Bottle-feeding and weight gain in infancy: Does it matter what’s in the bottle?

This baby looks delicious (http://nomnommonster.com)

Fearless Husband and I have embarked on a 2-week “cleanse”, meaning we are only eating whole, organic, mostly raw foods. Meaning mommy is without her little helpers, Sugar and Caffeine. Meaning mommy is ornery.

Thus, I hope you’ll pardon the snarkiness which I’m sure will creep in to the following post. I’ve been trying to hold back lately, in the spirit of creating a kinder, gentler, more “professional” FFF, but the lack of food is bringing me back to my obnoxious roots. And it certainly doesn’t help that the study I’m about to dissect is about weight gain in babies (chubby, delicious babies… not that I’d ever eat a baby or anything, being vegetarian and, you know, not a cannibal. Unless the baby was dunked in chocolate… or rolled up in a nice fluffy tortilla….oh my god, I need sugar….) which is one of my biggest pet peeves.

I stumbled upon the study in question via this article, Bottle Feeding Linked to Rapid Weight Gain in Infants, Possible Obesity Risk. Great title, right? The article is correspondingly anxiety-provoking:

In a surprise twist to the “breast is best” debate, bottle feeding, and not just formula feeding, increases the risk of rapid weight gain in infants, leading to an increased risk of obesity later in life, says a recent study published in the Archives of Pediatrics & Adolescent Medicine...The results of the study indicate that breastfeeding, and not just breast milk, is best for babies. Infants who were exclusively formula fed by bottle gained only between 71 and 89 grams more per month than infants who were exclusively fed human milk by bottle. Furthermore, weight gain was negatively associated with the proportion of breast milk feedings but positively associated with proportion of bottle feedings among the infants who received mostly human milk…. In other words, bottle feeding, and not just formula feeding, puts children at an increased risk for rapid weight gain during infancy and for obesity later in life. Breastfeeding, and not just breast milk, is best in terms of maintaining a healthy weight.

Okay, so reading this, I felt conflicted: on the one hand, I am pleased as punch that researchers are looking at differences in the types of milk fed by bottle, and comparing human milk fed by breast to human milk fed by bottle – these are the types of studies that can potentially help us figure out if it something in breastmilk (which could then possibly be recreated to make a better formula) conferring certain benefits, or if it is the act of breastfeeding itself. If it is the latter, then this has obvious implications for working women, and exclusive pumpers, many of whom go to extreme lengths to provide the health-enhancing benefits of breastmilk for their babies. But on the other hand… if this was yet another study linking bottle-feeding to obesity, it wouldn’t really be doing much more than creating more stress and pressure on mothers who were unable to exclusively breastfeed – especially if those who were combo-fed fell prey to the same dreaded weight gain as formula-fed babies.
A quick jump over to the actual study (which is available to the public, free of charge, so I highly recommend taking a gander. It’s always better to go directly to the source. Kind of like my current diet…did I mention I was hungry?) quickly put both my excitement and my fears to rest. And here is why:
1) The study was based on phone surveys done with mothers, who reported both the mode of feeding and infant weight gain. Self-reported information is pretty much the bottom of the barrel when it comes to solid scientific data. It’s notoriously shaky as evidence goes, and especially with something like infant feeding where there is a strong, socially-induced morality/pride factor (especially considering the majority of the women involved were white, middle class, and college educated –  the group mostly likely to initiate breastfeeding and be well versed in the benefits), what someone tells you and what they actually do might be two entirely different things. Point being, this isn’t exactly hard data. Even the weights may have been misreported. The researchers could have asked for physician records to back up their results, but they didn’t.
2) More importantly – the study had fudge-all to do with childhood obesity. All it looked at was the rate of weight gain in the first year. Now, one could take these results and merge them with other studies which associated faster weight gain in infancy to later obesity, but then you’re just taking two observational, intricately confounded studies and throwing them together like a Glee mashup: same old songs, dressed up in a fancy arrangement. This study did not discuss whether the babies were gaining appropriate amounts of weight; we don’t know if the exclusively breastfed babies on the lower end of the curve were underweight or normal, or if the exclusively formula-fed or mixed-fed babies (on the other end) were overweight. All of these babies could have been within normal limits – we’re talking grams here. 

I think it’s a rather daring leap to take self-reported data that shows differences in the rate of weight gain in the first year of a child’s life, and use it to justify the message that “Feeding at the breast needs to be the first feeding choice for babies. When feeding at the breast is not always feasible, supplementing breastfeeding with expressed breastmilk is a good alternative, but special attention is needed for infants’ internal feeding cues while bottle-feeding,” which is exactly how the study authors capped off their conclusion. Where is the discussion of why weight gain in the first year is bad?

Interestingly, the researchers also found that “Infants categorized as consuming ‘human milk by bottle only’ and ‘nonhuman milk by bottle only’ gained more weight than infants fed at the breast only, but there was no such bottle effect observed among infants categorized as consuming ‘human and nonhuman milk by bottle.’” They hypothesize that:


“…(t)his might be owing to the fact that infants in this mixed feeding category were more likely fed at the breast previously than the other 2 groups (data not shown). Our previous study suggests that infants fed at the breast develop a better self-regulation of milk intake, which may be carried over even after feeding is transitioned from breast to bottle. Similarly, mothers who previously breastfed might better recognize infants’ cues of hunger and satiety, which may last even after they stop breastfeeding.”

I view this as a prime example of the Achilles heel of infant feeding research. When your internal bias is strongly in favor of one outcome, it’s too easy to extrapolate. First of all, how did they come to the conclusion that the women feeding both breastmilk and formula by bottle breastfed longer than those feeding exclusively breastmilk by bottle? Perhaps this came from additional survey findings, but since we don’t see this data, I’m going on the assumption that this was simply the authors’ hypothesis.  I think it is an equally plausible explanation that women who are feeding both breastmilk and formula by bottle (this is a group with no physical breastfeeding, remember) were exclusive pumpers, just like the other group, who decided to add formula in at some point. As a former exclusive pumper, every drop you pump is worth it’s weight in gold. If anyone’s going to be “encouraging” a baby to finish what’s in his bottle, wouldn’t it stand to reason that it would be the woman who worked her ass off to provide it’s contents? Perhaps the mixed-feeding group didn’t feel as much pressure to make sure that their babies got every last drop, which helped reduce the risk of overfeeding. (PLEASE note that I am in NO WAY insinuating that all exclusively pumping moms overfeed their kids. I don’t think this, at ALL. I am simply providing an alternative hypothesis that I believe is equally plausible to highlight the tunnel vision so prevalent in this area of research.) Alternately, maybe the act of exclusive pumping makes milk less “filling” in some way (the researchers do briefly discuss hindmilk versus foremilk, which can get a bit screwy with pumped milk, especially if you are combining milk from different pumping sessions) and adding a bit of formula helped the mixed-fed babies feel more full. Regardless, my point is that there are other rational (and perhaps more interesting, in terms of future research) explanations than the one provided by this study’s authors.

You’ve all heard my rants on this before, but I am seriously sick of studies that examine weight gain in babies and attempt to use it as fodder for the childhood obesity hysteria. I read another article about a separate study today, which correlated c-sections with later obesity in infants, and felt the same frustration. This article questioned why, as the rates of c-sections have gone up, so have the rates of obesity. I think this is like asking why the rates of autism have gone up along with the rates of breastfeeding. It’s ridiculous. Childhood obesity is high in this country because our kids eat like crap and sit in front of screens all day. It’s hard to change these behaviors, when you’re on a limited budget, living in areas with poor food options, and working all day to keep a roof over your kids’ heads. And being a little heavy isn’t even a bad thing, as long as you are eating healthfully and moving your body – some folks are genetically predisposed to being a little more fluffy. It’s about overall health, not body weight, and much of the conversation around weight gain and body size seem to ignore all of these considerations in favor of overreaching studies that attempt to pin blame on individuals, while refusing to see them as individuals.

And speaking of that, I’m about to shut down my screen, go drink a glass of spinach and kale juice, and dream about eating crap. Crap is delicious. Which is why is is so much fun to blame our propensity towards pudge to the way our mothers birthed and fed us.

About the Author:

Suzanne Barston is a blogger and author of BOTTLED UP. Fearless Formula Feeder is a blog – and community – dedicated to infant feeding choice, and committed to providing non-judgmental support for all new parents. It exists to protect women from misleading or misrepresented “facts”; essentialist ideals about what mothers should think, feel, or do; government and health authorities who form policy statements based on ambivalent research; and the insidious beast known as Internetus Trolliamus, Mommy Blog Varietal.

Suzanne Barston – who has written posts on Fearless Formula Feeder.


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33 thoughts on “Bottle-feeding and weight gain in infancy: Does it matter what’s in the bottle?

  1. So am I reading this correctly that … the researchers did not … look at the rate of HEIGHT growth in infants as well? If you're talking about obesity, height matters just as much as weight. Are the babies gaining more grams also growing more centimeters? Are they staying proportional? Is anyone looking at the weight-for-height graph?

    Weight alone really means nothing. And really, depending on the height data, the fact that breastfed babies are gaining less could be spun in an entirely different direction … since you WANT babies to grow proportionally.

  2. And what about head size?? < ~~asks the mom with a toddler whose head is in the 90th percentile, unlike the rest of her body. :D

  3. So let me get this straight (I was up late with a teething toddler so bear with me). They phoned–phoned–a bunch of women who claimed to be moms (for all we know, they could have been talking to an aunt or nanny or whoever). Let's assume the people they talked to were all the actual moms–this is a group who is typically sleep-deprived and overworked–and got their RECOLLECTIONS of their babies' weight. They didn't get doctor records to back that up. They DIDN'T EVEN ASK if the babies were underweight or had health issues to begin with. They didn't look at anything in the toddler years–where many, many babies, no matter how they're fed, start to lose the infant pudge because they're walking (or tearing around the house screeching about being a racecar, not that I have firsthand experience with this :P ), and have concluded that yep, those awful bottles are just killing us all with obesity.

    What. The. Hell.

  4. Oh yeah, we have the ultimate in discrepancy between weight/height and head. Off the charts in opposite directions at one point. (But it's an actual medical condition there.)

    It just makes me wonder because when a kid isn't getting *enough*, the weight is sacrificed first, and then the height, and THEN the head, so “gains more/less grams” means NOTHING without the other data.

  5. Our pediatrician has been happy with our daughter's growth because for all she is lighter than average and shorter than average, all of these percentiles have been consistent since she was born. Her favorite phrase is “SOMEONE'S gotta be short and skinny.”

    Coming at this from the other direction, if they want to say bottles/formula make kids fat, I shudder to think what they think a child like mine SHOULD weigh.

  6. My FF son is SKINNY. My breastfed one, so far… not so much. We'll see if he thins out as he gets more active. I know this is off topic, but that BF baby also got one hell of a nasty cold the first time he was exposed to one, even though I should have been making antibodies against it since I was sick too. I firmly believe it's exposure, not infant feeding method, that makes a bigger difference just like I believe it's long-term food choices (and genetics!) that are more likely to influence adult weight (or later childhood weight) than the way or type of food fed as an infant.

  7. I “love” how it says bottle fed formula. Is there another way to feed formula. And, these studies just really make those of us who wanted to breastfeed but couldn't feel even worse. Is that their goal? Seems to be most of the time…

  8. I would just like to say that my 100% formula fed (bottle from dad minutes after she was born & mom was out cold!) 6 month old is consistently in the 30th percentile in weight (despite being born in the 95th percentile?) Also, this little one continues to be in the 90th percentile for height so she's one skinny little lady. No matter how much we've worried about her not gaining enough weight and how much we've “forced” her to try and eat, she has quite the internal regulator and refuses to eat when she isn't hungry. Granted one example doesn't necessarily refute an entire study, but my pediatrician constantly tries to stop me from worrying by saying that its purely genetics that determines weight in the early years.

    And FFF – I think crap food is 100% the reason our country is facing obesity. I spend a lot of time overseas for work and it seems that there is just a lot more fresh & not processed food available everywhere but the US. Why the heck aren't their more studies on the impacts of corn syrup or all that other weird stuff in our foods? I feel like biggest focus is on 6 months – a year of feeding… that CANNOT have as much impact as the remaining 60 – 80 years of food choices in our lifetime. (But hey it is pretty fun to blame the moms!)

  9. Yeah, two babies who are the same height and same weight but have significantly different head sizes will have very different proportions because skulls and brains are heavy!

  10. This is so mind boggling. Of my three kids that got exclusive formula my youngest is the biggest. She does not eat any more than I remember my other kids eating yet she is much larger than my other kids were at the same age (thank goodness that I blogged it all or I would never remember). Did the researchers never even hear of genes and think that many large babies might not have that going for them. I also find it irritating that they did not even look into the future to really see if the child was obese later on.

  11. My son is the same way, really skinny despite all he eats and he was formula fed. I try to get him to eat canned coconut milk based pudding, smoothies, cover his spaghetti with olive oil and so on, but he's always skinny. He got sick recently with a bad stomach bug and lost weight which freaked me out because he's already so skinny. But it runs in my husbands family. All tall and lean. I know he's healthy so I'm fine with that, but talk to the new WIC agency we go to since we moved he's really unhealthy because he's “underweight and anemic.” His iron levels have always been in the 10 range no matter what we do. The other WIC agency and pediatrician knew that was his norm and saw steady good progress in growth.

    My daughter though is chunkier than my son despite drinking Nutramigen, my son drank Similac Sensitive. But she's also taller than he was at her age. She is still on the lean side so to speak, but has more fat than my son. It's just the way she fell. She does breastfeed now and again as a bit of a snack, but definitely not full time or even close to half of the time.

  12. Did they bother to consider supplementing at the breast? If so, I wonder what they would say then because if feeding at the breast is so much better than any other form, according to their theory supplementing at the breast must lead to “healthier weight.”

  13. What really gets me is that the people who claim to be so much more informed than we are are going to use totally bogus research like this to back themselves up, and based on the title alone, lots of people will go for it and use it to bash formula-feeding/bottle-feeding parents.

    If militant lactivists spent the time and energy they do bashing bottle-feeding families instead on insisting on research that's better than this, it would be easier for folks like me to believe they were really looking out for moms and babies instead of just pushing their ideology on people because they can.

  14. This actually reminds me. When I lived in Korea there was hardly any breastfeeding going on and I didn't see a lot of obese children. Also, what about the French? Don't most of them not even try to breastfeed from the begining and yet they're apparently famous for being slim.

  15. That's a great point. My sons are tiny–they have been in the 3rd-5th percentile for height/weight since birth. (they are 3.5yr now). That means, though, that they have been growing at a normal, steady rate, wo/major ups and downs. Also, though they are tiny for their AGE, their height/weight ratio is and always has been in the 50th percentile. I take that to mean that their height and weight are proportionate…most kids around 36inches weight about 26lbs, it's just that most kids hit that size earlier than my children did.

    My boys were mainly formula fed, and they did get some breastmilk (pumped) in the beginning, and their rate of growth did not change when they were switched to all formula. Plus, they always stopped eating when they were full—it was common for there to be .5-1oz left in the bottle after a feeding. I realize this is all anecdotal, but I wanted to share anyway.

  16. And another thing…everyone is worried about the rising obesity levels in children, which implies that way fewer American children were obesity in the 40s,50s.60s, 70s, and 80s. The vast majority of women formula fed during those decades because their doctors told them it was healthier. Somehow, 40yrs worth of children who were formula fed were not obese.

    I agree that genetics plays a role. Diet and activity level could also, plausibly play a role, even a very big role. During those decades, kids definitely didn't log as much screen time. I'm sure there are more processed foods readily available, and that kids whose parents work all day, might be likely to snack on junkfood while sitting in front of the tv. If an adult is home, said adult could cook a decent meal and throw the kid out in the backyard.

    This study is just a waste of resources, because, as you all have mentioned, the data collection was very poor, there was no mention of a follow-up on children over time, and their claims about why they think BFed children are slimmer are made up.

    The bit I don't get is the people whose panties are in a knot over the “public health crisis” that is formula feeding. I've asked what they mean by “public health crisis” and they usually talk about the obesity rates in this country. I don't really see how my friend's obesity affects anyone but my friend, you know? And since some of these lactivist types clearly only care about lording it over other women, and they don't actually care about your individual child, why are they crowing about public health crises?

    • 'I've asked what they mean by “public health crisis” and they usually talk about the obesity rates in this country. I don't really see how my friend's obesity affects anyone but my friend, you know?'

      Where I am, with a socialised health system, the taxpayer picks up the tab for treating health problems related to obesity, so it is considered to be in the public's best interests to try to stop an 'obesity epidemic' erupting.

      Maybe bf is part of the big picture to do with healthy weight gain, but not sufficiently so for 'lactivists' to hang their hats on, IMO. There are so many other factors at play too.

  17. True, but I think it would be hard to find enough babies fed formula via something other than a bottle to get a large enough sample size (that the rules of statistics would allow one to draw any conclusions.)

  18. I just got the results of my own Scientific study back. At my exculsively formula fed daughter's 15 month check up, her height and weight were IDENTICAL to that of her exclusively breastfed older sister at her 15 month check up – to the pound and to the inch! I'm curious if the researchers ever do any type of controlled studies – i.e. same parents, same household, different feeding method. Otherwise, most of these reports just seem so useless….

  19. You took the words out of my mouth. I was thinking “what about height?!” from the second paragraph onward.

    Our peanut is 95th percentile weight. She's also 95th percentile height and is off the lines completely for head circ (courtesy of Dad). She's proportioned….enormous but proportioned.

  20. as someone who excessively expressed bm for my son for 2 months due to a tongue tie, it is insulting. all the information out there is about how breast milk is best, and so i half killed myself to express in the middle of the night so he would be getting some breast milk. then i had to make the decision to stop and start formula feeding, due to being exhausted. Now apparently that was not good enough cause it was not directly from my boob.
    obesity is so complex, ranging from genetic, to environmental, diet factors. one of the most important things is being physically active with your kids. not in my opinion, how a loving, caring dedicated mum gives food for the first few months of life.

  21. As someone with a doctorate in nutritional sciences, I find it quite frustrating that the news media often picks up on poorly designed studies that neglect to include height. There are plenty of studies that are better designed that do show a relationship between how infants are fed and later obesity. What is neglected in some of those studies is looking at the eating habits of the parents which may compensate for or exacerbate how infants are fed earlier on. The key is responding to a baby in ways that don’t override their own hunger and satiety cues. So many of us who were of the generations that had to clean our plates and were stuffed before bed so we would sleep longer aren’t as attuned to listening to our own bodies. My generation was overstuffed with the regimented 4 ounces every 4 hours from birth – which meant we had to cope with the belly aches from our overstretched stomachs and our moms had to mop up after our vomitting half of that back up. Then when we learned to gobble down those super sized feeds we were quickly put on the fewest number of feeds possible, well under what is normal. Thankfully the trend of cleaning your plate has been debunked. Hopefully we can continue to trend more towards responding to our infants in ways that help them retain their natural sense of hunger and satiety.

    Unfortunately some of the popular baby books employ crazy lactoengineering schedules of massaging the heck out of one breast and pumping the other in a misguided attempt to increase the fat content of moms milk due to the mostly misguided noticing about foremilk/hindmilk imbalance. While it can ocasionally occur, it is quite rare and too many moms get entirely too stressed out because of fears about not having enough fat in their milk. There are many ways to stress out moms to the point that they feel the need to nudge theirr babies into eating more than is needed

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