Does anyone understand kids bmi?

[IckyPlush]

DD (5) has just been measured as part of some government program for reception classes. She was 97th centile and apparently this means she has a high bmi and is obese.
What I don't understand is this
A) she was 98th centile for weight and 95th for length at birth and has stayed pretty close to this ever since
B) she's very active, dance, karate and rainbows as after school activities and walking/ cycling with us at the weekend. She can walk 4 miles easily
C) the letter that came home focuses on her weight, how she's too heavy but she's also 'too tall' as in 97th centile height, tallest girl in her year but that doesn't get mentioned
D) she's pretty much the same height and weight as her 8 yr old cousin, who has an OK bmi. If it's based on height/ weight why the difference?

Can anyone explain it? Should I be worried or not?

[AugustRose]

Has it given you the actual height/weight measurements rather than just the centiles? It would seem odd to include weight but not consider her height. This is the NHS BMI calculator you could use to get your own idea.

www.nhs.uk/Tools/Pages/Healthyweightcalculator.aspx

I suppose the difference is that an 8 year old will have a bigger bone mass than a 5 year old. My DD (14) is the same height as me but if I weighed the same as her I would be classed as very underweight yet her bmi is in the middle of healthy.

I remember when my DC were younger the HV worked on if there was a difference of two or more percentiles between weight and height than the child was overweight.

[milkysmum]

She is 5, please don't be worried. If she is generally fit and healthy which it sounds like she very much is I would completely disregard this letter!

[AugustRose]

Meant to add, 3 of my DC were chubbies until the got to school (not saying your DD is) but now they are all skinny things - I think school dinners put them off

[SevenSeconds]

As they get older, it is generally considered more useful to calculate BMI rather than separate height / weight percentiles (because BMI allows for both in one number). You say the letter doesn't mention her height, but if she's 97th centile for BMI then they have taken her height into account. If you use the link that August gives above you will need to enter her height as well as her weight.

She sounds like a healthy, active girl and BMI for children can be misleading, but I wouldn't ignore the letter completely. I'm absolutely not suggesting you put her on a diet or anything, but maybe think about her typical eating habits and whether there are any simple ways you could cut down on sugar intake.