Determining Target Weights: An Evidence-Based Approach

I thought about including this piece of research in last week's smorgasbord, but I thought it was so important that I wanted to make sure it got its solo time in the limelight.

Determining target weights in people with eating disorders has never been easy. Many doctors lowball the weight so they don't scare off the patient. Which is nice (remember the phrase about the road to hell being paved with good intentions?) but it also really twists the sufferers mind and leaves them only 90% well. No one would settle for removing 90% of a tumor just to make a cancer patient feel better in the moment, so why people are very willing to tolerate sub-optimal target weights is beyond me.

This has been an issue with me because I'm fairly muscular, and I weigh more than I look like I do (a friend described me as small but solid). So the old formulaic 100-pounds-for-five-feet-and-five-pounds-for-every-inch-over left me at a weight where I had already lost my period on the way down. I was more than happy to stay at the inappropriately low weight, not the least because I got to skip out on the monthly tampon shopping sprees. It also left me deeply entrenched in the eating disorder.

There are also other treatment providers who would provide an accurate target weight if only they knew what it was. In younger children, in those who have been sick longer, and in those who don't have growth charts, even the best physician can be flummoxed. The organization FEAST has some good information on setting target weights, as does the Kartini Clinic, and although these methods are informed by science, they are still as much of an art as anything.

But we might have a new tool to help with this. A recent study from the European Eating Disorders Review found more objective ways to help determine target weight in a study titled "Predicting the weight gain required for recovery from anorexia nervosa with pelvic ultrasonography: An evidence-based approach."

The abstract of the study summarizes the outcome of the study rather well:

Transabdominal pelvic ultrasound scanning (U/S) offers a more objective method of ascertaining physical well being by the ability to determine reproductive maturity. This study aimed to explore the correlations between the maturity grading on pelvic U/S and weight for height (WfH) ratios and body mass index (BMI) percentiles. Ultrasound studies were performed in 72 female adolescents (aged 11-17 years at intake) with AN. Scans were graded for maturity using published parameters of pelvic maturity and compared with the patient's WfH ratio and BMI percentile. In our sample was a wide variation of WfH ratios and BMI percentiles at each grade of maturity. This supports the view that arbitrary targets for weight, WfH ratio or BMI percentile are likely to be unnecessarily high for some patients and too low for others. We recommend that targets be based upon baseline pelvic U/S grading and follow-up scanning.

This study will probably need to be replicated before it can become commonplace, but I am so glad that there are now evidence-based approaches for helping to determine target weight that are more effective than a coin toss or one-size-fits-all approach.

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Katie said...

I replied to this when Laura Collins wrote about it, but basically said that it concerns me because I have friends who got their periods at dangerous low weights, right down to a BMI of 13. I don't know what a pelvic ultrasound scan would show in a person with this issue, but imagine if some people genuinely DO get actual periods at very low weights, rather than the false periods usually blamed for this phenomenon. I got mine back at a BMI of 18, but if I'd maintained my weight there I would have had to restrict and I would have relapsed. I really hope that people who get their periods at low weights are studied before this procedure is put into use.

I Hate to Weight said...

this is really embarrassing -- i don't under this. can you explain in super, super simple language?

i lost my period at a relatively "high" weight the first time around. i loved not getting my period, as i suffer excruciating cramps.

years later, my weight would dip really low, and i'd still get my period. perhaps because i was older?

Anonymous said...

I agree with the first comment -
I am not exactly sure how this works exactly, but people can still get their period at really low weights. I have been at a very low weight and still continued to have my period. I have lost it before, but in my relapse (in which my weight dropped more than it did the first time), I maintained having a period.
Maybe there is a way to tell still, but I just am not sure.

Anonymous said...

Hmmm...interesting, and even though it is certainly unhealthy to be at a weight where one cannot menstruate, like a previous commenter said- sometimes the minimal menstruating weight is still unhealthy (whether it isn't weighing enough for your bones to be strong, etc). The first time I lost my period, I lost it at a pretty low weigh; got it back a few pounds higher than that, then lost it again from being at a higher than initial period loss weight...messed with my body far too many times.
It is confusing and frustrating having a target weight being determined- from all the doctors/dietitians I've seen in the past four years, just about ALL OF them had different ideal weights for me- ranging within a 30 pound range if you can believe that (and I'm 5'2, so that is a huge range from unhealthy to too high)and it just made me lose trust in all these calculations because I felt like they were basing my IBW on statistical evidence.
Thankfully, I feel like I've found my natural weight, but I understand the importance and difficulties of determining one for those in recovery.

Kim said...

I think determining target weight in recovery is INCREDIBLY important, and often overlooked. We are all different, with different healthy weights, and I'm glad that science is starting to help out when setting goal weights. I've been at 90-ish% of my formerly-optimum weight for a number of years (give or take a few pounds). I have no idea what my new optimum weight would be...probably higher since I'm 10 years older. I haven't had much help with physicians/nutritionists setting a goal. I've always been lanky. I never fit the rule of 100-pounds-at-five-feet-blah-blah-blah. Ever. I get my period regularly, but I still sense that my body needs/wants more weight. All I have is that hunch to go on, and I'm trying to allow that to be enough.

Sarah said...

Yeah, my weight was definitely lowballed at the beginning of treatment. My team originally set a 5 lb weight range based on my weight when I had the original weight loss, then when my body just could not seem to get there again despite MASSIVE calorie intake for weeks on end, they lowered my range by 5 lbs.

There were two mistakes made by my team here:
-I was 17 when I started restricting food and overexercising. Because of this, my weight did not change from age 16 to age 19, when I lost enough weight to be considered "anorexic," so I never really allowed my body to get to an appropriate place for a late teen/young woman to begin with.
-They shouldn't have changed my weight range, because I maintained there for a few months but my estrodial stayed at a man's level.

We ended up having me increase my weight range back to the original number when my estrodial levels had flatlined for a few months. Then over the last few years, I've inched up and out of that range all together (while eating/exercising the same.)

I can only determine that this weight is my setpoint. This is where my healthy 24 year old body wants to be. Not at the weight it was at as a 17 yo.

I wish I had more guidance in setting an appropriate weight range for an ADULT, because it was very challenging for me last year as I realized, "I'm completely out of my 'healthy' weight range! GASP OF HORROR," even though I'm still at a very healthy weight range and BMI. I sought nutritional counseling from a new dietitian and she was shocked at how low my "healthy range" had been before. There needs to be consideration not only of previous weight, but of previous methods of weight CONTROL when setting standards.

I have found a lot of comfort in Laura Collins' writing on this because on the age/growth chart, I am right where I need to be.

Cathy (UK) said...

To address Katie's and Sarah's questions about menstruating at a very low weight (usually BMI < 17-18): This is very unusual unless:

1. A woman is taking an oral contraceptive (birth control) pill containing oestrogens and progestagens, or usuing certain forms of HRT. Giving hormones exogenously in this way will create 'false' periods which do not represent an ovulatory cycle (i.e. functioning ovaries) - merely a withdrawal bleed when circulating hormone levels (especially of progestagen) fall.

2. A woman has already been pregnant - especially if this a full term pregnancy - which seems to reduce the risk of developing hypothalamic amenorrhoea in response to energy deprivation.

Generally, to have a normal ovulatory cycle it is necessary to have sufficient energy stores in the form of body fat, and to be balancing energy intake and expenditure over a few days.

Physiologically there isn't such a thing as an exact ('magic') target weight. 'Set point' weight applies to a weight range in which the body functions optimally. The size of this weight range varies from one person to another. When at 'set point' the person doesn't usually feel too full or too hungry because the body is obtaining the amount of energy it requires and has sufficient energy stores.

Most adults have a 'set point' that lies between BMI 20-25, but this may be more or less in some people and tends to vary with race.
And, of course, some athletes, with a high muscle mass may have a BMI over 30 yet still be very lean.

In conclusion: the 'correct' weight (range) is that in which the individual's physiology is normal and optimal. The reason why there has been research on reproductive ultrasonography is that the female reproductive system usually only 'works' when the body's energy levels are sufficient to sustain both life and reproductive capacity.

Anonymous said...

Carrie, this technique was first reported by Dr J Treasure in 1988.
KCL have studied it through the years.
I hear reports that is used in Britain and has been for some long time.
A PubMed search turned up 11 abstracts, though not all were relevant.
I'll watch for more from you on this.

EvilGenius said...

as a 21 yr old who has never been pregnant and has had periods at a bmi of 13 without taking any kind of contraceptive, this concerns me! it also irritates me that doctors so often dismiss cases like mine as 'rare' as though it doesn't matter or make a difference. it certainly makes a difference to my recovery if methods like this tell me I should be weight restored at bmi 14 or 15 etc!

A:) said...

This confuses me. . .

The weight/menstration thing is confusing in itself. Like many other posters, the FIRST time I got sick I lost my period at an appropriate BMI (like 18) and it returned at a BMI of 20 -- OK. . . normal.

The SECOND and THIRD (being now) anorexic episodes I found myself at BMIs of 16 and 14.5 respectively with a period. Throughout my weight restoration, these periods have continued on a 5-6 week basis, though they are very light (like two days).

In contrast, I knew individuals in treatment programs who had been weight restored for months and still had no period. . .

Personally, I agree with the way the program I attended chose to weight restore individuals. They were brought to a BMI of 20 and then slowly decreased to a predetermined maintenance level with no weight loss allowed -- if they continued to gain, it was "OK" up to a certain point because 20 was not the final BMI but the low end of normal.

One ED psychiatrist told me that it was impossible to determine a person's true weight range because i) it could fluctate up to 20lbs and ii) it would take at least 2 years after restoration for the body to completley normalize and find a set point.

Just some thoughts. . .


A:) said...

This confuses me. . .

The weight/menstration thing is confusing in itself. Like many other posters, the FIRST time I got sick I lost my period at an appropriate BMI (like 18) and it returned at a BMI of 20 -- OK. . . normal.

The SECOND and THIRD (being now) anorexic episodes I found myself at BMIs of 16 and 14.5 respectively with a period. Throughout my weight restoration, these periods have continued on a 5-6 week basis, though they are very light (like two days).

In contrast, I knew individuals in treatment programs who had been weight restored for months and still had no period. . .

Personally, I agree with the way the program I attended chose to weight restore individuals. They were brought to a BMI of 20 and then slowly decreased to a predetermined maintenance level with no weight loss allowed -- if they continued to gain, it was "OK" up to a certain point because 20 was not the final BMI but the low end of normal.

One ED psychiatrist told me that it was impossible to determine a person's true weight range because i) it could fluctate up to 20lbs and ii) it would take at least 2 years after restoration for the body to completley normalize and find a set point.

Just some thoughts. . .


EvilGenius said...

ooh one thing I forgot to add! not a dig at you, cause I know you didn't intend this (and nor does anyone else for that matter!) but these studies which seem to state as scientific fact that menstruation = healthy body are absolute fuel on the fire for your eating disorder if you're someone like me. obviously me sitting in front of a doctor and saying 'oh can I maintain then, I must be healthy' will yield no odds cause I've had very dangerous complications which prove that I'm not healthy. however they also prove that this assumption at least doesn't fit for everyone.

Izzie said...

Although this method sounds promising it worries me. Like others posting here, I was getting proper periods at BMI's of 13. During one of my hospitalizations 6 years ago (I was 16) I had a pelvic ultrasound to determine if my target weight of 100lbs (at 5'4) was appropriate for me. I was told my reproductive organs were maturing appropriately and I could stay at that weight. This was a BMI of 17.2 which is way too low and I was certainly not recovered - physically or mentally.

I do believe a lot of places set target weights way off the mark, I've been recovered for 1.5 years at 5'5 and 120lbs and am happy and healthy, but my last treatment center wanted me at 112lbs and the one before that discharged me at 102lbs.

Carrie Arnold said...


What the pelvic ultrasounds do is take pictures of your reproductive organs and get measures of size and other characteristics. As you go through puberty (and ED recovery), these measurements and features change, so they can compare the ultrasound pictures with other measurements like weight and height to determine whether your body is at a good weight for you.

The pelvic ultrasounds, as far as I can tell, don't measure menstruation per se. I'm thinking that they are used in adolescents to measure relative age maturity of the ovaries because ED generally halts that in its tracks.

I agree COMPLETELY that basing target weights solely on menstruation is both misguided and stupid. Because I've been at a significantly lower weight during a relapse than when I stopped having my period the first time around and still had my period, so menstruation doesn't equal health status.

This is just my own personal appraisal, but in general, women who have been sicker longer will often maintain or resume menstruation at a much lower weight than younger women who haven't been sick as long for two reasons: it takes less trauma in younger females to disrupt the menstrual cycle, and the body does also begin to adapt to the starvation state.

Thank you all for your feedback.

Cathy (UK) said...

I agree with 'EvilGenius' that it can be really confusing to hear doctors say that normal menstruation equates to 'healthy' weight when weight is clearly too low to support normal bodily function. The information I summarised above is what 'normally' happens, based upon research in the field over the past 30 yrs, including my own.

However, there isn't such a thing as 'normal' in Physiology, because research findings are based upon statistics and probability. Everyone is an individual, somewhat unique person!

I would highlight what I said above: "In conclusion: the 'correct' weight (range) is that in which the individual's physiology (i.e. bodily function) is normal and optimal".

Although this has not been researched in any detail, I do wonder whether regular binge/purge behaviours can trick the brain into registering that enough energy is available in the body to promote normal reproductive functioning. The brain is especially responsive to glucose availability and leptin levels. Bingeing on high carbohydrate foods can cause blood glucose levels to rise very high for a short period of time, which in turn leads to the body to release a lot of insulin. Leptin levels closely correlate with insulin levels. Conversely, regular exercise also influences energy levels and the way that the brain (hypothalamus) registers the body's energy availability for reproduction, and individuals with high levels of exercise and restricting AN very, very rarely menstruate.

I could write an essay on this because there's a HUGE literature on this, but (1) I would probably bore people - and (2) This is Carrie's blog; not mine.

I will conclude by agreeing that despite the research evidence for reproductive functioning usually equating to 'healthy' weight, the link may be quite tenuous. What is important is whether the body as a whole is functioning normally and the best it can do. This will rarely equate to a BMI < 19.

Katie said...

Completely forgot about this when I commented last night, but one of my good friends fell pregnant at a BMI of 14.5. She carried the baby to full term, although throughout the first six months of her pregnancy her BMI was only around 16 and her health suffered a lot. Also, when I was in treatment in 2008 my therapist asked me about partners/birth control because two of their day patients had become pregnant at BMIs of 15-16 the previous year despite apparent amenorrhea.

I'm not sure it's as uncommon as people think.

YeracXam said...

Do you happen to know of any studies into target weights and reproductive functions on Male anorexics?

Embarrassing, but I haven't been able to ejaculate for 3-4 years now and struggle to maintain an erection (sorry, possibly inappropriate!).

I've mentioned it to my GP who's only cited the fact that females lose their periods at unhealthy weights and that it's "probably" the "same thing" and if it doesn't come back when I reach a healthy weight then he can investigate further.

Problem is, while I'm a young male and my fertility should be of great importance to me, I also face an eating disorder which my mind insists on prioritising above all else. I also have no idea what a healthy weight would be where I could expect normal functionality to resume. I know it's probably higher than where I am now, but if I wait until I'm "healthy" for my GP to perform tests then, without wanting to be defeatist, it could be a while and end up too late.

I haven't been able to find much online, other than this article ( which scared me with the line "the disease damages the system beyond the point of ED treatment. Once the system is damaged, recovery is difficult. Hence the importance of catching the disease at its starting stage."

I guess I just wondered if you'd ever come across anything a bit more conclusive; Great blog, by the way! x

ex ana said...

I am following this very interesting discussion in two perspectives: the scientific one started with the article cited and commented by Carrie Arnold (thanks! Some articles you find are real pearls!) and the other perspective the comments and testimonies, where the issue of menstrual cycle is frequently referred. I must stress that I have no clinical expertise or even knowledge, but I like to be informed about a disease which nearly killed me many years ago. I am now full recovered, I can say that because more than twenty years I left it [yes, I am an old lady], I prefer to say I ‘forgot anorexia’ ( in Portuguese: forgot=esqueci) My anorexia nervosa was far from being ‘typical’ in fact I strongly believe that this ED has many different and confounding specificities.More than other mental patologies. My personal experience was: I lost my period at a certain point of my AN, not at the beginning (at that time I was around 15-16 BMI ) and I recovered my menstrual period fully and completly, some years after when I attained a normal weight. So, in my mind, menstrual cycle recover and AN end are strongly associated. I was mother many years after and more than once. However, I know about some persons who were not able to be mothers (in the reproductive meaning) having AN occurrences during heir adolescence.
The review article below (available on line) seems to converge with the main opinions presented and testimonies. It argues about the shortcomings of ‘critical weight hypothesis’. The authors defend the “hypotheses based on normal maturational processes, especially of the central nervous system”. So, if this is true the transabdominal pelvic ultrasound scanning ability to determine reproductive maturity is an advance but the maturation of the central nervous system must be studied together. Apologise my long post.
Scott, Eugenie C. and Johnston, Francis E. (1982), Critical fat, menarche, and the maintenance of menstrual cycles: A critical review , Journal of Adolescent Health Care, Volume 2, Issue 4, June, Pages 249-260
Scott and Johnston (1982) disagree with the the critical weight (fat) hypothesis [it “postulates that menarche is triggered by the attainment of a critical percentage fat and that the maintenance of menstrual cycles requires the persistence of a minimal level; each level is argued to be universal for a particular population or race and, by implication, for the species as a whole”]. From the abstract: “the evidence reveals the hypothesis to have a number of serious methodological and empirical shortcomings which may be grouped under three headings. 1st, there are no acceptable measures of body fatness […] 2nd critical levels do not apply.[…] 3rd other confounding factors are plausible. “Consequently, based on available evidence, the critical weight (fat) hypothesis cannot be accepted. Hypotheses based on normal maturational processes, especially of the central nervous system, currently provide better explanations.”

Cammy said...

I wonder whether it matters if someone became anorexic prior to puberty, and has subsequently never menstruated?

EvilGenius said...

must say I am hugely intrigued by Carrie's ideas about the link between binge/purge behaviours and menstruation at low weights. I did indeed lose my period at higher weights when I was restrictive, and now experience a lot of physical symptoms (blood sugar crashes and so on) which suggest that binge/purge behaviour releases insulin and causes general haywire in the body even if minimal calories are absorbed. am definitely going to research this now as I think understanding the causes and effects of binge/purging at low weights are very important to my recovery. and it would make some kind of sense if it impacted on reproductive function.

Cathy (UK) said...

I feel I am commenting too much on this particular subject, but it does seemed to have aparked interest, and, well... I did quite a lot of post-doc work in this area.

EvilGenius asked about binge-purge behaviours. Some of my research focused on the relationship between energy balance, body weight, body composition, hormone levels and bone metabolism. Interestingly, I observed that some individuals with b/p behaviours had higher than expected bone formation, higher insulin and leptin levels, and were menstruating regularly despite low weight.

Cammy asked about developing AN before periods start. I actually did. I was 11 when I started to restrict food and 12 yrs old when diagnosed with AN (in 1977). I didn't have periods at all, for many, many yrs and had a very low weight. I gained over 30 pounds when I was 40 (with therapy) and low-and-behold my ovaries started to function. I was 'gobsmacked'.

YeracZam asked about AN and reproductive function in boys/men. It's not something I researched but it's clearly important. Men are often forgotten as far as EDs are concerned. There's a web site 'Men get eating disorders too'. This might be a place where you could link with other males suffering similar problems. I'll look up the web site...

Cathy (UK) said...


Amber Rochelle said...

Don't really know what to say about the whole test / menstration thing. But I really liked the first part of this post, where you talked about many professionals setting target weights too low, in an effort not to scare off patients. Although having a high target weight would and has terrified me, I almost think it's been more destructive for me to be given a low target weight, and then freak out and feel like a complete failure because my body actually wants to be above that 90% mark. I agree that it's a good place to start. But to say you're cured at 90% is kinda crazy to me. Well, I guess depending on your body type. For my body type it would be crazy. Granted, I'd love to be able to maintain at 90%, but what I want and what my body wants if it's going to be healthy are two TOTALLY different animals.

Telstaar said...

Soo many comments that I am almost loathe to leave my own (and trust me this is the third time I've considered it)...

I guess I very randomly fall into the category of "odd" not only do I very consistently get my periods at a very low BMI (which I have been down around for about 2 years)... but I actually get my period MORE often (every 21 days instead of the prior 28/32 day cycle) and it still goes for the same length. I am the odd one out, I really am.

I know in my case that I could very easily get pregnant, I have a family history that demonstrates falling pregnant easily (ie while taking the pill) and also I know that i get leading follicles every month still (I am an ultrasound model, so I get practiced on quite a bit). I know that all my organs are healthy and of sizes to be expected, I know that the sonographer teaching the doctors can accurately predict where I am at in the cycle still! For all intents and purposes I'm rather normal... but clearly that doesn't mean my weight is healthy.

HOWEVER, my entire life I have not eaten what I should in a day and I do believe my body has adapted to that. I also believe that I have maternal history of extreme fertility and that will add to when I get/lose my period etc. (THe only time I've lost my period was at my HIGHEST weight!)

BUT... I think that essentially without having a calculator to put everyone's details into and come up with an IBW for each person, I think utilising non-invasive technology such as the transabdominal ultrasound, WITH indicators such as general health and menstruation WITH information that we do have such as BMI... then surely we're going to slowly be getting closer to getting a more accurate picture for the majority of people with eating disorders... even though there are odd bods like myself out there.

I would have a major issue (as I already do) with such techniques being used for diagnosis and even as a full picture of clinical severity...but I think as trying to come up with a mechanism for more accurately figuring out where people should be... its a great start :)

That is my, three or four or ten cents worth!


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I'm a science writer, a jewelry design artist, a bookworm, a complete geek, and mom to a wonderful kitty. I am also recovering from a decade-plus battle with anorexia nervosa. I believe that complete recovery is possible, and that the first step along that path is full nutrition.

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nour·ish: (v); to sustain with food or nutriment; supply with what is necessary for life, health, and growth; to cherish, foster, keep alive; to strengthen, build up, or promote


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