Does Prolonged Bottle Feeding Drive Obesity?

Yesterday, the media were awash with reports on a new study out from Temple University, Phildadephia, regarding the strong association between bottle feeding beyond the age of two and the prevalence of childhood obesity at age 5 1/2.

In this paper, published in the Journal of Pediatrics, Rachel Gooze and colleagues examined data on 6,750 kids born in 2001 from the Early Childhood Longitudinal Study, Birch Cohort.

According to their analysis, about 23 per cent of kids, bottle fed after age two were obese at 5 1/2, compared to only 16 per cent of kids who were off the bottle.

Surprisingly, more than one in five kids over the age of two were still using the bottle as their primary drink container and/or were being put to bed with the bottle.

In an interview with Anne-Marie Tobin from the Canadian Press, I offered the following comments:

“Liquid calories tend not to have the same effect on satiety, or feeling full, as solid calories. In an older infant, it’s usually that the calories in the bottle are on top of what that kid might be eating, because those liquid calories have virtually no effect on satiety or hunger.”

“Thus, as discussed in the study, if a 24-month-old girl of average weight and length who is put to bed with a 250-millilitre (eight-ounce) bottle of whole milk, receives approximately 12 per cent of her daily caloric needs from the bottle, this might be fine if the child is eating 88 per cent less calories in regular meals throughout the day”

“But what happens in reality is the kid will eat 100 per cent of the calories it needs, and then you’re adding another 12 per cent at night because you’re giving her the bottle to put her to sleep.”

I also noted that:

“When kids are at this crucial stage of development, issues of satiety, appetite, hunger and a reward system are being hard-wired into a child’s brain, and they’re very hard to undo.”

“It makes a lot of good sense not to be drinking your calories in the first place once you can move to actually eating your calories.”

“Food is not a narcotic, it is not a sedative … and here, you’re using food to put someone to sleep. That’s like taking a sleeping pill. You’re using it as a narcotic. That’s not a good use of food or calories. And that’s not a good habit to get into in the first place.”

Furthermore:

“A child who is breastfeeding is in control and drinks until he’s full, whereas control is with the parent when a child is bottle-fed. Even if the child is satisfied and pushes the bottle away, a caregiver might continue insisting that it be finished.”

Importantly, however, I also noted that a longitudinal study, although revealing findings that are highly plausible, should not be taken to prove causality.

Nevertheless, given the strong biological rationale based on what we know on neurodevelopmental aspects of ingestive behaviour, I would not be surprised if similar associations are found in other birth cohorts and that future intervention studies (although hard to do) may well prove that denying kids the bottle after age two may reduce the risk of future obesity.

It should also be noted that although this study found a 33% increased risk of obesity at 5 1/2, this comes nowhere near the 300% increased risk of obesity associated with less sleep found in the Quebec Family Study.

There will never be one thing that fully explains obesity in everyone – not unlike genetic risk, each single factor can be a small piece of the puzzle – impacting some folks more than others.

The more we understand this, the better (some would say the only) chance do we have to deal with this issue.

AMS
Toronto, Ontario

Gooze RA, Anderson SE, & Whitaker RC (2011). Prolonged Bottle Use and Obesity at 5.5 Years of Age in US Children. The Journal of pediatrics PMID: 21543085