December 26, 2023

#15: Milk Supply 101 Part 1 - The Foundations

Breastfeeding is often considered a "natural" part of motherhood, but natural is not the same as "intuitive" and it often leaves new moms confused, frustrated, and anxious. That's why today's episode is the first in my "Milk Supply 101" series; we're learning all about the basics of your milk supply, including what body systems drive your breastmilk production, busted myths about the composition of your breastmilk, and the two most important things you need to do to establish a thriving milk supply.

About this episode

What you'll learn

  • The anatomy of the breast
  • Debunked myths about breast milk capacity and production
  • Which systems in your body influence milk production
  • The difference between colostrum and regular breastmilk
  • The truth about baby's nourishment during the first week of life
  • Where breastmilk is made in the body
  • Which hormones directly affect your milk supply
  • The two most important aspects of establishing your milk supply


Get on the waitlist for my postpartum cookbook HERE

Purchase The Milk Mama Lactation Cookbook HERE

Learn the anatomy of the breast HERE

Learn about the fat in your breastmilk HERE

Read a study about alcohol and breastmilk HERE

Connect with Karrie Locher (RN BSN CLC) HERE

Connect with IBCLC Allegra Gast HERE


I am so excited for today’s episode because it is the first in a new series I’m starting called Milk Supply 101. If I had a dollar for everytime someone asked me a question about boosting their milk supply, I could retire next year. Some days it seems like every woman I talk to is struggling with their milk supply and very rarely do I talk to moms who feel very confident in their breastfeeding journey.

So, this series is going to cover literally everything you need to know about breastfeeding and your milk supply. And just to give you an idea of how much you’re going to learn, I learned so much doing research and fact-checking my knowledge for these episodes. So if I learned a lot, you’re basically getting a certification of some sort haha.

In fact, this episode is really dense, and if you’re not familiar with some basic medical terms and references, it might feel a little overwhelming, so I recommend a) listening to this episode more than once, and b) checking out the shownotes if you want to read the citations or just read the transcript to better understand the information.

Now, because this is an educational podcast about health and medicine, I have to remind you that it is purely that - educational. This episode, this series, and this podcast is not meant to treat or diagnose any symptoms or conditions you’re experiencing and it will not replace the medical advice from your personal healthcare professional. If you hear something in our conversation that inspires you to ask questions about or make changes to your health, please consult with your doctor or a certified practitioner before doing so. I am also not held responsible for any adverse health outcomes that may occur.

That being said, I did tons of research and cited information from the National Library of Medicine, the Cleveland Clinic, John Hopkins Medical School, the Endocrine Society, and even Medline Plus (the brand that supplies a large number of hospital items and medications), so I’m simply sharing well-accredited information that is publicly available and have cited my sources in the shownotes if you want to learn more.

I wanted to give a quick shoutout to Alexis for her review on episode number 7: “I finally got around to listening to a podcast episode even though I’ve been following your page for a long time now. I just absolutely love how real and down to earth you are, it truly feels like having a chat with a trusted friend or older sister, and the tips you gave helped me to simplify my focus for postpartum and the remainder of this pregnancy. Thank you, Brooke, for sharing your time and your wisdom so that so many mamas like me can feel better prepared and supported.”

So, with all that said, let’s dive into the mechanics of breastfeeding and how to support it foundationally.

The anatomy of your milk supply

To truly understand how lactation works, you need to have a general idea of the anatomy of the breasts and how your body works physiologically to induce lactation. When you understand this, you can make changes to your diet, lifestyle, and treatment plan if necessary, to help you succeed in your breastfeeding journey.

And just so we’re clear, breastfeeding includes pumping. You are feeding from your breast, just adding a middle man, that’s all. When I say breastfeeding, I’m talking about anyone who feeds their baby with milk from their own body in whatever way they choose, whether that’s the nipple or the bottle.

Something else to recognize is the more you know, the more empowered you are to take your health and your baby’s health into your own hands and advocate for what you need. You’ll know what questions to ask, what terms to use, and maybe even have some opinions about what you do and don’t want. In general, knowing more just makes your life easier, even if you seek the help of a medical professional at some point.

Speaking from my own experience, most of my postpartum anxiety with my first baby came from a lack of knowledge. I didn’t know what I didn’t know, and I didn’t know a lot to begin with. Whenever my baby cried, got sick, or just had problems in general, I always assumed it was my fault and worried that something was wrong with my milk. I wish I could visit my newly postpartum self and say, “It’s not your fault, mama. It’s not your fault that your baby is struggling and it’s not your fault that you don’t know very much.” 

That’s why I created The Well Nourished Mama. That’s why I do what I do. Because you deserve to be informed and educated about everything you’re asked to experience and make sacrifices for in motherhood. And if the traditional healthcare system isn’t going to do that for you, then I will.


Before we talk about milk, we need to talk about the girls. Your breasts are made up of breast tissue, mammary glands, and milk ducts, along with your nipple and areola on the outside. All of these specific parts play a significant role in lactation.

Now, I have to tell you the funniest thing. When I was doing research about the anatomy and physiology of the breast, I was reading the official article from the National Library of Medicine and it had the most hysterical way of describing boobs throughout a woman’s life.

Listen to this description about the shape of boobs: “The shape of the mammary gland is hemispherical in young adult females but becomes pendulous in the later stage of life.” Can we talk about pendulous?! What a terrifyingly accurate word to describe our boobs post-breastfeeding and menopause.

Ok, back to the science. Here’s a simple breakdown of the different anatomical parts of the breast: “Embedded in the breast's fatty and fibrous tissue are 15 to 20 glands called lobes, each of which has many smaller lobules, or sacs, that produce milk. Lobules are arranged in clusters, like bunches of grapes. Ducts are thin tubes that carry milk [from the lobules] to the nipple” (excerpt from Memorial Sloan Kettering Cancer Center). I want to highlight the analogy of grapes and talk about the concept of max milk capacity.

Contrary to popular belief, big boobs doesn’t mean you’ll make a lot of milk, and small boobs doesn’t mean you’ll make less milk. Your boob size is determined by the total amount of fatty tissue, while your storage capacity is determined by the total amount of glandular tissue, or lobules, which we compared to clusters of grapes. Storage capacity is “the max volume of milk in your breasts at their natural fullest” (Legendary Milk).

Some women have lots of grapes and some women have fewer grapes. If you have more grapes (remember this is our metaphor for glandular tissue), this means you can make more milk in one feeding and you’ll have less feedings overall in a 24 hour period of time. If you have less grapes, you’ll make less milk in one feeding and you’ll need to have more total feedings in a 24 hour period. 

Pumping moms, I want you to rewind and listen to that again. This is CRITICAL for you to understand. One of the most common questions I get is something along the lines of: “Help, I’m only producing 1-2 ounces of milk per feeding and no matter what I do I can’t pump more. What do I do?” Well, if the foundations are in place, you’re nourishing yourself, and you’re managing stress, then you must just have a smaller storage capacity. This doesn’t mean you’re incapable of making lots of milk in a 24 hour period, this just means you need to pump more frequently than someone else who has a larger storage capacity. 

Something else to note is that if you’re exclusively breastfeeding, you won’t know exactly what your total storage capacity is because you’re not measuring it. What you can do is recognize your baby’s normal patterns of feeding outside seasons of cluster feeding and say, “wow, it seems like my baby nurses frequently. This must just mean I have a smaller capacity” and move on. This might also be a reason why you can’t give up night feedings until it’s time to wean because your supply requires you to feed more than you’d prefer. And that’s just how it goes.

For me personally, I think I have an average capacity. With my first baby, I nursed once on each side during each wake window and twice during the night until we stopped breastfeeding. It’s been about the same with my second baby now, and she’s only 6 weeks old. When I pumped for a couple weeks with my first baby, I averaged 3.5-5 ounces per side per session, which is pretty average. 

With all of this about breastmilk capacity, I hope this eases your mind a bit. I had many moms, including women in my family, that frequently made comments like “wow your baby is eating again? Didn’t he just eat?” or “are you sure he’s hungry?” and it made me doubt myself as a mom and what I’d learned about my supply and my baby’s needs. I wish I’d known this back then so I could simply teach them the science and not feel so judged. So hopefully this helps you with whatever end of the storage spectrum you’re on.

Now, if your head is spinning a bit and I’m still not making sense OR you’re a visual person, I found an amazing table created by the company Legendary Milk that shows you “if you make x number of ounces, this is roughly how many times a day you’ll need to feed/pump to maintain your supply.” I’ve linked it in the shownotes as well as the transcript so be sure to check that out!

Moving on, an important concept you need to understand is that the mammary glands are regulated by the endocrine system. If the word “endocrine” rings a bell, it’s probably because you’ve heard the term “endocrine disruptors” circulating social media in the last few years. (Or you took anatomy in college). I also just did an entire episode about endocrine disruptors, episode 13, so if you want to learn more about that, check out that episode!

But, in case you don’t know exactly what “endocrine” is referring to, let’s do a quick refresher. The endocrine system is a messenger system of hormones that control and coordinate your body's metabolism, energy levels, reproduction, growth and development, and response to injury, stress, and mood. The hypothalamus at the base of our brain is the neural control center for the endocrine system, and it communicates to the pituitary gland, thyroid, adrenals, pancreas, ovaries, and mammary glands. This is important because when you understand what controls the mammary gland, you understand how you can influence the mammary gland to impact your milk production.


Ahhhh, let’s learn about actual breast milk. The first “milk” your baby gets is actually the precursor to milk called colostrum. This is often referred to as “liquid gold” and is only produced in small quantities until your milk actually comes in. Your body begins producing colostrum during pregnancy, and if you notice your breasts leaking at any point during pregnancy, you are leaking colostrum. And I’m going to get ahead of you and say right now that there is no need to collect colostrum before birth. Absolutely no need.

Your colostrum is produced in such small quantities for three reasons: 1) your baby was used to constant nourishment in the womb, so to help them transition to intermittent nourishment, colostrum is given in small amounts to help their bodies adapt; 2) baby's stomach is so small when they're born, they can't handle more milk than colostrum; and 3) scientists theorize that colostrum is trophic, which means one of its main purposes is to signal the hormonal shift in lactation that induces your mature milk.

Speaking of mature milk, your true breast milk comes in about 3-5 days after giving birth and is produced in quantities larger than what baby needs. This is because your body wants to make sure there is enough milk to feed baby during their rapid growth of the first month and give your body time to figure out exactly how much baby needs regularly.

Now, of all the things I could teach you about breastmilk, there are two that are absolutely essential for you to know: 1) breastmilk is made from your blood, and 2) because it's made from your blood, you have the ability to change the nutrient composition of your milk!

Now don't freak out and think that there's blood in your breastmilk - there's not! It’s just made from your bloodstream because that’s where all the nutrients are. Remember, when you eat food, it’s metabolized by your digestive system, then sent into your bloodstream to be transported to the various places in your body. This includes the mammary glands and milk ducts, which are responsible for producing milk.

Understanding this concept is so important because it confirms that what you eat DOES matter but it also debunks some common myths about mom’s diet and how it affects baby. For example, moms are routinely told to avoid cruciferous veggies like broccoli, cauliflower, and brussels sprouts because they’ll make baby gassy. However, the thing that makes you gassy is the high fiber content, and that’s not transferred to your bloodstream; it just stays in your digestive system.

Another example is alcohol. For decades we’ve heard “pump and dump,” but this has since been disproven as effective or necessary. Simply put, pumping and dumping will not clear the alcohol out of your system faster because it’s your liver’s job to detox and clear out the alcohol. This means your breastmilk alcohol content is directly correlated to your blood alcohol content, or your BAC. 

I’m going to quote Karrie Locher, a registered nurse and lactation consultant: “Alcohol moves between the bloodstream and milk to stay balanced. It is then broken down and metabolized by the liver until no alcohol remains. When it leaves the bloodstream, it leaves the milk as well.

The highest alcohol levels in milk occur 30 to 60 minutes after an alcoholic beverage. However, the number of drinks you’ve consumed, weight, and food consumption may also be a factor on ‘when’ alcohol clears your milk.

Increasing alcohol levels can decrease oxytocin release, which can delay or inhibit letdowns. One study showed a decrease in milk intake in infants BF immediately after alcohol intake in mother by 20-23%.

Many women choose to follow the ‘2 hour rule’— nursing or pumping milk for their baby (this can also decrease subsequent alcohol in milk), then consuming their beverage(s), then resuming regular nursing/pumping at least 2-3 hours (for the next feeding) later. If intoxicated, it takes longer for alcohol to leave bloodstream, therefore the milk as well. It may be best to set this milk aside for reasons aside from consumption or disperse!

Infant risk center recommends that after moderate drinking, mothers feed their child when they feel ‘neurologically normal.’ So yes, you can enjoy some social drinks! Do what feels best to YOU!”

Now, as for changing the nutritional composition of your breastmilk, this is going to be an entire podcast episode on its own, so stay tuned for that, but for today’s conversation, I’ll just remind you that the quality of food you eat, as well as your overall gut health, directly impact the quality of your breastmilk and your baby’s gut health.

This is exactly why I wrote my newest cookbook “The First 6 Weeks: A Postpartum Recovery Cookbook” because I wanted to set you up for success after birth. These recipes were specifically developed based on nutritional science and how it relates to trauma, your fight or flight response, and overall healing, so you can truly nourish your body back to equilibrium after birth and heal your gut as quickly and thoroughly as possible. Because, as we’ve talked about for the last 15 episodes, a well nourished mama means a healthy, well nourished baby. If you want to get on the waitlist for when my cookbook will be available for preorder, head to the shownotes and sign up with your email!


High levels of estrogen and progesterone keep you pregnant but also prevent you from making milk, so the crash in hormones that we experience after birth is essential for establishing our milk supply.

Then, in order to maintain our milk supply, we rely on two hormones: prolactin and oxytocin. Without these two hormones functioning optimally, you wouldn’t be able to produce milk.

Prolactin is secreted from your pituitary gland, which we talked about earlier, but it is controlled by estrogen and dopamine. Dopamine inhibits the production of prolactin, and prolactin and estrogen have an inverse relationship, which means low estrogen yields high prolactin levels and vice versa. This is why our estrogen plummeting after birth stimulates our milk supply, and why getting your period back postpartum causes your milk supply to drop!

Furthermore, elevated prolactin levels inhibit the production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are two of the hormones that regulate your menstrual cycle. This is why women who exclusively breastfeed might not get their period back until after breastfeeding is over and why the myth that breastfeeding acts as a birth control has been around for so long.

Now, although prolactin is controlled by estrogen and dopamine, there are things you can do (besides breastfeeding of course) to increase your prolactin levels. According to the Cleveland Clinic, eating, exercise, and sex can all raise your prolactin levels. I don’t know about you, but I just found more reasons to do all of those things!

Now, it’s important to understand that prolactin levels aren’t indefinitely elevated just because you’re postpartum and breastfeeding. Simply put, “Prolactin levels will only spike during periods of nipple stimulation through suckling by your baby. As long as your baby maintains suckling, prolactin levels stay elevated. During periods when you’re not breastfeeding, your prolactin levels decrease, and milk production reduces. If a person doesn't breastfeed their baby, prolactin levels fall to non-pregnant levels after one to two weeks” (Cleveland Clinic). This is why supply and demand is crucial for your milk supply, which we will talk about in a little bit.

The other hormone we need for lactation is oxytocin. This is one of your happy hormones made by your hypothalamus in the brain but stored and released by the pituitary gland. While we often recognize oxytocin as a necessary hormone for happiness, its main biological function is twofold: to strengthen contractions during labor and induce lactation. 

That being said, it also has an adverse effect on cortisol production, meaning surges of oxytocin can inhibit cortisol levels in the body. This is GOOD. To support this, a meta analysis in the National Library of Medicine concluded: “stress‐induced responses can be improved by oxytocin [and reduce cortisol secretion], thus representing a potential therapeutic pathway in postpartum pathologies such as depression… [reinforcing] the notion that oxytocin, at the moment of initiating breastfeeding, acts not only on the physiological condition, but also on the psychic condition of the mother” (PMC2972642).

I personally am so grateful that a hormone that is required for lactation can also help us fight postpartum depression. God is good!

Wow, that was a lot and we’re still not done. But! I hope that section helps you better understand the WHY behind your milk supply. When you know the WHY, you can troubleshoot problems and better communicate with your doctor if you need extra help. You are also better equipped to implement the HOW, which we’re talking about next.

The two foundations of milk supply

Okay, now for the HOW of having a good milk supply. Well, at least the foundational aspects, anyway. There are so many things that influence your milk supply, and one of the reasons I started this series is because I want you to learn about as many of them as possible. 

I don’t want you to fall into the trap of “I must have a low milk supply because I eat dairy” or assume it’s any one thing. While it could be one thing, it could also be many things, and I know there’s so many that you probably haven’t thought about or been taught about. In my opinion, it can feel overwhelming if you think there’s only one reason and it can be overwhelming if there’s 20 reasons, so what this series will help you do is learn about all the different factors that influence your milk supply, but also understand the hierarchy of those factors.

So today we’re focusing on the two things that build the foundation for your milk supply: feeding on demand and latch mechanics.

Feeding on demand, or supply and demand, helps increase and sustain prolactin levels throughout your breastfeeding journey. Simply put, the more you feed your baby, the more milk you’ll make. This applies to both exclusive breastfeeding and pumping. If you want to make exactly enough milk for your baby, just feed them when they’re hungry. If you want to increase your supply to build a stash, feed baby when they’re hungry and pump in between feedings. 

Something very important to know is that you have to fully drain the breast every time you feed to help your body know how much milk to make. If baby is only getting 70% of what’s in your breast consistently, your body will think, “baby doesn’t need as much milk as I’m making, so I’m going to make less.” 

Fully draining the breast also impacts the amount of fat baby gets during each feeding. If you want to learn more about this specific principle, I wrote an entire blog post about it and I’ll link it in the shownotes. It’s all about the science behind the fat content of your milk and 23 ways to change the nutritional composition of your milk. 

Now, for the first 4-8 weeks postpartum, your baby probably isn’t going to be super consistent with how much or how frequently they want to eat, so don’t put too much pressure on yourself with how much milk you’re making, especially if you’re pumping. Things will normalize and you and baby will find a rhythm. For this short period of time, just honor baby’s hunger, help baby learn how to latch properly, and nourish your body so you have all the boxes checked for establishing your supply.

Something else you can do during these first few weeks is prioritize skin to skin contact. Try to nurse baby without your shirt on and have them in just their diaper. If you exclusively pump, just schedule time for what my husband calls “nakey cuddles.” This skin to skin contact will boost oxytocin levels in both you and baby, and when you are both relaxed and happy, you will make more milk and baby will latch better. It’ll also just help the two of you bond, which is really important in general.

Now let’s talk about latch mechanics. I will preface this by saying that I’m not a lactation consultant, so I only have surface level knowledge about this and I certainly can’t diagnose anything, but I can explain the science behind a good latch and how it affects your supply.

Basically, if baby has a poor latch, for whatever reason, they won’t effectively remove milk, which will not only affect the amount of milk your body thinks it should be making but the nutritional composition of the milk, too. It can also lead to complications like mastitis or clogged ducts.

A poor latch could be because of a few different reasons: 

  1. Baby doesn’t get their mouth all the way around the breast
  2. Baby has a lip, cheek, or tongue tie
  3. Baby has tension in their jaw or neck

And those are the main ones that I’m aware of. If you suspect baby might have any of those problems, please schedule a visit with a lactation consultant and get an assessment done. I even recommend having a lactation consultant come visit you in the hospital after birth and watch you nurse, even if you’ve had previous children. Every baby is different and even if you know what to do, it will be different with every baby.

I did this with Hannah, my second baby, after she was born and the lactation consultant said she had a very minor lip tie but it wasn’t big enough to require medical intervention. That being said, Hannah has had a harder time nursing, so we’ve had to do some extra work with her and I might be taking her into a chiropractor soon if things don’t improve.

I digress. Let’s quickly talk about latch mechanics if you’re pumping. While baby isn’t latching at the breast, you still have something latching onto you and because the plastic doesn’t move, this can actually make things more difficult. To get a good “latch” with your pump, you need to have the proper flange size. I couldn’t begin to tell you how to do that because I don’t pump, so that’s all I can tell you. 

So instead of guessing, just have a lactation consultant measure you and get you the proper flange size. My friend Allegra is a phenomenal IBCLC and she would love to help you with that, so I’ll link her info in the shownotes if you want to reach out to her for any breastfeeding mechanics questions or concerns.

To summarize, feed your baby when they’re hungry and make sure they’re latching well. If you can get those two things in place, you’re set up to produce milk. As for how nutritionally dense your milk is, how much milk you make, and how depleted you get as the milk source, is a whole other conversation that will be continued in the next episode of the Milk Supply 101 series, so stay tuned for that!

Closing remarks

Wow. I don’t know about you, but my brain is tired from today’s episode. We covered A LOT and this was just the first episode of the milk supply series! I just want you to know that my script for this episode was 9 pages long and it took me almost two weeks to write. I really put a lot of time, research, and thought into what I was going to say and I hope you learned something. If anything, I hope you know I really want you to succeed and I’m doing everything I can to support you in your journey.

If you found today’s episode helpful in any way or you know a mama who needs to hear it, please share this episode! And if you want guidance on how to apply what you’ve learned today, my lactation cookbook is exactly what you need. Inside my cookbook, I get specific about the relationship between nutrition and your milk supply, as well as how to adjust your diet and lifestyle with certain situations like returning to exercise, getting your period back, and you or baby getting sick. I also share over 50 delicious recipes that will support your milk supply with minimal prep time or ingredients. I’ve linked it in the shownotes, so be sure to check it out!

Lastly, if you thought of any questions related to our conversation today, please please please shoot me a DM or email me! In addition to all the informational episodes in this series, I want to do an entire episode of just Q&As and while I do have some questions written down, I need your input too!

As always, thank you for being a part of this community and trusting me to be a part of your village. I hope I can continue to be a source of inspiration, education, and encouragement to you as you embrace motherhood. I’ll see you in the next episode mama.