Does any SDoper know if the recommended BMI rating is different for kids than adults? One would think so, but if you go by Wii Fit as a source, it does not seem to account for any difference…and yet their recommended BMI for my kid makes no sense! What’s the real BMI recommendation here?
Bonus Question: Can one really be “big-boned”, or is that just an excuse for being fat?
Here is a good link on BMI for kids and teens from the CDC.
I reckon people can be big boned. If I look at my GF’s wrist and mine, for example, an area where there’s very little fat so you can say the size difference is bones, not fat, hers is much bigger than mine. Her hips are also wider even if you just measure from bone to bone.
Wii Fit does use different words for the kids’ part, at least. I do wonder if maybe it is adjusting for age, because that could explain why my daughter is at the top end of the ‘good’ bit - she’s eleven and has a body like a grown woman, and they’re not expecting that on an eleven year old, so assume it’s fat. If you wait a while. however, the Wii Fit does eventually notice that the kid’s height has changed and prompt you to update your profile, which I think is quite 
.
The standard BMI calculation is generally understoond not to be accurate for children and they jumped through hoops deriving formulas that can be better used for children of different ages and teenagers. I don’t know why they bother. Calipers are a more accurate measure of body fat, and ‘thin’ people can easily be overfat by percentage.
Absolutely people have different size skeletons and that has a huge effect on people’s weight. I have a small, narrow frame and look like a child next to most grown people.
At 5’5" I have 5" wrists and a balanced figure at 31-23-33. My BMI has always been significantly underweight. I am healthy as a horse and have a normal body fat percentage as tested by calipers.
My boyfriend to pick just one example has pretty large bones and his BMI is verging on overweight - but he doesn’t have extra fat, and isn’t super-muscular. He’s just sturdily built. Most people describe him as ‘thin’ or even ‘skinny’.
Just looking at us two I can see that BMI is a bullshit indicator of body fat percentage or a ‘healthy weight’. If BF lifted some weights he could easily get to an ‘obese’ BMI without looking like a bodybuilder. And I would look fat at a much lower BMI than most adults.
What you say makes a lotta sense and I don’t disagree. Still, I think part of the reason that various 'health organizations" emphasize BMI is that people can measure it (and track it) themselves. There is a lot to be said for involving people in maintaining their health as I’m certain you’d agree.
Another big problem with the BMI (and possibly calipers too, I’m not sure) is that BMI fails to take into account where in the body most of the fat is. Specifically, femoral-gluteal fat does not correlate with the various markers of the so-called ‘metabolic syndrome’ such as dyslipidemia, hyperinsulinemia, dysglycemia, etc. Neither, AFAIK, does a high BMI due to large amounts of fat in such a female or gynecoid distribution correlate to harder endpoints like heart attacks.
My 14-year-old daughter scored 25.8, 90th percentile, “overweight”, on the CDC kid calculator site. She is absolutely not overweight. She is very athletic and fit, with a swimsuit figure any of her friends would envy. Evidently her muscles are very dense. My husband has the same situation on the adult scale. He’s tall and lean, but works out every day and always scores as being overweight. I ignore the BMIs.
I kind of figured BMI was BS after seeing what numbers get assigned to several people I know.
What’s the research say about this? Are experts in physiology, medicine or nutrition saying it’s an accurate measure of something useful?
Here’s a photo of her from 7 months ago. She weighs about 7 lbs less now.
I’ve found that for the young flodnaks, who have both been very tall for their age basically since birth, the best indicator has been the weight-for-height chart. NOT the weight-for-age chart, which is useless for kids who aren’t close to average height, but specifically weight-for-height.
BMI is a horrible measurement in general. I’m pretty short (170cm) but wide shoulders and very dense muscles. According to my BMI I’m badly overweight. In fact, the only way I could lose enough to get to the lower end of the “normal” scale is muscle atrophy.
My understanding is that BMI measurements are a fairly good, albeit rough, predictor of various health conditions, disease risks and mortality over a population. However, it may not be so accurate per individual like, for example, one who works out a lot and has atypically high muscle mass.
Personally, from most of the people I know, the normal range of body mass as predicted by BMI seems about right. But there are outliers–I can think of one or two people where I’d say the normal range is off by about 20-30 pounds.
I just went over this in detail with my 11 year-old son’s doctor. I’m quite concerned about his weight- he’s beginning to look like a mini Michelin man here… and I brought up BMI. His doctor did go over it, but also showed me the growth charts, with percentiles and everything, and that’s much more comprehensive. Seems that what really matters is the personal history, the arc of weight over time, and in comparison to height, and in comparison to others their age.
Plus, he said that a lot of prepubescent boys will gain an incredible amount of weight just before puberty, and after that height gain, the weight won’t be a problem.
And yep- frames come in large, medium, and small, and that makes a lot of difference.
I think BMI is a somewhat useful measure for what it was invented for (and used for until the 1970s or so when it came into vogue as a personal fitness measure) - tracking weights across large populations. However even at that level it’s seriously flawed, because the inventor of the BMI calculated his body norms from armies. The idea that the body weights of fit young soldiers under the age of thirty can tell us anything about what is normal or healthy for all human bodies to weight in proportion to their height is absolutely ludicrous.
Another problem is that people with ‘ideal’ BMI (19-25) are put in danger by using BMI as a measure of body fat or health. ‘Thin’ people so often assume that since they are not-fat, they are at low risk for diseases correlated with being overweight. But many slim or normal weight people have dangerously high levels of body fat (often abdominal deposits that may not even show externally as a ‘belly’, but nonetheless are a big health risk), due to poor diet and lifestyle choices, and body fat percentage in particular abdominal fat, not BMI, is what determines risk for metabolic syndrome and cardiovascular disease, etc.
This is absolutely true. My hubby is one of three boys. Their Mom has all their school pictures lined up on the wall from kindergarten to senior year. They are all normal looking (maybe even a little skinny) in all the pictures from kindergarten through 7th grade. In their 8th grade pictures (about 13 years old) they all have chubby cheeks and double chins. They look quite over-weight. The next picture (9th grade) they are thinner again (post growth spurt). It is interesting to look at.
Until you stop growing a BMI isn’t going to be as useful as it is for an adult. It’s going to be off.
There are "fat kids’ that grow into their chubbiness. Of course a lot of fat kids, become fat adults too.
Until the child’s done growing, I’d put less emphasis on losing weight, unless there’s a real health issue with it, and more interest in letting the kid eat and turning his interests to something other than food.
BMI is the worst possible way to measure fatness … except for all the others.
As referenced BMI in childhood should be followed along percentile curves according to age and gender. It also must be noted that those curves are not current percentiles, but ones from decades ago when the average child was thinner. It creates an odd circumstance in which 15% of children are in the top 5% and another 15% are in the next 10% (by the curves).
Yes, it needs to be used as part of an assessment, not instead of the assessment. Athletic children will weigh more, will often have high BMI’s, but are not fat … well usually not. Sometimes (I am a pediatrician) I have to tell a High School football player that obviously his high BMI is partly all his muscle weight, but just as obviously, not all of it. It is a marker that correlates well (not perfectly) with poorer lifestyle choices though and following it sequentially is very useful, again, as one part of the total assessment.
Calipers are clinically worthless in a pediatric population. I’m not too convinced they are all that reliable even in adults.
The Wii Fit BMI report should be disabled for kids. Well intended but a mistake. A very unreliable item.
If a bit of anecdotal evidence is any comfort, my elder boy was always slightly taller than average and slightly thinner than average until he broke his foot at the end of second grade.Two weeks of no weight bearing at all and four weeks of hobbling about on crutches did a number on him and he got pudgy. He REALLY put on weight so that looking at 3rd and early 4th grade photos he was very moon-faced and tubby.
Somewhere towards the end of the 5th grade he just started to shoot up and it was like watching a rubber band stretch. His weight didn’t change more than a couple of kilos between the 4th and 6th grade but he put on about 20cms! Now he’s 13 and totally normally proportioned.