Can A Breastfed Baby Be Overweight? 9 Facts To Know

Can A Breastfed Baby Be Overweight? 9 Facts To Know

Leading health organisations such as Australia’s National Health and Medical Research Council (NHMRC), the American Academy of Pediatrics and the World Health Organization all recommend exclusive breastfeeding for 6 months (or ‘around’ 6 months).

They also recommend that solids be introduced while breastfeeding continues for at least one year.

Therefore, if you’re exclusively breastfeeding your baby, you’re doing what all the world’s leading health organisations recommend.

But imagine this: you take your baby for her regular visit to the child health nurse. She is measured and weighed and, to your astonishment, you’re told that she’s too fat and you’re feeding her too much!

So you throw your hands up in the air and think to yourself, “But how can that be? I’m exclusively breastfeeding her!”

Can a breastfed baby be overweight?

Here are 9 things you need to know about breastfeeding and weight:

#1: Exclusive Breastfeeding Definition

Firstly, it’s important to define what exclusive breastfeeding means.

Exclusive breastfeeding means that a baby only receives breastmilk. No other liquid or solid food is given, not even water.

A baby who is only fed directly from the breast or fed only breastmilk (from a bottle, breast or a combination of these) is said to be exclusively breastfed.

#2: Bottle Feeding Is Different From Breastfeeding

How a baby feeds from a breast is very different from how she feeds from a bottle.

When a baby sucks at the breast, she is in control of how much she drinks. She can suck in a way in which she swallows (nutritive sucking) or she can suck without swallowing (non-nutritive sucking). She can be at the breast and not suck at all, or she can just detach herself.

Therefore, no matter how many times a baby breastfeeds or for whatever reason, she remains in control of her intake.

On the other hand, when a baby drinks from a bottle (regardless of what is in the bottle) she cannot suck in a non-nutritive way. A firm bottle teat in her mouth provides a strong stimulus for her to suck and when she does, she gets milk whether she needs it or not. The relatively fast and continuous flow of milk from a bottle means she needs to keep sucking — or be flooded with milk.

Unlike feeding at the breast, drinking from a bottle means it’s possible for a baby to drink more than she needs.

#3: How A Baby Is Fed Influences The Risk Of Obesity

A baby can be fed in numerous ways. She might be:

  • Exclusively breastfed directly from the breast
  • Exclusively breastfed directly from the breast and with breastmilk from a bottle
  • Exclusively breastfed with breastmilk from a bottle
  • Mixed fed with formula from a bottle, and breastfed directly from the breast
  • Mixed fed with formula and breastmilk from a bottle
  • Mixed fed with formula and breastmilk from a bottle and breastfed directly from the breast
  • Fed directly from the breast using a breastfeeding supplementer. With this method a baby might receive only breastmilk, or breastmilk and formula
  • Formula fed

Within all of these different feeding methods, there are variables such as:

  • What percentage of the time each method is used, and for how long
  • How the baby is fed (e.g. with a schedule or according to need, paced bottle feeding or not)

These factors can influence health outcomes, including weight gain.

When it comes to research, it’s very difficult to tease out all the different variables.

Nevertheless, what current research tells us is that, on a population level:

  • There is no evidence suggesting exclusive breastfeeding increases the risk of becoming overweight or obese
  • Formula feeding is associated with an increased risk of obesity

#4: How Formula Feeding Can Increase Risk Of Obesity

Formula feeding can increase risk of obesity because formula:

  • Comes with instructions about how much and how often to feed a baby — this might prompt parents to encourage their baby to finish the bottle
  • Does not contain the hormone leptin, which helps regulate food intake. Therefore a formula-fed baby’s self-regulation might be reduced
  • Has a higher protein content than breastmilk, which can contribute to more rapid growth

If you are formula feeding, according to need, choosing a formula with a lower protein content and using a paced bottle feeding method can help reduce the obesity risks associated with formula feeding.

#5: Formula Fed Babies Put On Weight Differently From Breastfed Babies

In the first few months, formula fed babies tend to grow more slowly than breastfed babies. After that, formula fed babies tend to grow more rapidly than breastfed babies.

There are wide variations when it comes to average weekly gains for a breastfed baby. It’s normal for weight gains to vary from week to week.

As a rough guide, the NHMRC recommends the following for weight gain in infancy:

  • Birth – 3 months: 150-200 grams per week
  • 3 – 6 months: 100-150 grams per week
  • 6 – 12 months: 70-90 grams per week

#6: A Mother’s Diet Does Not Influence The Energy Content Of Her Breastmilk

A mother’s diet does not have an impact on the energy content of her breastmilk. This is because the energy content of breastmilk is determined by its concentration of fat, lactose and protein. A mother’s diet does not affect the overall content of these macronutrients in her breastmilk.

#7: Feeding According To Need Is Appropriate

Regardless of how a baby is fed, feeding her according to need is appropriate. This helps to ensure she gets the right amount of milk she needs.

Feeding according to need is also important for a breastfeeding mother; it helps her milk supply continue to match her baby’s needs.

#8: Breastfeeding Is Not Magic

Breastfeeding is not magic. How an individual is fed as a baby is just one of a myriad things that can influence whether the individual becomes overweight or obese. Genetic and lifestyle factors, for example, also play a role.

If an exclusively breastfed baby ends up overweight or obese later in life, it would not be because she was exclusively breastfed.

#9: There Are Factors That Can Cause Rapid Weight Gain In Exclusively Breastfed Babies

There’s no evidence that a baby who gains weight rapidly on breastmilk has an increased risk of being overweight or obese later in life. However, here are some factors that might contribute to rapid weight gain in an exclusively breastfed baby:

  • If your family members grew quickly as babies, it could mean your baby might tend to do the same
  • If you have an oversupply, this can result in more rapid weight gain in your baby. An oversupply is only of concern if it is causing problems for you or your baby
  • A medical condition or medication. On rare occasions, if a baby has a certain health problems (e.g. kidney or hormonal problems) or has to take a certain medication (e.g. corticosteroids) these factors could contribute to more rapid weight gain

So, if you’re exclusively breastfeeding and your baby is on the chubby side — relax! This is just how she is meant to be.

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Renee Kam is a mother of two daughters, an International Board Certified Lactation Consultant (IBCLC), a physiotherapist, author of 'The Newborn Baby Manual' and an Australian Breastfeeding Association Counsellor. In her spare time, Renee enjoys spending time with family and friends, horse riding, running and reading.


  1. I’m so glad to see this article because my baby girl has been told over weight 2 days ago when we brought her to normal checkup. She was born at 3.4kg, now after 5 months plus 3 weeks, she is already 8.7kg, which the doctor said she is a bit overweight. She has been exclusively breastfeeding from breast according to her needs, which means about every 1-2 hours. However, l’m still not sure if this is oversupply or not.

    1. My baby girl is also 5 months and weighs 19 lbs 6 oz. She was born at 38 weeks weighing in ar 7 lbs 2 oz. Her pediatrician says she is overweight which to me makes no sense seeing that she is exclusively breastfed and feeds on demand. The doctor told me to introduce rice cereal to her diet to help with the weight gain. I will most definitely not be doing this. When she is 6 months I will introduce solid foods but definitely not rice cereal at 5 months! My mother who is a nutritionist who trains doctors and nurses told me that many doctors base the weight evaluations using a weight for age curve when they should in fact be using a weight for height curve (I mean it makes sense that a taller/longer baby will likely weigh more than a shorter baby) so plotting your baby’s weight on the weight for age curve will likely show her as being overweight which is not an accurate evaluation. Hope this comment helps other breastfeeding mothers out there with babies who have been classified as overweight.

  2. I really liked this article. Still i find my baby too heavy- 5 mo, 22 pounds and 28inches- he has been exclusively breastfed, he has always been big (macrosomic baby), even on my belly and was born 9,4pounds. My pediatrician recommended giving him water before I fed him… and i have been trying to do that. I am not sure if i should ask for tests but when they did them when he was born, everything looked ok. not sure what to do though.

  3. Doctor said my daughter has breast milk obesity and should STOP breastfeeding her. I was modified. She gave me a paper to take to the lab to find out if way my Daughter is gaining a lot of weight.I haven’t gone it’s weighting on my mind that I may be making a baby weights 15.9 kg.

  4. My 14month old daughter ways 13.5kg, on breast milk and little bit of solids but she prefers more of breast milk than solid food am worried cause she is obese already sum1 help cause am thinking of cutting breast milk completely.born weight 3.9kg

  5. Our pediatrician said my exclusively breastfed son was obese at 4 months and wanted us to start solids early. I thought this was bad advice and changed pediatricians. My son is now 11 and is as thin as a rail.

  6. I would love to know why this article only refers to baby as “She” and I’ve noticed a lot of times that baby’s are referred as only “she” Would be nice if this information didn’t favor girls over boys.
    “Unlike feeding at the breast, drinking from a bottle means it’s possible for a baby to drink more than she needs.”
    “But imagine this: you take your baby for her regular visit to the child health nurse. She is measured and weighed and, to your astonishment, you’re told that she’s too fat and you’re feeding her too much!”
    “How a baby feeds from a breast is very different from how she feeds from a bottle.”
    Just some examples was all “she” and “her” not one “he” or “him”.

    1. I’m a first time mom to a baby girl and as a new mother I read a lot of articles about babies, their development, needs etc.
      if the article answers my questions and gives me the information I need, it doesn’t matter what pronoun was used.
      Try to see the article for what it’s really teaching you about and fluffy extras that don’t influence the information.

  7. My granddaughter is 3 months old and getting breast milk only and she is fat….obese…she fas actual rolls on arms and thighs……do not believe this article.

  8. I feel that when I’m at home baby eats more. When we are spending time with others she is less hungry therefore she loses some fat. She’s never skinny. I feel that it’s better to get out of the house or have people over so she’s less bored, she is even more sleepy and that’s good for me! Today,I decided to stay home and she won’t stop feeding.

  9. My son is 4 months old and weighs 9.0kg ,his height is 61cm and i regret to even start mix feeding ,only gave bottle once or twice a day but stopped because i got so concerned that my baby might be gaining too much yet he doesn’t seem to be getting enough cause I’m always breastfeeding and I’ve lost alot of weight just from that.i’m just concerned of bthe problems he might have later on and he even struggles to sleep i have to be next to him all the time or hold him.he barely sleeps!!!

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