I was recently asked an important question which I was unable to address during my breakout workshop at this year's FEAST Symposium 2012.

The question: does a child who has completed their height growth need to continue to gain weight in order to stay on the same growth percentile “line” until they are 20 years old?

A glance at an average growth chart for girls shows a flattening out of the height curves somewhere around age 15.  This is because the average Caucasian girl achieves menarche (first period) around age 12.3 and grows for about two more years before she is done growing.  This means that, around 14.5 years of age or thereabouts, most Caucasian girls are done growing -- but sooner for girls of African descent, for example.

The weight curves do not flatten as dramatically, indicating that weight, on average, can be observed to rise slightly as most girls progress through early young adulthood.  The charts are silent on what happens after that, but presumably they get flatter, though probably never entirely flat.

Once height potential has been achieved (as I say around 14.5 to 15 for the average girl whose menarche was around 12.3) AND the girl is menstruating regularly AND she is not engaging in eating disordered behaviors (such as “restricting lite”), there is, in my opinion, no absolute reason why her weight should be forced up along any predetermined channel.  What purpose would that serve?  She is normal for herself.  If, however, it floats up as time passes and she gets older, and she continues to lead a healthy, active, happy life and eats with her friends and family, then that must be seen as normal, too.

I know you are familiar with the essay I wrote on determining ideal body weight. Believe me, no one is as grateful for growth charts as I am, and few people are as aggressive about full weight restoration as we are at Kartini Clinic, but I think we have to be careful about falling prey to the tyranny of growth charts and of absolute numbers.

Let’s look at a concrete example:  a 17 year old girl who has completed puberty, who grew along the 50%tile for height and the 95%tile for weight before the onset of her eating disorder (she was 5’4” and weighed 178 lbs.).  She had always been a relatively big girl, very active, loved sports, done well in school and had normal periods until age 16 when she developed anorexia nervosa.  Prior to the onset of puberty (early-ish menarche at age 10.5) she had grown along the 75%tile but had gradually drifted up to the 95%tile by age 13.5 where she was to remain until the development of her eating disorder.  

This girl’s blood pressure had been somewhat high on her last physical (140/82), before her eating disorder-associated weight loss.  She had a family history of type 2 diabetes, high blood pressure, and heart failure in older adults (also a first cousin with an eating disorder). As her doctors attempted to restore her weight, should they have tried to return her to 178 lbs. at all costs, and encourage her parents to make sure she continued to grow along the 95%tile until age twenty (by then 185 lbs.)?  Probably not.  Regardless of one’s stance on “health at every size” (for more, see HAES) and size acceptance (I am a fan), to insist that this girl cannot be well unless she is returned to a BMI of 30, would be misguided.  Her blood pressure is already elevated and she has a family history of metabolic syndrome.  If she has normal periods, eats adequately and socially, mood is stable and she is not engaging in any eating disordered behaviors such as obsessively exercising, purging, restricting, bingeing, etc., I think she might be OK at a weight and weight percentile lower than she started, provided she did not need eating disordered behaviors to stay there.  The body (and labs) will tell you where she can rest; this is the true meaning of “state not weight”.  

It is simply not one size fits all.