The body mass index is a commonly used measure of body size. It’s calculated by dividing someone’s weight in kilograms by the square of their height in metres. It looks kinda ‘sciency’, but actually it’s a quite useless measurement, principally because it takes absolutely no account of the body’s composition nor the distribution of fat in the body.
I was reminded of the uselessness of this measurement this when a mother brought her 12-year-old daughter to see me in practice. In November, the mother had been sent a letter from her daughter’s school which informed her that she was too heavy, and at risk of health issues as a result.
Her parents thought this was quite mad, and just eye-balling the daughter led me to the same conclusion. Even the most cursory of glances told me there was nothing about this child that could remotely be described as overly fat.
Both the mother and daughter told me that the letters sent out by the school had caused many children at the school to become weight-focused. I wouldn’t be surprised if already some of those children are starting to have body image concerns. It was clear that the daughter had become somewhat insecure about her eating habits (she ate a generally very healthy diet, by the way) and the impact this might have on her weight.
I asked the daughter how she had felt before the letter. It was clear that up to this point, she did not perceive that there was a problem.
So, why did the mother bring her daughter to see me? Her mother thought the classification of her child as overweight was quite mad, but wanted this opinion supported by an independent health professional (me). Basically, her mother wanted to do what she could to put her daughter’s mind at rest. I do genuinely hope I managed to do that. He daughter did seem genuinely reassured after our chat.
After the consultation, I remember reading about similar stories in the press. Here’s one such story.
Screening programmes of this nature may look very worthy on the outside, but they clearly fail some people (like this girl and her parents). It reminds me of the limitations of screening generally. As we’ve seen with, say, mammography and prostate cancer screening, some people will benefit, but overall these interventions are simply not very effective. Plus, they massively increase the number of people who have a diagnosis and may then endure unnecessary, debilitating treatment, never mind the emotional distress that often comes as part of the process.
Has anyone actually assessed the impact of the screening for ‘obesity’ in children? I can’t find any relevant evidence. I wouldn’t be surprised that if it was studied formally, it would turn out to be, largely, a waste of time and resources. One thing I know for sure is that this initiative is causing unnecessary stress and worry in some children, and this can’t be a good thing.
Hi John. I certainly agree with your comments on BMI. In my medical practice I have measured over 18,000 body composition readings and I guarantee you that the percentage of fat in most patient’s bodies correlates very poorly with both weight and BMI. If you lose 10 pounds, it certainly makes sense to know exactly what you lost. Was it 10 pounds of muslce? Was it 10 pounds of fat? Or perhaps some of each. I find it amazing that the “experts” who tell us to use BMI fail to think logically or scientifically.
I usually advise patients to take body measurements or pay attention to how clothes fit. When you lose fat, you tend to noticably shrink–when you lose muscle, not so much.
Why did the school think the girl was overweight, I’m used to athletes confounding the BMI charts but why would a twelve year old?
That is a little strange as she is only 12. I am not sure what to think about this.
What use is it in advising a child she is overweight and reinforcing this as a sterotype that all big people are fat, this has to have an impact on the childs self esteem. If the BMI is being used then surely then this should be challenged as an unscientific means of measuring fat and health. Is BMR, a better method of delivering a health index?
I totally agree with Salim. What negative messages to be giving children and their families. BMI measurements would appear to be pretty useless for adults and seem not advisable, or applicable for children. Is it advisable to dwell on weight or appearance and use words and numbers that refer to size and shape? Weight loss diets are not for children – I wonder what advice the children and families will be given – portion control – low fat – REALLY? We are talking here about growing children – physical growth, intellectual, mental, emotional and social development. Children grow and mature at different rates (I know this from my own two sons) height can get ahead of weight or vice versa. Children store extra weight, I understand, before a growth spurt. This is normal and helps support rapid growth. Plus we all do come in a variety of shapes and sizes – genetics will be a part of this. Dr Briffa is right it seems to be that this has the potential to cause a lot of stress to children and their families without really addressing the problem of obesity in young people. Preventing obesity is important but so is preventing distorted body images in children at a very vulnerable age.
Ha! I work at a preschool and these children are already being measured at 3 and 4 years of age. There are also children as young as this that are already starting to form body images in their minds….at 3 and 4!!! Papers are sent home to the parents about their children’s weight and BMI.
Alice Waters started a movement in the USA to reconnect children to nature – to learn by doing things. This is an extract from her book ‘Edible Schoolyard’
‘….how a school principal, students, and parents made something beautiful happen in a blighted place. …..where children join their science teachers in growing and harvesting brandywine tomatoes and golden raspberries along the way to learning about biology, ecology and chemistry. Inside is a working kitchen…… and it has a communal dining table where many of our students eat the only shared meal of the day, and where the civilizing rituals of the table have become part of the larger curriculum. By the time a young girl has finished a delicious meal and returned her table scraps to the garden soil, and gone back to planting and harvesting with her science class, she is well on the way to understanding the cycle of life ….. absorbing almost by osmosis the relationship between the health of our bodies, our communities, and the natural world’
http://healthyschoolscampaign.typepad.com/healthy_schools_campaign/2011/06/spotlight-on-healthy-eating-food-for-life-partnership.html
The above link is also interesting and highlights a similar movement in the UK the ‘Food for Life Partnership’ There is so much that can be positively done in schools. We perhaps all remember a teacher that made a difference to our lives. Many children seem to think that ‘food’ comes from supermarkets. We know sadly that a lot of what is aimed at children in supermarkets is not
‘food’. Children learn by doing. Maybe that would be a more positive way to attack obesity problems in young people – good food that is grown respecting the soil and welfare of animals and that is healthy for our children to eat is an academic subject.
Considering the rise in obesity and incidence of Type II diabetes in children, I can understand why some school officials thought it might be a good idea to inform parents that their kids’ BMIs were higher than the “normal” range. After all, eating habits and attitudes toward regular exercise are often ingrained at a young age. However, if school officials are going to come out out so aggressively with the BMI numbers, they should also provide some education on interpretation of the BMI, particularly on instances in which it does not accurately reflect a “healthy” weight. On a separate note, there should be some sort of long-term study conducted to see whether such BMI screening at the grade school level (and earlier) has the intended effect of decreasing the incidence of obesity and Type II diabetes as the kids grow up. Obviously, it wouldn’t make sense to perpetuate these practices if they aren’t effective…or worse…cause harm in the children by giving rise to self-esteem and body image issues.
Having had 4 children, 3 of whom are now adult, I know that around 12 years of age children do get that ‘puppy fat’ which seems to act as fuel for the growth spurt that follows soon after. My kids turned from skinny to slightly ‘fat’ and then turned into the beautifully formed adults that they are now. It’s a very dangerous age to start to make them concerned about body image – girls need to be of a certain weight for their periods to start – my youngest, who is 14, was reassured by her 2 older sisters that she’d be fine in a year or so.