Last updated on September 14th, 2023
Why does weight suppression (weight loss) matter with an eating disorder?
It's easy to put all our attention on a person's current weight or BMI. If a calculator shows BMI is very low (or if they look emaciated), everyone agrees that the risk from malnutrition is high. Everyone can appreciate how the brain is affected too. Treatment kicks in.
But there's good evidence that, irrespective of current weight, another measure provides crucial information: weight suppression. How much weight was lost — or failed to be gained through growth?
Weight suppression is more predictive of a person's risk from malnutrition, and of the severity of their eating-disordered mental state.
And when treatment ends, it's not a person's weight or BMI that matters, but whether all the weight was recovered.
I often talk to parents where nobody has asked about the extent of weight loss, nobody has looked at the history of this child's growth. All attention is on the child's current weight or BMI or 'weight-for-height'. On this page I aim to highlight the importance of weight suppression.
What is weight suppression?
If your child has lost weight, then weight suppression is the amount of weight lost.
Actually, it's more than that, because we must also consider the weight a child or teen failed to gain at a time their body is programmed to grow.
Your child weights the same as last year? That's weight suppression
If your child weighs the same now as last year, they're weight suppressed and this page is relevant to you. In terms of their body's needs, they have lost weight.
A person with an eating disorder is unlikely to recover if they stay weight-suppressed. For the wellbeing of mind and body, they must gain weight and get back on track.
* For weight, stature or BMI charts as in the above image, download CDC (american) growth charts for boys and for girls. And here are UK ones, using WHO (World Health Organization) data . There's also access to WHO and CDC charts on mygrowthcharts.com *
Note that with the chart and numbers above, my intention is only to explain a principle: alarm bells must ring if a child fails to grow. What else is going on with their behaviours, their mood? We should never expect precision from a chart. The speed of growth of any child varies over their adolescence. It does not follow the nice smooth curves on a chart. I explain this in 'Weight centile growth charts: why they can’t predict your child’s recovery weight'.
Your child's weight dropped? That's weight suppression
If your child has lost weight, the same applies: they need help to regain weight and resume their growth. The bigger the loss, and the more rapid the loss, the greater the immediate medical concern.
Of course everyone is very concerned when a person becomes emaciated. These individuals will most likely get access to treatment. That's no reason to neglect the people who lost weight but now look kind of 'normal'. They may be very ill too.
Our society — and some clinicians — think it's great when a child who used to have a high BMI is now in the 'normal' range. We're so used to the flawed message that BMI and health are the same thing.
Risk from malnutrition: the amount of weight loss, and/or the speed of weight loss
Whether or not your child 'looks normal', their body is suffering from malnutrition, and is more or less in need of urgent medical attention, if they are weight suppressed.
Of course if your child is very thin that is also an indicator of malnutrition– the point is that the reverse is not true: a child who is not thin may be malnourished. Missing this can lead to an emergency situation, or simply, to a lack of eating-disorder treatment.
From the Society for Adolescent Health and Medicine (SAMH), in the US, this Position paper (Table 3) on Medical Management of Restrictive Eating Disorders in Adolescents and Young Adults:
The degree of malnutrition may be classified as mild, moderate or severe depending on:
- Magnitude of weight loss: (e.g. 10% is 'severe')
- Rapidity of weight loss (e.g. 5% in 1 month, 10% in 6 months, are all severe)
and as you'd expect, the risk is also classified high if your child is currently at low weight (with a low Percentage of median BMI (or 'weight for height') or a highly negative BMI Z-score.)
Anorexia with a 'normal' kind of weight
Many people with anorexia don't get down to a terribly low weight. Maybe because they started off quite heavy, or because you, the parent, are doing a great job of keeping them steady. The person is then diagnosed with 'atypical anorexia nervosa'. It's a diagnostic category that the best experts want rid of, because:
- it's very 'typical'
- it's very serious
- it should be treated just the same as anorexia nervosa — and yes, that means getting back up onto one's growth curve
Read my post on atypical anorexia nervosa to get yourself well informed of the issues.
Weight suppression: no recovery without full weight restoration
Finally, anyone should be concerned about weight suppression if the eating disorder treatment team is not aiming for full weight restoration.
I'll give you an example. When my daughter was 10, the eating disorder dietitian told her, "Don't worry, we'll keep you on the slim side of normal." That means, a little bit underweight, right? A little bit less than you used to be? It made her happy for a few hours, then she got super-anxious again and fought off the next meal.
My main page on weight restoration
* Weight-restoration: why and how much weight gain? *
* My YouTube: Growth charts and goal weights made simple *
* Weight gain in growth spurts *
* Weight centile growth charts: why they can’t predict your child’s recovery weight *
* Is your child's target weight a gift to the eating disorder? *
* What do BMI and Weight-For-Height mean? *
* My YouTube: What is a BMI or '% Weight-for-Height' target, and how wrong it could be *
* Atypical anorexia diagnosis? Handle with care! *
* Experts say, "Recovery weight must be individualized" *
and more in my book and in my Bitesize audio collection