BMI doesn’t work if kids are getting fatter!?

[EasynowPatrick]

I wasn’t sure where to put this, one of my dc is looking a little rounder than I think they should. I’ve done a quick bmi check (on the quiet) and it says healthy weight. Great! However, the guide goes on to say they use centiles to calculate what is considered to be in each category, if that’s the case surely as kids get fatter (along with the rest of us) then kids who would be described as overweight by the calc 5/10 years ago become a healthy weight?

That's such a good point! I hadn't thought of that at all.

I am not sure, but what I would say is that the “healthy weight” range on the bmi calculator is quite broad. So if a child is at the upper end, and they are looking a little “round” then it might be time to examine their diet etc.

My dd is at the lower end of the healthy weight range and I do know that if she was at the upper end then, for her body shape and type, she would be a bit overweight.

@Notcontent

I am not sure, but what I would say is that the “healthy weight” range on the bmi calculator is quite broad. So if a child is at the upper end, and they are looking a little “round” then it might be time to examine their diet etc.

My dd is at the lower end of the healthy weight range and I do know that if she was at the upper end then, for her body shape and type, she would be a bit overweight.

This makes sense, BUT, the thing is that what makes someone look slim, even if they're heavier, is usually being taller, but I don't think this works for kids...? Isn't it that even a tall child who is high on the centiles for height as well as weight, so looks slim, might still technically be overweight?

My point being that relying on just looking at a child and saying they look slim or not, doesn't really work if you want it to tie in with BMI.

@Notcontent I’m not too worried yet, I think a growth spurt may be imminent. I am keeping an eye on it though.

I think the numbers come from the WHO growth charts, which are based on some kids from where in the 70s. It was updated in about 2007, I think.
But the % are based on a fixed sample. I'd suspect if you took a 100 kids from a primary in some areas in 2020, more than half would be above the 50% mark.

Is it based on fixed height and weight charts, as in not continuously updated? I think we should use charts from when children were fit and healthy, no undernourished, but before this obesity crisis started.

To be honest, I think it’s usually pretty obvious if someone is overweight. Ok - probably not with babies and toddlers. But once kids are in primary school then yes. And I am pretty sure that the BMI calculator does take height into account. I think it’s the percentile charts that do not - so with the percentile charts I think you are supposed to look at both height and weight and see how they compare.

Aaaah yes, that would make sense that it's not continually updated. Aside from our goal not being what the average now is, the work involved in doing that every year would probably be quite time consuming?

The healthy BMI range is very wide though. My DS is 39th centile and could gain 10kg and still be considered healthy at the same height. He would certainly look like he was carrying too much weight long before then. I'm the same, small build and look best at a BMI at the lower end of the healthy range.

Even if they are a healthy BMI there is nothing wrong with making some positive changes to the family diet and lifestyle.