not losing weight breastfeeding

3 Reasons You’re Not Losing Weight Breastfeeding (What To Do Instead)

3 Reasons You’re Not Losing Weight Breastfeeding (What To Do Instead)

Let me guess.

You just had a baby. You're exhausted, sore, and anxious to get back to feeling like yourself again. But despite what you've been promised, you're not losing weight breastfeeding.

Maybe, rather than losing, you actually gained a few pounds. Or maybe you dropped 10-15 when you gave birth but you can’t figure out why you still look a little pregnant.

You feel tricked. The breastfeeding weight loss mecca you were promised when you were pregnant apparently only applies to Kourtney Kardashian.

If you’re breastfeeding and not losing weight like you’ve been sold, I’m here to explain why.

Before you jump in, please note that I am not a doctor. Do not run out and do everything I say without checking with a doctor first. I’ve just been obsessed with food, nutrition, and fitness for as long as I can remember and have researched the shit out of it.

I struggled with my body changing throughout pregnancy, and everything I'd read online seemed to be anecdotes about women who couldn't seem to lose the pregnancy weight (and for whom breastfeeding did NOT help them “melt off the weight”). I thought I was doomed to struggle.

But that's not been my experience. Like most things pregnancy, newborn and labor-related, my experience has been much more positive than I was led to believe it would be/should be/to expect.

My weight just before birth was 167 lbs. Higher than I'd ever been and steadily creeping upward.

When I had her, I lost 12 lbs within a week – there was the baby of course, the placenta, and so much water weight.

I ate as much (healthy foods, but calorific nonetheless) as possible to promote lactation – things like avocados, nuts, greek yogurt, veggies, fruit, dried fruit etc in the first 3 weeks, and didn't lose a single pound.

But since I started tracking my calories (I use My Fitness Pal) and paying attention to portions and eating lower calorie snacks when I'm hungry (which is all. the. time) like veggies, fruit, popcorn etc, I've lost another 12 lbs in the past 4 weeks super easily.

When my baby was 7 weeks old, I was 143.9 and losing on average around 1.9 lbs/week.

Not exactly “melting off” like Hollywood would have you believe, but not so bad.

3 Reasons Your Not Losing Weight Breastfeeding

I'm not saying it will be the same for everyone, but the reason breastfeeding doesn't work for a lot of people for weight loss is threefold:

Overeating (Yes, Really)

Breastfeeding and healing postpartum makes you ravenous, so you eat more.

But rather than having to cut up veggies etc, it's convenient to grab a handful of nuts or oreos (yum).

WHen people are having a hard time losing weight, there’s almost always only one reason behind it, which is overeating.

Yes, there are metabolic disorders and issues like thyroid dysfunction. I’m not talking about that. Most people don’t suffer with those, and if you do, you should be working with your doctor to find out what you can do to feel better, not reading online articles.

Most weight loss, until you get into peak performance, is down to two things:

  • Calories in
  • Calories out

Yes, there’s a raging debate over whether a calorie is a calorie is a calorie, and the science says not all calories are built the same.

This isn’t a weight loss blog, so I’ll direct you to read more here if you’re interested. For your purposes, you need to know three things:

  1. Calories do matter,  and if you want to lose weight you have to eat at a caloric deficit
  2. You have (almost) complete control over the rate at which you lose weight and hormones don’t play as much of a role as you’ve been led to believe, at least until you get back to pre-pregnancy weight
  3. If you want to get super serious, follow a very low carbohydrate, high fat, adequate protein diet like the ketogenic diet or Atkins.

During pregnancy and postpartum, we’re sold a bill of goods about eating a ton, otherwise you’ll “lose your milk supply”, which is both wrong and silly. I’ll explain why in a moment.

Not Tracking Your Food Intake

Most people assume “healthy” foods are low calorie and that these foods won’t make you gain weight.

Healthy does not = low calorie. Look, almonds are considered “healthy”, right?

But a ¼ cup of almonds, which is roughly a handful, has about 162 calories. Most people don’t eat just a quarter cup, and the average recommended caloric intake is around 2000 per day for women (although, I will say that’s probably extremely high unless you’re either very tall or extremely active).

To lose about a pound a week, relying just on the calories in vs. calories out logic, you need to eat at a deficit of about 500 calories per day. That puts you at 1500 calories for the day — again, if you’re very tall and very active.


I am 5’3, weigh around 120 pounds, and am fairly active. I can maintain my weight if I don’t work out at about 1530 calories per day (per my dexa scan).

If I want to lose a pound per week, I can eat around 1000 calories a day, or work out and burn 300 calories/day to boost that to 1300.

Use this online calculator to crunch some numbers on your own caloric intake.

To give you an example of what 1300 calories looks like, here’s my food diary for December 3:

weight loss breastfeeding food

I follow a ketogenic diet so my chicken noodle bowl had no noodles, but it did have extra veggies and extra chicken, so it would have ended up around the same amount of calories.

That is essentially:

  • Intermittent fasting until 12pm (meaning no food — this isn’t exact since I did have some cashew milk in my coffee and some exogenous ketones)
  • A smoothie for lunch
  • An energy bar for a snack
  • A noodle bowl for dinner
  • One small piece of dark chocolate for dessert

That may seem like a decent amount of food, but that means no glass of wine with dinner, no oreo here or a handful of almonds there, no bites of whatever my spouse is eating. Those calories add up dramatically quickly.

Overestimating How Many Calories Breastfeeding Burns

You’ve probably heard a million times that breastfeeding burns 500 calories a day.

Nope. It's about 20 calories per ounce of breastmilk.

Your brand new, five-week old baby isn't eating 500 calories worth of breastmilk per day.

Those claims that it burns “300-500 calories/day!” are estimating for women who produce a lot of milk and who have exclusively breastfed babies on the older side of the spectrum (think like 5 months old but not eating solids, and are extremely hungry little babies).

Just like you “can't outrun a bad diet”, you can't out-breastfeed a bad diet, either.

I exclusively pumped for my daughter for the first few months, so I knew exactly how much she was eating. And at 4 months old she was eating about 20 oz per day, which means about 400 calories.

There’s surprisingly little science on breastfeeding and how the production of breastmilk happens in the body, but there’s also some scientists that theorize that far, far fewer calories are burned during breastfeeding – they’re merely transferred.

Ultimately, I'm not saying that you should want to lose weight, or that you need to, or that your experience will or should be exactly the same as mine.

But I do think that seeing some positive experiences would have helped me when I was pregnant and desperate to feel beautiful again.

If you’re eating at a deficit (and I mean truly eating at a deficit and tracking your calories, are aware of your BMR and TDEE etc, and not lying to yourself) you will lose the baby weight while you’re breastfeeding.

So How Does Breastfeeding and Weight Loss Work?

Your body literally melts your fat to create breastmilk.

But before you get super excited about this, here are a few things to keep in mind:

  1. If we’re looking at the formula as in “calories in/calories out”, it melts your fat and uses it for breastmilk only if you aren’t consuming enough calories for your body to make the milk directly out of those incoming calories.
  2. If you’re not consuming enough calories for your body to make milk, your body will use it’s fat stores (you know, the ones your body built while you were pregnant) to provide milk to your baby.
  3. Breastmilk is incredibly nutrient-rich. But nutrients aren’t just magically made in your body for your baby’s food – the breastmilk steals those nutrients from your body’s nutrient stores. So if you’re not eating enough, say, calcium, your baby will literally siphon it out of your bones like the little parasites they are.
    1. a ) Side note: that’s why you’re always hungry when you’re breastfeeding. At least at first. Your body is using your nutrients and calories.
  4. Those “quick” one-handed snacks all the reddit moms claim you need while you’re breastfeeding like oreos or granola bars (because apparently carrot sticks aren’t a one-handed snack or something) start adding up with the quickness.

But I Thought Breastfeeding Burns 500 Calories/Day?

Breastfeeding does burn calories.

But it doesn’t unilaterally burn 500 calories/day. The amount of calories breastfeeding burns depends on a few factors:

  1. How hard your body has to work to make the breast milk
  2. How much breast milk your baby is consuming.

The problem here is that unless you exclusively pump, you’ll have no idea how much your baby is consuming each day.

The average is about 700ml of 23 oz for an exclusively breastfed baby – meaning no solids. Note I didn’t say newborn. Newborns eat a lot less. So you might burn that many calories every day for a month or two as your baby gets older, but certainly not from the day your kid is born.

But What About My Milk Supply?


Your milk supply isn’t just going to plummet if you don’t eat at a massive excess. In fact, it’s not going to plummet if you eat at a deficit, either.

There will be a few people uncomfortable with this truth using the lame excuse of “it’s all individual”, but that’s not true. No individual defies science.

Remember how I told you that your breast milk is made from either:

  1. The calories you’re consuming or
  2. The fat stores your body has?

Guess what this means? Unless you have literally nary a pound of fat on your body (in which case why in the world are you reading this article?), your breast milk supply will not be affected. Promise.

One thing that is individual is extenuating factors. For example, if you start eating at a deficit of 350 calories/day and your milk supply drops drastically, you’ll probably blame it on the “diet” you’re on (confirmation bias is a bitch).

But you didn’t even take into account factors like nursing less, your baby’s feeding schedule, how often you’re pumping, and the calorie deficits effective lack of energy to get up in the middle of the night to pump or feed.

What Does Impact My Milk Supply?

What little research has been done on breastmilk and breastfeeding suggests that most “galactagogues” — herbs like Blessed Thistle and foods like oatmeal that are supposed to jog your milk supply — do very little.

The things that do impact your milk supply are:

  1. Demand
  2. Extreme circumstances.

Breastmilk production is an economic event. It’s supply and demand. Baby demands more milk, milk supply increases (not immediately).

That’s it unless you are under extreme emotional or physical stress (food security, extreme poverty, domestic violence, to name a few), or nutritional deficiency to a malnourishment degree.

Neither of these events is something that most readers are struggling with. If you are experiencing extreme circumstances, please stop reading this article about losing weight and seek help.

You’re most likely not losing weight breastfeeding because you’re either overeating, not tracking your food intake, or overestimating how many calories breastfeeding burns. Maybe all three.

That’s good news because it means that it’s fixable.

Start tracking what you put in your mouth. Use an app like Myfitnesspal. Adjust your calorie estimations and eat at a deficit, and you should see the scale moving again.

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