Why are some breastfed babies fatter than others

Why are some breastfed babies fatter than others

We may earn commission from links featured in this post. Read more.

Every mother at one point or another has been told that breast is best and that there is nothing better you can do for a baby than to breastfeed them. So why aren’t all breastfed babies chiseled and look like mini greek gods? Why do formula fed babies slimmer? Why do some of them look fat even though they’re on this super healthy diet?

Well, this article delves into this issue to offer some insight into the world of breastfed baby weight gain and how every single one of their boob experiences can be different.

Baby weight can be misleading

A baby who may appear to be overweight or ‘fatter’ may not be at all. Appearances can be deceiving and it’s difficult to guess what they’re weight is by looking at them and it certainly may not impact health. This can lead to mother wondering if other babies are suffering with obesity or their own baby is underweight.

When mothers get a visit from the health visitor or go and see a doctor they will inevitably weigh the baby and put their weight on the chart, they will then tell you what percentile they are on a scale of 1 to 100. 1 is they are are among the lightest and a 100 means they are on the heavier range. This data can be used in many ways but in general it says if they’re losing, gaining or maintaining weight over time and where there is an associated concerns.

A healthy feeding baby can have rolls and it doesn’t necessarily mean anything, but it is still an interesting question as to why some breastfed babies can be fatter than others.

Can breastfeeding make a baby fat?

Breastmilk is arguably the most nutritionally dense food known to man, breastmilk is almost so pure that there is very little waste involved and why breastfeed baby poo is significantly less smelly than a formula fed baby.

Breastmilk is simply incredible and is literally made to feed your baby, a mother’s milk is so magical that studies have shown that breastmilk can be as unique as a fingerprint which is tailored specifically for YOUR baby. This is the first hint to why one breastfed baby can be larger than another.

That being said, a breastfed baby can still appear to have chubby cheeks, rolls of skin and a portly look on them. Why is that?

It is completely normal for breastfeed babies to have different weights on them, especially in the first 3 months where they feed more than usual and are not mobile yet. But, how they are fed can make a difference:

Exclusively breastfed – The baby only gets their milk directly from the breast only. This means that the milk constantly adapts and changes its composition on a regular basis.

A baby who is breastfed in this way is very unlikely to be ‘overweight’ in an unhealthy way. They are in total control of the flow of milk and when to start and stop. They are also getting plenty of leptin which is a hormone that regulates food intake and energy metabolism. This means that it sends signals to be brain when they are hungry and full.

Because of leptin and all the other nutrients an exclusively breastfed baby is eating, even if a baby appears fatter they will not be in a way which is a risk.

If there are two babies who are exclusively breastfed and one is fatter than the other this is most likely down to birth weight and genetics (40% of an adult’s weight can be inherited) which will balance itself out after 9-12 months if nothing else changes.

Breastmilk has been shown to significantly reduce the risk of childhood obesity and later in life and this is one of the reasons.

Exclusively breastfed and expressed – A mix between being fed through the breast directly and offered expressed milk via a bottle.

This is the same answer as above. Your baby will get getting plenty of nutrition and leptin. However, they can possibly overfeed with the bottle as they can no longer control the flow of the milk as easily.

However, what they do overfeed on is still extremely nutritious and unlikely to make a baby obese even if they look it in the first year. Growth will be constant and depends on many factors but generally the baby fat is mostly gone by 9-12 month old.

Exclusively expressed breastmilk fed – The baby gets breastmilk but it is only fed via bottle after hand expressing or pump. The baby never makes contact with the breast directly. This leads to the milk not adapting as often as the baby’s hormones doesn’t interact with the mother via the nipple.

Secondly, as the milk comes through a bottle there is the possibility of overfeeding from time to time, even more so if the parents want the infant to finish their bottle. However, this is rare as the parents have an infinite supply of it and there is no cost so the incentive to avoid wastage isn’t that strong.

Breast and formula fed – This is when the mother mixes breast milk feeds with formula feeds on other occasions. The baby may get the breastmilk via the breast or the bottle via a bottle maker. Children who are combination fed can be a complex case if there’s suggestion of rapid weight gain. On one hand, the breastmilk is light on calories, low on fat and on the other hand formula feeding involves fatty cow’s milk and no leptin.

The formula feeds can lead to overfeeding and the lack of leptin can leave the hungrier than usual, often mothers who combination feed may be tempted with hungry baby milk which can affect baby’s growth negatively from the extra calories and over-full tummies.

A baby can gain weight fast with formula milk due to parents insisting they finish a bottle based on the instructions by the manufacturers, like a set meal. This changes who decides when a baby is fed – with formula it tends to be the parent who decides this whereas with the breast it is the baby via leptin who decides this.

Ironically exclusive breastfeeding is more likely to create chunky babies than formula fed babies in the first 6 months, but after that and when babies get mobile it changes.

However, even with combination feeding, the reason why a breastfed baby can seem fatter than others is most likely because of birth weight and genetics.

Breastfed and weaning – A baby who is being breastfed and weaned can of course become overweight if what they are weaned on is unhealthy, full of sugar and high on calories. Babies should be weaned by eating healthy foods such as fruits and vegetables wherever possible (a baby blender can be useful) for the length of the process or risk going towards obesity. A breastfed baby who appears fatter than others could be weaned on the wrong stuff.

When could a breastfed baby be fatter than usual?

As we’ve covered already, formula fed babies and exclusive breastfeeding babies can look chunky and that the majority of the time it means nothing at all. However, if you’ve seen a breastfeeding baby who really does appear fatter than usual then here’s some possible reasons outside of genetics and birth weight:

Oversupply – Some women can experience oversupply or as it’s better know as hyper lactation or hyper galactica – this is when they feel engorged and with sore nipples often which can lead to some children to have longer feeds than usual as the breast never feels empty to them. This is a rare occurrence associated with these two conditions.

Mothers who feel they are constantly engorged should speak with a lactation consultant to assess the latch and of course the baby’s weight.

Tandem feeding – Tandem feeding is when a mum feeds two children or more at the same time. This can be a tricky time for the baby as often the let down can be quicker as it has adapted to the feeding style of the current feeder. The milk produced by the mother is suited for BOTH children which means it can be a little more calorie dense and fatty when compared to the milk which would have been made only for the baby.

Secondly, the let down can be a little bit quick for the baby to cope with in the early days which can lead to being overwhelmed with milk, at times.

Underlying health issue – Cushing syndrome, growth hormone deficiency, hypothyroidism, insulinoma, leptin resistance and Prade-Willi syndrome are extremely rare conditions causing even breastfed babies to be fatter than usual.