mechanism through which Prolactin keeps us from losing weight is through the suppression of Adiponectin, another hormone which does the opposite: it promotes a faster metabolism, gives us energy and helps with the break down of fat.

Adiponectin is definitely a hormone we want more of, but Prolactin is also necessary for milk production! It seems, we're in a conundrum... No worries, there are ways to increase Adiponectin naturally, without negatively affecting your milk supply! Studies have shown that 1) moderate exercise, 2) daily fish oil intake and 3) a diet high in fiber can increase adiponectin levels significantly!

To lose weight: Make fruits and vegetables the main part of your diet and replace all refined grains with whole grains to increase your fiber intake. The plate method for breastfeeding moms is a great reminder to make at least half of every meal fruits and vegetables. Also include 2 or 3 servings of low-mercury salt water fish (salmon, herring etc.) in your diet per week to get some of those healthy fats - and limit unhealthy fats. That, along with some moderate exercise, will help your body burn fat more effectively and increase your adiponectin levels while maintaining your milk supply!

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