In a well-meaning attempt to improve the health of our nation’s children, Michelle Obama took Americans into her daughters’ pediatrician’s office. A few years back, she recollected on the Yahoo “Shine” website, their doctor warned her the girls’ BMIs were edging up. In other words, they were getting fat.
“I certainly didn’t know that even a small increase in BMI can have serious consequences for a child’s health,” Obama confessed. The doctor urged attention to the quality of the girls’ diets, an appropriate health consideration for any patient. But why would he need to know a child’s BMI before advising her mom to switch from soda to water? Should thinner children just drink the sugar?
Like most nutrition scientists and physiologists, I salute the First Lady’s ambition to help. Her “Let’s Move” program advocates many basic, low-cost lifestyle changes that could improve kids’ lives and health. Encouraging veggie plots in schools? Great. A model organic farm at the White House? Love it! Advocating for more parks and phys-ed classes? Brava.
But, basing health care on routine BMI testing from the age of two? Bad—bad science, bad medicine, bad idea. So long as it’s framed around “ending obesity,” the otherwise admirable Let’s Move initiative is doomed to fail. “Fighting fat” for its own sake is futile and lacks scientific basis.
There’s ample peer-reviewed evidence that eating and exercise have far more impact than weight on individuals’ health status. And that social injustice may trump them all as a health deterrent. Moreover, for all we know, fat may actually provide us with some protection: the Centers for Disease Control mortality analysis, consistent with the bulk of research on the topic, shows “overweight” people actually outlive those in the “normal” BMI range.
The White House recommendation of BMI as an exam-room benchmark would place doctors on the cutting edge of statistical medicine—circa 1850. That’s when a Belgian astronomer first conceived the height-weight ratio. BMI has its uses for aggregate population studies, but as an individual diagnostic tool, it boasts all the predictive utility of discredited standbys like cranial measurements and the Four Humours. Proving just how arbitrary BMI-based categories can be, the National Institutes of Health adjusted its “normal” range downward in 1998, causing about 35 million Americans to “become overweight” overnight. They set the cutoff for overweight at 25 and for obesity at 30, yet the only relevant peer-reviewed research they cited didn’t find a statistically significant relationship between BMI and mortality until BMIs in excess of 40. Raising the standards would have been a more astute application of the science.
The BMI back story is even more pathetic when applied to kids. Cutoff points for “overweight” and “obesity” were arbitrarily assigned based on comparison to what kids weighed a few decades back, without even the pretense of considering health data.
Let’s Move’s fat-focus fails by inserting bogus BMI numbers and body-size bias into what is really a dialogue about health. Yes, many Americans of all ages eat too much that doesn’t nourish them and too little that does. As Ms. Obama rightly notes, our children are more familiar with fast food than family dinners and spend too much time watching screens. But the danger in all this isn’t fat; it’s disease. And the goal is not creating thinner citizens, because thin people get sick, too (and don’t necessarily enjoy lower mortality).
BMI testing is worse than ineffectual – it’s damaging. The last thing kids need today is more body shame in a culture already hung up on celebrity waistlines and skeletal fashion templates. As a teen recently asked me at a school with an active obesity prevention campaign, “Don’t they understand how it feels to walk through the halls and be confronted with signs that say, ‘we don’t want anyone to look like you’?”
Fitting into size-4 jeans confers little protection from body anxiety, either. Most thinner people also struggle with their weight demons. Whether from Let’s Move or The Biggest Loser, the “Be thin!” message hurts us all.
Obesity alarmism impedes sound medicine in other ways too: People of all sizes deserve evidence-based care and remedies that, unlike weight-loss advice, are proven to work.
Why let size bias and its damaging rhetoric undermine the best of Ms. Obama’s potentially powerful leadership on health? Instead, “let’s move” forward using sound science, without the BMI bugaboo and obesity distractions. By encouraging healthy behaviors for their own merits, rather than to fight fat, we can help children of all sizes and shapes achieve happier, healthier futures.