Does Extended Bottle-Feeding Really Cause Obesity?

Even though she’s now 23 months old, my daughter Maya still really likes hitting the bottle. It’s a ritual—the first bottle of the morning, and a request when I get home from work. She sits on my lap, we cuddle, and she relaxes, her body growing less tense. In the evenings, I don’t give her much because it will ruin her dinner. We both know it’s the pose that matters, and that little time for reconnection.

So of course I was immediately concerned when my pediatrician abruptly told me to stop using bottles “cold turkey” because they are linked to obesity. She was right that a new study from last year connected bottle usage to obesity, and it sure made for some frightening headlines when published, like this one: “To Avoid Adult Obesity Stop Bottle-Feeding at 18 Months,” from Medical News Today. The article began by intoning darkly:

If you want to reduce your baby’s chances of becoming an obese adult you should not continue bottle-feeding him/her beyond 12 to 18 months.

Who wants a fat kid, really? Or this one, from U.S. News, “Prolonged Bottle Feeding Boosts Kids’ Obesity Risk,” which began:

Nearly one-quarter of 2-year-old bottle feeders were obese at age 5, researchers say.

Well, I suppose that seems clear enough. But what did the research really say? Here’s more detail:
The prevalence of obesity at 5.5 years was 17.6, and 22.3 of children were using a bottle at 24 months. The prevalence of obesity at 5.5 years was 22.9% (95% CI, 19.4% to 26.4) in children who at 24 months were using a bottle and was 16.1 (95% CI, 14.9% to 17.3%) in children who were not.

Prolonged bottle use was associated with an increased risk of obesity at 5.5 after controlling for potential confounding variables (sociodemographic characteristics, maternal obesity, maternal smoking, breastfeeding, age of introduction of solid foods, screen-viewing time, and the child’s weight status at birth and at 9 months of age).

I was struck by several things here. First, although nearly 23 percent of bottle-feeders were obese at the age of 5 1/2, 16 percent of the rest of the population (i.e., not bottle users) also were, which is only a 7-point difference.

Second, the sample size is on the small side — i.e., 22 percent of the sample used a bottle, 23 percent of whom ended up overweight. That’s a total of 341 kids. If we subtract the 16 percent that represents the background obesity rate, there are only 55 kids whose habits are driving the conclusions (because they make up that 7-percent spread). The authors say that is a statistically significant number, though, so I also took a gander at their assumptions.

They used a data set with limited inputs, certainly. First, the study did not account for what was actually in the bottles. Yet it seems to me that this could matter a lot. Apple juice, for example, is high in calories and does not fill you up, yet creates a taste for sugary drinks, making it easy to consume to excess. While whole milk may be higher in calories, it offers a host of essential fats, vitamins and calcium, and is denser and harder to over-consume. Water, obviously, has no calories. Formula, which is loaded with sugars that stimulate appetite, unsurprisingly is also linked in previous studies to obesity.

As children are frequently given juices (or even worse, Kool-Aid), given the small number of families driving the conclusions, this seems like an important caveat, and one notably missing from the official conclusion or coverage. Instead, the authors publicly suggest the opposite, where one of them claims that the study accounted for “feeding practices during infancy.” But this is misleading. After all, what a child is actually consuming has just got to be more important than whether it’s being delivered by bottle or cup.

Second, the study did not measure the kind of bottle being used, whether glass or plastic. Before you think I’ve gone off the deep-end on this one, consider that studies have shown that Bisphenol-A (BPA) likely plays a significant role in obesity, both by making our bodies produce insulin as though we are consuming twice the calories we actually are, and by helping to flip a genetic switch that predisposes us to be fat.

The study’s data-set spans 2001 to 2006, when most parents were unaware of the BPA issue and most bottles still had BPA in them, and in which plastic bottles were typical, as they are today. But the analysis simply ignores the possibility of harmful chemical influences.

Third, the authors’ don’t recognize any benefit at all from using a bottle:

Rachel Gooze notes that weaning children from the bottle by the time they are 1 year of age is unlikely to cause harm and may prevent obesity.

I beg to differ. Research shows that strong bonding is essential to healthy brain development, particularly in children ages 0 to 3 years. While extended use of a bottle is not an essential part of creating these bonds, the act of feeding a child is intrinsically a nurturing moment, and so it may not be irrelevant either. The researchers should have at least considered the possible emotional downsides.

For our family, my daughter never breastfed, and so our bonding over a bottle has replaced a rather fundamental missing piece. I’m not eager to let this go based on one study showing she could, maybe, have a slightly greater chance of being obese four years from now, especially given the care I take with her overall diet. For example, she almost never has juice, or really concentrated sugar of any kind.

If using a bottle appeared to be causing cavities or hampering her speech development, that would be another issue, and is a legitimate concern raised by dentists (those sugary beverages again!) and speech pathologists. My daughter now uses (I would guess) about 600 words and more every day. She’s also never been very interested in a pacifier or thumb-sucking, either of which can also be a speech development blocker.

Moreover, she eats a wide variety of fruits, proteins and vegetables, uses both sippy cups and regular cups, and is learning to use a straw, as speech experts advise. The bottle is just a break, and I assume will drop away sometime when she’s no longer needs that daily form of checking in. If not, we’ll ease it out of use and replace it with some other bonding ritual we invent.

In the end, I’m not convinced at all by this study, and disappointed that both my pediatrician and the press apparently take its conclusions as gospel. Advice from doctors rarely seems to take account of the havoc that would be wreaked on families’ lives by following their rigid approach. The costs of this in terms of both family peace and pediatric credibility are high. And the concerns around obesity have now reached such a fever pitch that it seems we’re able to be bossed around on “slim” evidence indeed.

It seems to me we all would benefit from trusting our instincts about what’s right for our child–for others besides my daughter, taking the bottle out of circulation may be no big deal. For the rest of us, we probably just need a moment or two to relax in a day, and so do our kids.

How does your family come down on this issue? Am I just making up excuses because I don’t want to face the music (or really, screaming)?

Did I miss something important about the study or its implications? Or do you agree with me that this is just another in a too-long line of simplistic anti-obesity messages that fail to grapple with the real issues?

Laura MacCleery is a non-profit lawyer, mom and squeaky wheel in search of a spoke. Read more of Laura’s writing on her blog, Laura’s ‘Rules’.