How much weight did your child lose? Weight suppression is critical in eating disorder diagnosis and treatment

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 it's low, or if the person looks emaciated, everyone agrees that medical and mental risks need attention. There's a full assessment, monitoring and treatment.

But the same needs and urgency may apply to someone –especially a child or adolescent — who's lost weight, or failed to gain weight.

This is where the concept of 'weight suppression' can help:

• if your child lost weight, that's weight suppression
• More surprisingly, to some: if they failed to gain weight as expected (for their age, or to match a growth spurt) that's also weight suppression. Some call it 'falling off their growth curve'.

The degree and speed of weight suppression is predictive of a person's risk from malnutrition, and of the severity of their eating-disordered mental state.

With weight suppression, you need specialised guidance on nutrition, weight, and if you have eating disorder symptoms, you need eating disorder treatment.

What you don't want is for a clinician to only look at current weight or BMI and declare that all is well.

I say more on my page on 'atypical' anorexia.

Your child weighs the same as last year? That's weight suppression

Here's an illustration of the issue if your child weighs the same now as last year. In terms of their body's needs, they have lost weight. That's because over the course of one year, a teen is expected to gain weight:

* 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 from 'overweight'? That's weight suppression

If your child has lost weight, that's weight suppression — even if they're now a 'normal' weight.

Tell your clinician your child's weight history, so that they don't just look at their current BMI. They need to know about the amount and speed of suppression.

There is of course a risk that a clinician will congratulate a child for dropping down to the 'normal' range. We're so used to the flawed message that BMI and health are the same thing. If that happens, look for someone with more expertise.

The amount of weight loss, and the speed of weight loss

Whether or not your child 'looks normal', if they're weight suppressed, their body could be malnourished and in need of medical attention — urgently in some cases.

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

Weight suppression is relevant to anyone diagnosed with 'atypical anorexia nervosa'. These are the individuals who restrict and lose weight, and maybe because they started off quite heavy, by the time they show mental and behavioural symptoms, their BMI is in the 'normal' range.

Weight can also be 'normal' because you, the parent, are doing a great job of keeping them steady.

What matters there is the full picture, including the degree and rate of weight suppression.

Read my post on atypical anorexia nervosa to get yourself well informed of the issues.

Should you calculate from the highest ever BMI?

Like everything to do with weight, we get into trouble when we try to be mathematical and apply one-size-fits-all rules.

Weight suppression is the gap between the weight a person used to live with, and today's weight, right?

But… should that be the highest-ever weight (or BMI) they ever reached (highest 'premorbid' weight).

This doesn't distinguish a brief peak weight from a stable sustained one.

Weight restoration

Why does the above matter? Because some assert that recovery from an eating disorder requires all the weight to be regained.

I'm thinking of all the parents I talked with shortly after Covid, whose child had gained a lot of weight during the lockdowns, and then dieted, exercised and had a dramatic drop — and required urgent eating disorder treatment.

When you're trying to work out what a body needs, should you look at that very top figure, or at the growth curve the child tracked on outside this unusual time?

Some people are concerned that if all the weight isn't recovered in treatment, a person stays weight-suppressed, and that this will maintain the eating disorder.

They believe that a person won't recover unless they reverse all of the weight suppression. Regain all the lost weight. Get back to the highest percentile they ever reached on their growth chart, even if it was only a brief peak.

Some assert that weight gain always needs to go beyond premorbid levels — that an overshoot is essential.

I've looked for published evidence for any of this, and I don't believe there are any such simple, universal recipes for recovery. There are personal experiences which point in either direction.

To be clear, what this does not mean is that your child can stay malnourished.

I recall a mother telling me of the most extreme signs of anorexia in her teen, including an obsession with recipes and cookery programs and watching others eat (which to me, indicates unsatisfied hunger). This girl had lost a huge amount of weight over just a few weeks. Yet the treatment was just this: her BMI is normal now, so just follow this 'weight maintenance' meal plan. Definitely not good enough, in my view.

Your child must to be followed through nutritional rehabilitation and all aspects of eating disorder treatment. It's doubtful that any competent expert can make an accurate prediction of your child's 'weight recovered' number.

What's for sure is, if there's weight suppression, your clinicians need to take it into account.

My main page on weight restoration
* Weight-restoration: why and how much weight gain? *

and also:
* 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