The Myth That Breastfeeding Helps You Lose Weight
One of the most common things new mothers hear after birth is:
"Don't worry. Breastfeeding will help you lose the baby weight."
Sometimes that's true.
Sometimes it isn't.
And for many women, believing this myth creates unnecessary guilt when their body does exactly what it is designed to do.
Somewhere along the way, "breastfeeding burns calories" became "breastfeeding will help you lose the baby weight." Those are not the same statement.
One is physiology.
The other is a cultural expectation we've placed on mothers.
This Is One of Those Things We've Learned More About
For many years, women were told that breastfeeding was nature's weight-loss plan. It became common advice passed from one generation to the next:
"Don't worry. Breastfeeding will help the weight come off."
Like many areas of women's health, our understanding has evolved.
Earlier beliefs were based on the observation that producing milk requires energy. We now know that while lactation does increase energy expenditure, it doesn't automatically lead to weight loss. The postpartum body is influenced by a complex interplay of hormones, metabolism, sleep, stress, nutrition, healing, genetics, and the demands of caring for a newborn.
In other words, the science is more nuanced than we once believed.
This is a familiar story in women's health. For decades, pregnancy, birth, postpartum recovery, menopause, and female physiology received far less research attention than many other areas of medicine. As more high-quality research has emerged, we've gained a much deeper understanding of how the female body adapts during these seasons of life.¹
Today, the evidence tells us that breastfeeding is an incredible way to nourish a baby—but it should not be viewed as a predictable or guaranteed method of losing weight.²⁻⁴
Your Body Has One Job Right Now: Keep You Alive and Feed Your Baby
From a biological perspective, producing breast milk is incredibly demanding.
Your body uses energy every single day to make milk. Most breastfeeding mothers require approximately 450–500 additional calories per day to support milk production, although individual needs vary depending on milk supply, body composition, and whether breastfeeding is exclusive.²
Many people stop there and assume:
Burning more calories = losing weight.
But the human body is much smarter than a simple calorie calculator.
Your Body Doesn't Know You're Trying to Lose Weight
Your body doesn't know you have jeans you're hoping to fit back into.
It doesn't know what social media says about "bouncing back."
What it does know is this:
A tiny human depends on you for food.
Your brain and hormones respond accordingly.
Many breastfeeding mothers notice they are:
Hungrier than they've ever been.
Thirstier than usual.
More tired.
Craving quick sources of energy.
Those aren't failures of willpower.
They're normal physiological signals designed to protect milk production. Increased appetite during lactation is one of the body's ways of helping meet the substantial energy demands of feeding a growing baby.³
Some Women Lose Weight.
Some Women Hold On To It.
Both are normal.
Research has consistently found that breastfeeding affects postpartum weight differently for different women. Some mothers gradually lose weight while breastfeeding. Others lose very little, and some retain more weight until after weaning. Multiple systematic reviews have concluded that breastfeeding alone is not a reliable predictor of postpartum weight loss.⁴⁻⁵
So why would the body hold onto extra weight?
One of the leading evolutionary hypotheses is that maternal fat stores serve as an energy reserve during lactation.
For most of human history, food wasn't always plentiful. Pregnancy and breastfeeding often occurred during seasons of scarcity, drought, migration, illness, or famine. A mother who carried a reserve of body fat had a greater chance of continuing to produce milk, even when food became temporarily limited. In that environment, retaining some extra body fat could improve the likelihood that an infant continued to receive nourishment during times of uncertainty.
From a biological perspective, those extra fat stores weren't a mistake.
They were part of a sophisticated survival strategy.
Your body doesn't know you have a refrigerator full of food.
It doesn't know you can stop at the grocery store on your way home.
Your physiology was shaped over thousands of generations when those things weren't guaranteed.
During lactation, your body is constantly balancing its own needs with the demands of feeding your baby. One way it may do that is by preserving energy reserves. This is thought to be influenced by hormones, metabolism, genetics, nutrition, and the overall demands placed on the postpartum body.
That doesn't mean every breastfeeding mother will retain weight. Many women naturally lose weight while nursing. But for those who don't, it may simply reflect a healthy biological adaptation rather than a failure of diet, exercise, or willpower.
Instead of asking,
"Why won't my body let go of this weight?"
a more compassionate question might be,
"What is my body trying to protect?"
Often, the answer is:
The ability to nourish your baby.
That's not a flaw.
It's biology.
Hormones Change Everything
After birth, estrogen and progesterone fall dramatically.
At the same time, prolactin—the hormone responsible for milk production—rises.
These hormonal shifts influence much more than milk supply.
They affect:
Appetite
Metabolism
Sleep
Mood
Energy levels
Fluid balance
Body composition
Researchers now understand that postpartum weight change reflects a complex interaction between hormones, metabolism, sleep, nutrition, stress, physical recovery, and breastfeeding itself. There is no one-size-fits-all postpartum experience.⁵
Add in interrupted sleep, healing tissues, caring for a newborn, and the emotional adjustment of becoming a mother, and it's easy to see why postpartum weight isn't simply about calories.
Why This Myth Can Be Harmful
At first glance, telling a new mother that breastfeeding helps with weight loss may seem encouraging.
But when her body doesn't respond that way, the message can quietly become:
"Why isn't it working for me?"
Many women begin to wonder if they're eating too much, exercising too little, or somehow doing something wrong.
In reality, their body may be doing exactly what it was designed to do.
The postpartum body is not failing because it holds onto weight.
It is adapting.
It is healing.
It is protecting milk production while recovering from pregnancy and birth.
When we shift the conversation from weight loss to whole-body recovery, we give mothers permission to appreciate what their bodies are accomplishing instead of criticizing what they look like.
Weight Is Only One Measure of Health
Many mothers become discouraged because the scale isn't changing.
Meanwhile, their body is doing remarkable things.
It is:
Healing after pregnancy and birth.
Producing complete nutrition for another human.
Regulating hormones.
Restoring connective tissues.
Recovering the pelvic floor and abdominal wall.
Adapting to entirely new movement patterns as they lift, carry, feed, soothe, and care for their baby.
Those changes matter far more than a number on the scale.
This Is Why I Don't Teach "Bounce Back"
In my classes, we don't chase weight loss.
We rebuild function.
We restore breathing.
We reconnect the core and pelvic floor.
We improve posture, movement, strength, balance, and confidence.
Healing isn't measured by how quickly your body becomes smaller.
It's measured by how well your body functions.
Ironically, when women stop fighting their bodies and begin supporting them, they often feel stronger, move better, and become more confident regardless of what the scale says.
Healing first.
Function first.
Everything else follows.
Whether you are six weeks postpartum, six months postpartum, or six years postpartum, your body deserves care that supports how it functions—not pressure to look a certain way.
The goal was never to "get your body back."
Perhaps the goal is to move forward with a body that has done something extraordinary.
Pregnancy, birth, and breastfeeding change us. Some of those changes are temporary. Some are long-lasting. All of them deserve to be met with curiosity instead of criticism.
I don't believe in bouncing back.
I believe in moving forward—with a stronger foundation, a healthier relationship with your body, and an appreciation for everything it has carried you through.
A Gentle Reminder
If your body isn't losing weight while breastfeeding, it doesn't mean you're doing anything wrong.
It may simply mean your body is prioritizing the very thing it was designed to do: nourish your baby.
One day, breastfeeding will end.
Hormones will shift again.
Sleep will improve.
Your body will continue changing.
There is no deadline for postpartum recovery.
There is no prize for getting there first.
Your body deserves patience, nourishment, and care through every season of motherhood.
Continue Learning
If you enjoyed this article, you might also like:
Return to Exercise After Birth: Why Slower Is Often Stronger
High-Intensity Workouts, Cortisol, and the Postpartum Body
Postpartum Recovery Isn't About Bouncing Back
Core and Pelvic Floor Recovery: Why Function Comes Before Fitness
If you're local to Boulder County, I'd love to welcome you to one of my Yoga with Baby classes or a private postpartum recovery session. Together we'll focus on rebuilding the foundation your body needs—not just for today, but for the years of motherhood ahead.
References
National Institutes of Health, Office of Research on Women's Health. History of Women's Health Research. https://orwh.od.nih.gov/
American College of Obstetricians and Gynecologists. Breastfeeding Your Baby. https://www.acog.org/womens-health/faqs/breastfeeding-your-baby
Centers for Disease Control and Prevention. Maternal Diet and Breastfeeding. https://www.cdc.gov/breastfeeding-special-circumstances/hcp/diet-micronutrients/maternal-diet.html
Neville CE, McKinley MC, Holmes VA, et al. The relationship between breastfeeding and postpartum weight change: A systematic review and critical evaluation. International Journal of Obesity. 2014.
Tian C, Hu C, He X, et al. Breast-feeding and postpartum weight retention: A systematic review and meta-analysis. Frontiers in Nutrition. 2023.
This article is for educational purposes only and is not medical advice. Always consult your healthcare provider regarding questions about breastfeeding, nutrition, postpartum recovery, or your individual health. If you found this article helpful, you're welcome to share it. If you're sharing it with clients or students, please credit Anne Catherine Yoga. In the spirit of yoga, we practice both ahimsa (non-harming) and asteya (giving proper attribution to the work of others).
