Posts Tagged ‘ BMI ’

Should Schools Calculate – And Share – Your Child’s Body Mass Index?

Thursday, September 5th, 2013

Schools in 19 states are calculating each student’s Body Mass Index – BMI – and sending the information to parents. The point, of course, is to inform parents if a child is clinically obese – or getting to that point. 

There are a number of opinions about this practice. Elisa Zied has illustrated – in her The Scoop on Food blog – the pros and cons of this approach as a method for combating childhood obesity. We know we need to do something to bring down rates of obesity in kids. But is this approach worth pursuing?

I suggest it isn’t.

The reason is that providing information without suggestions for change is typically not influential. I attended an early childhood summit at the Boston Children’s Museum last spring, and it was clear that public health experts believe that parents need strategies for handling a range of complex issues that face them and their kids rather than facts and figures. Simply telling them that their child is obese, without providing real support and ideas for changing that picture, will probably not do much at all. And some worry it will only encourage poor self-image. Look at it this way. If a child is doing poorly in school, the report card that gets sent him lets the parent know that. But without any information about why the child is doing badly (Is the material too hard? Do they need a different study routine? Is there a possible learning disorder? Are they goofing around in class too much?), and without conversation between the school and parents about the next steps, that information does not typically lead to a solution.

Schools do have the potential to educate and influence parents as well as their kids. Rather than sending home a BMI score like it’s another grade, it would make sense to consider educational programs for parents and kids that take on the causes of obesity. They could share strategic information such as the types and amounts of food kids should be eating – and illustrate the caloric realities of fast food. They could provide suggestions for parents who are struggling to buy healthy foods because of the costs – and give them some real options for changing their kids’ diets. Genetics is part of the cause for some – some kids are just more prone to putting weight on easily – and the reality of that should be discussed. More information about how much exercise kids need – and how they should get it – should be part of the mix.

I’m not saying that schools should do this. But I’m saying that if schools want to play a meaningful role in combating childhood obesity, they will need to do much more than just providing a BMI score.

Body Mass Index via

Add a Comment

Is TV Viewing The Unhealthiest Screen Time For Kids?

Tuesday, April 9th, 2013

A new study published in Pediatrics suggests that it may be, at least when it comes to risk for obesity. 


91 teens (45 girls) around 14 years of age responded multiple times a day – via an electronic diary – to questions about what they were doing, over a 1-week period. Included were questions about a variety of screen time activities (for example, TV, video games, computer) and how much attention they were paying to each activity. Electronic diaries are an excellent method for getting kids to report on what they are doing in “real time” – it’s quick and easy for them to do and studies have shown that they provide reliable data using this method. The kids also had their height and weight measured by the research team in order to calculate their body mass index (BMI) – which is one metric used to measure risk for obesity.


The overall findings were intriguing. First, the raw amount of screen time reported by the kids was not associated with their BMI. The statistical association of interest involved TV, but again it wasn’t about how much TV the kids were watching. Rather, it was how engaged the kids were when watching TV that was associated with BMI – the more a kid reported that they were paying the MOST attention to TV (versus all other activities), the higher their BMI.


There are limitations to the study design that need to be addressed. The most prominent is that each teen was only observed during the 1-week period (this was a “cross-sectional” study).  Finding statistical associations in a cross-sectional design limits what we conclude because we can’t tease apart what leads to what.  It could be that kids with the highest BMI levels were the most likely to become engaged in TV viewing. It could be that TV viewing was one of the causative factors for their increased BMI levels. The point is that with these kinds of data we can’t distinguish between those interpretations. And of course we don’t have data on younger kids from this study, so technically there are no inferences to be made on non-teens.


Noting the limitation discussed above, researchers use cross-sectional data to generate and support hypotheses to be tested in future studies. The interesting idea that comes out of this paper is the speculation on the specific health risks associated with TV viewing versus other forms of screen time. One deserves particular mention. They note the potential impact of commercials promoting unhealthy foods – which may be particularly influential for kids who are highly engaged watchers. What’s interesting here is the idea that it’s not just about screen time, and it’s not just about TV – it’s about the specific risk of being a highly engaged TV viewer that seems to be linked with BMI. But future work will need to measure all these things and evaluate them longitudinally.


Clearly this paper is the beginning, and not the end, of the story. The story, however, may be quite informative for parents if future studies replicate and expand the finding – and particularly if longitudinal studies provide clearer evidence of the directionality of the findings and support for the hypothesized mechanisms. Starting with younger samples of kids and tracking them across time will help determine if engaged TV viewing is especially linked with increases in BMI. But right now the interesting idea for parents to think about – at all ages – the potential downside of when kids get too attached to passive activities. This study suggests that TV may be the worst culprit for multiple reasons. But the bigger picture is that we are probably moving away from talking about screen time per se – many kids are increasing rather than decreasing screen time – and shifting toward a focus on unhealthy habits and unhealthy content that may be linked with specific types of screen time.

So … right now keep on eye on when your kid seems most likely to pair eating with screen time, and see if you can discourage that link. And see for yourself at home if it seems to happen more when they are especially glued to the tube.

Remote Control and Salty Snack via

Add a Comment

Sleep Loss And Fat Gain: The Link Between Two Childhood Epidemics

Thursday, June 30th, 2011

In my last post, I referenced new evidence confirming that children today suffer from a severe sleep loss compared to previous generations. One reason for concern is that new studies are showing how lack of adequate sleep in childhood leads to increases in body fat — which is a first step toward risk for type 2 diabetes (another related epidemic) as well as heart disease.

What’s especially troubling is that this process starts early in life. Two new studies have used longitudinal designs to show that short sleep (less than the minimum recommended amount of sleep for a given age) in toddlers leads to increases in body fat at age 7. In one report, consistently short sleepers at age 2 were shown to have a higher fat mass index (FMI) at age 7. Another paper showed similar findings linking short sleep at age 2 to increased Body Mass Index (BMI) at age 7 — the authors concluded that extending sleep by an additional hour per night would lead to a significant decrease in BMI reflecting a reduction in fat deposits. Importantly, both of these studies accounted for a number of confounding factors that could have skewed the results, suggesting direct links between sleep loss and fat gain.

Why is this information so important for parents? A third study has taken the research a step further by demonstrating that short sleep is linked with direct changes in body functioning, such as altered insulin levels, that signal early risk for type 2 diabetes. This report also suggested that inconsistent amounts of sleep from night to night was also bad for kids’ metabolism on top of the effects of short sleep. And there was one more important take-home message for parents:  a little catch-up sleep on the weekend was a good thing for kids and helped protect their bodies from the effects of short sleep.

As a parent, I know first-hand that regulating a child’s sleep is not easy (and sometimes becomes very hard). But putting as much effort into this as possible — especially in terms of making sure minimum sleep requirements are met consistently — can have an important positive effect on your child’s health and well-being.

In my next post, I will take on the issue of sleep methods, and provide a surprising perspective on how to determine the best sleep method for your child.

boysleepingImage by photostock via

Add a Comment