If breastfeeding reduces obesity why did obesity soar as breastfeeding rates rose?


There’s a new paper about breastfeeding and obesity, Infant Feeding and Weight Gain: Separating Breast Milk From Breastfeeding and Formula From Food, being highlighted in the mainstream press. It claims to show that breastfeeding reduces obesity.

Really? Then why did obesity soar as breastfeeding rates rose?

[pullquote align=”right” cite=”” link=”” color=”” class=”” size=””]It’s almost like breastfeeding has no relationship with obesity at all![/pullquote]

Because breastfeeding does not reduce obesity. The claim is a product of the motivated reasoning that characterizes nearly all breastfeeding research.

Let’s take a look at what has been happening with obesity rates in the US:


As this graph from the CDC shows, US adult obesity has risen at an astounding rate. The prevalence of obesity has more than tripled from 10.7% in 1960 to 35.9% in 2010.

What was happening to breastfeeding rates at the same time?


I added the green line for breastfeeding rates. You can see that the rate of breastfeeding rose dramatically during that time. That DOESN’T mean that breastfeeding causes obesity, but it does show that it doesn’t prevent it.

What about childhood obesity? Perhaps there’s a benefit in children that we haven’t seen yet in adults.


Obesity has risen dramatically in every age group from 2 to 19 years even though breastfeeding rates were soaring.

How does childhood obesity vary by race?


That’s curious. Though Hispanics have breastfeeding rates comparable to or higher than white babies in the US, they also have the highest rate of childhood obesity.

It’s almost like breastfeeding has no relationship with obesity at all!

So how can breastfeeding researchers claim with a straight face that breastfeeding reduces obesity?

The authors of the new paper acknowledge that the connection between breastfeeding and obesity is tenuous at best and possibily non-existent:

Breastfeeding has many established benefits for maternal and child health, but its impact on obesity is unclear. In a meta-analysis of 113 studies, it was found that breastfed infants have a 26% reduced risk of obesity later in life; however, considerable heterogeneity was observed, and the association was attenuated among high-quality studies.

No matter. Breastfeeding researchers really, really want to claim that breastfeeding prevents obesity so they’ve undertaken a series of mental gymnastics to reach that conclusion. It involves creating the new diagnosis of infant “obesity” and recalibrating infant growth curves downward. I wrote about those mental gymnastics when critiquing a previous paper published by members of the same group that published this one.

Infant “obesity” was defined as more than 2 standard deviations from the mean of infant weight for length.

The Obesity Medical Association defines obesity as:

a chronic … disease, wherein an increase in body fat promotes adipose tissue dysfunction … resulting in adverse metabolic, biomechanical, and psychosocial health consequences.

As far as I can determine, there’s no evidence that infants whose weight for length is more than 2 standard deviations from the mean are suffering from any adverse metabolic or biomechanical consequences. So infant “obesity” may not be obesity at all.

Furthermore, this “diagnosis” is only made possible by a change in infant growth charts.

Why were infant growth charts changed? Previous standards evaluated growth based predominantly on formula fed infants since most infants were formula fed at the time they were developed. Many breastfed infants were diagnosed as underweight using these charts. Breastfeeding advocates claimed that it was wrong to evaluate breastfed infants using formula fed infants as the standard.

They had a point, but it’s not clear that it was a valid one. It’s based on the assumption that every breastfed infant is fully fed when the reality is that breastfeeding has a significant failure rate and some breastfed babies are actually underfed. Far fewer babies receiving formula are underfed since they can eat until satiety instead of merely until the milk runs out.

The WHO charts purportedly show “how infants and children should grow rather than simply how they do grow.” But they don’t measure how infants “should” grow, they measure how breastfed infants, including underfed infants, grow. It’s a classic example of the naturalistic fallacy: if something is a certain way in nature, that’s how it ought to be. But that’s makes as much sense as constructing a child growth chart including those with rickets to evaluate contemporary children who have easy access to calcium and vitamin D.

The conclusions of the new paper must be considered in light of this information.

The authors report:

Among 2553 mother-infant dyads, 97% initiated breastfeeding, and the median breastfeeding duration was 11.0 months. Most infants (74%) received solids before 6 months. Among “exclusively breastfed” infants, 55% received some expressed breast milk, and 27% briefly received formula in hospital. Compared with exclusive direct breastfeeding at 3 months, all other feeding styles were associated with higher BMIzs: adjusted β: +.12 (95% confidence interval [CI]: .01 to .23) for some expressed milk, +.28 (95% CI: .16 to .39) for partial breastfeeding, and +.45 (95% CI: .30 to .59) for exclusive formula feeding. Brief formula supplementation in hospital did not alter these associations so long as exclusive breastfeeding was established and sustained for at least 3 months. Formula supplementation by 6 months was associated with higher BMIzs (adjusted β: +.25; 95% CI: .13 to .38), whereas supplementation with solid foods was not. Results were similar for weight gain velocity.

CONCLUSIONS: Breastfeeding is inversely associated with weight gain velocity and BMI. These associations are dose dependent, partially diminished when breast milk is fed from a bottle, and substantially weakened by formula supplementation after the neonatal period.

The implication is that babies who receive anything other than breastmilk directly from the breast are “overfed,” because the authors assume that all breastfed babies are fully fed.

But the reality that a substantial proportion of women (up to 15% of first time mothers) will be unable to produce enough breastmilk to fully nourish their babies. Therefore some breastfed babies are almost certainly being underfed. Those babies are more likely to need supplementation and early introduction of solids in order to thrive. In other words, the supplemented babies may be the normal ones, and the breastfed babies may be underweight.

The authors insist:

This study confirms that sustained and exclusive breastfeeding is associated with favorable anthropometric outcomes during infancy…

But that’s not what the study shows at all. It merely shows that sustained and exclusive breastfeeding is associated with LOWER anthropometric outcomes; the authors assume lower is better but it may actually be worse.

The bottom line is that if breastfeeding doesn’t reduce obesity in adulthood and it doesn’t reduce obesity in childhood, there is no practical import to reducing “obesity” in infancy.

Let me amend that: there’s no practical benefits to babies, children and adults, but there is a practical benefit for breastfeeding researchers. By making up “benefits” of breastfeeding, they justify their cult-like belief that breast must be best.

18 Responses to “If breastfeeding reduces obesity why did obesity soar as breastfeeding rates rose?”

  1. rational thinker
    September 27, 2018 at 7:57 am #

    I find it amazing how people just take these types of articles at face value. I personally have a friend that believes all the news articles on facebook are true. Why dont people question things anymore? Its easy to see if something is true or not with some simple research. Is it just they dont want to put in the effort to find out.
    I guess maybe health has become increasingly like religious belief. This article does seem to have been written following belief and not actual science. Breastfeeding has a belief structure to it and its costing the lives of the ones most vulnerable.

    • Cartman36
      September 27, 2018 at 10:30 am #

      I think it is because we went so fast from the only way to get information was through sources like the newspaper and encyclopedias that were thoroughly fact checked to anyone can post anything and people believe it.

    • Cartman36
      September 27, 2018 at 10:30 am #

      I think it is because we went so fast from the only way to get information was through sources like the newspaper and encyclopedias that were thoroughly fact checked to anyone can post anything and people believe it.

  2. Young CC Prof
    September 26, 2018 at 9:29 pm #

    Oh, the unwarranted assumptions..

    What they proved was that, on a population of Canadian women, mostly although not entirely of higher socioeconomic status, exclusively breastfed babies gained weight a bit slower during the first year of life. To get from there to “breastfeeding prevents obesity” we would also need:

    1) That the results generalize, including to populations with different breastfeeding behaviors and populations at high risk of obesity and metabolic diseases.

    2) That there is a relationship between infant weight gain and adult weight and metabolic health, other than possibly at true extremes.

    3) That this relationship is driven by environment factors in infancy such as feeding, rather than size genes.

    4) That the breastfed babies’ growth rate was a sign of optimal nutrition and the formula-fed babies over-nutrition, rather than some of the breastfed babies being underfed. As far as I can tell, the researchers made up the two standard deviations thing.

    Aside from all the other problems with underfeeding, deprivation in early childhood in a food-rich society is a GREAT way to wind up with lifelong weight struggles and early Type 2 diabetes, because your metabolism essentially gets programmed for famine.

    • fiftyfifty1
      September 27, 2018 at 10:10 am #

      “deprivation in early childhood in a food-rich society is a GREAT way to wind up with lifelong weight struggles…[…]… because your metabolism essentially gets programmed for famine.”

      That’s one idea that gets a lot of media attention. But it has minimal evidence, and conflicting evidence is starting to appear. One of my kids is involved in a large study of early nutritional deprivation (adopted babies and toddlers who arrive seriously underweight.) The researchers expected to see this problem, but so far are NOT finding it. They are not finding an increased rate of obesity/overweight at all.

      • BeatriceC
        September 27, 2018 at 10:45 am #

        I’ve been curious about this for a long time now. I have a different theory on why early starvation might cause life time issues. All of the people who I’ve talked to who have had known or suspected early starvation, including myself, all have complicated relationships with food. I think it’s possible that early starvation may contribute to difficulty managing portion sizes, stress eating, and things of that nature. One of the reasons I think along those lines is from working with rescue animals. When an animal experiences food scarcity, they frequently binge eat and get very protective of what food they do have, and frequently maintain these behaviors for years, even after steady food supplies have been established. It’s possible then, that at some very deep seated psychological level, people who were accidentally or intentionally starved as newborns may be at higher risk for psychologically based food and eating issues than somebody who was fully fed. Those issues, in turn, could lead to obesity. I don’t think it’s a sure thing, obviously, but I think it’s worth further studies.

        • seenthelight
          October 2, 2018 at 12:26 am #

          I recommend checking out Dr Ellyn Satter’s work. The library should have it. To me, she seems like the Dr Amy of eating. I’m not kidding you – I was worried when i read it. I thought oh Lord if I eat this way I’m gonna gain twenty pounds – but I was convinced to try it for the kids, so we went for it, and we’ve stayed steady. I haven’t had to buy new (bigger) clothes. And I eat cookies. I feel like Oprah about bread in that commercial.

          I have two kids – one seemed bigger than she should be, while the other seemed smaller. Satter’s writing helped me see that letting them graze, rather than having regular sit-down snacks and meals, was actively encouraging that trend – oops! But it’s okay, because sticking to the process will bring them to their ideal places naturally.

          But yes, newborn deprivation should absolutely be studied. Are these kids losing IQ points? I’m so thankful I found out about all this before my second and supplemented with formula immediately.

      • Young CC Prof
        September 27, 2018 at 12:24 pm #

        Hmm, that’s interesting. (Also good, because both of my kids were born pretty skinny.)

  3. The Bofa on the Sofa
    September 26, 2018 at 5:52 pm #

    Yep. It’s true that the growth curve for breastfed babies lags behind that for formula fed babies. There are at least two explanations:
    1) Formula fed babies are getting too much
    2) Breastfed babies aren’t getting enough
    3) Combination of the two
    4) Other

    Why jump to conclusion 1?

    As has been pointed out, normally, faster growth is consider a sign of better health, not worse.

    And, as a reminder, PROBIT found no indications that formula feeding led to obesity later on, so the question is, what’s the problem?

  4. The Kids Aren't AltRight
    September 26, 2018 at 5:30 pm #

    I have had to supplement my daughter since she wasn’t gaining enough weight or dirtying enough diapers. It is amazing how many people keep advising me to starve her rather than supplement. I would bet that starving breastfed babies are keeping the average bmi down.

  5. Angharad
    September 26, 2018 at 2:33 pm #

    1) The study authors did a great job villainizing feeding babies expressed breastmilk – it’s not enough to pump at work and have someone feed the baby that milk, you really do need to be at home with the baby or you’re jeopardizing their health.
    2) This fear of being fat is ridiculous. In college I maintained a weight at the very bottom of the “healthy” BMI range by eating 1200 calories a day (at 6 feet tall) and running 10 miles a day. I blacked out every time I stood up, my fingers and toes would literally turn blue if I was in an ambient temperature less than 75 degrees, my fingernails broke and split, and I missed my period for six months at a time. Now I’m within 2 pounds of “obese” and I have had literally no observable daily effects from it. And yet, I was complimented by EVERYONE (including medical professionals) for my “healthy” weight then, and have been encouraged by some to try to lose the weight again.

  6. September 26, 2018 at 1:59 pm #

    The only thing I see the preoccupation with childhood weights creating is an unhealthy relationship with food and a lifelong fear of being fat. I’d love to see the chart of kids suffering dysfunctional eating behaviors (anorexia/bullimia/etc.) over the same time period. People come in a variety of shape and sizes, and the assumption that fat is not healthy and thin is healthy harms many. The fact breastfeeding advocates have jumped on this highlights their willingness to capitalize on any social stigma they can. People fear their children won’t be attractive or smart – so what do breastfeeding gestapo do? Claim that if you don’t breast feed your child will be doomed to be less attractive and less smart.

    • Sarah
      September 26, 2018 at 2:20 pm #

      Oh it’s definitely bandwagon jumping.

  7. September 26, 2018 at 1:29 pm #

    In my experience, the fattest babies have been the exclusively breastfed infants whose mothers won’t use pacifers other than their own nipples. The baby is in effect noshing 24/7 and gains weight accordingly.

  8. Cartman36
    September 26, 2018 at 12:38 pm #

    Of all the stupid claims about BF, reducing obesity may be the stupidest.

    One, if you have enough of a commitment to health to breastfeed especially long term, then you probably have a strong commitment to other healthy behaviors. Example, I was at McDonald’s recently and I overheard a mother, when questioned by her child why the child couldn’t have a cheeseburger or nuggets that it was because the filet-o-fish sandwiches they were eating are the “healthy” option and they were no longer eating “unhealthy” stuff. Don’t get me wrong, I love the filet o fish but a fried fish patty covered in cheese and tartar sauce is not “healthy”. My point is, that the mother probably really believes that it is the healthier option because it is fish. I have the education (and my mother is a dietitian) to limit how often we eat fast food regardless of what we order. (***I don’t know this woman and I only overheard this one exchange so my intent is not to criticize or judge her but rather I think its a good antidote to highlight that people can have very inaccurate beliefs about foods***).

    Two, what evolutionary pressure would there have been for BF to reduce obesity since for most of humanity we didn’t live long enough or have access to enough food to be obese???

    • Sarah
      September 26, 2018 at 12:43 pm #

      We appear to have cross posted on the last point…

      Honestly though, there must be humans who only survived periods of scarcity and famine because they managed to scarf down an above average amount of the high calorie stuff when it was available. Not stopping eating when you’re full has probably saved lots of lives.

  9. Sarah
    September 26, 2018 at 12:31 pm #

    Said this before I know, but the attraction to the idea that breastfeeding reduces obesity is mystifying, since the things that make us obese would have been positive traits for most of human history.

    More than a small minority having access to sufficient food, all the time, and being able to choose what we want to eat is a very new thing for our species. Moderation being a good thing is very new. With that in mind, preference for high calorie food whenever we can get it and ability to gain and keep on weight have usually been evolutionary advantages. Still are in a few places. Why on earth would we evolve a feeding method that made us less likely to have these advantageous traits? It’s counter-intuitive.

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