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How does a low BMI relate to anorexia? When is someone just underweight vs. anorexic?

Posted by meganyonak

I am 5'7" and weigh 105 lb.  I am 28 years old and just joined the Air Force Reserves last year.  My husband and I are both in the Air Force and from being away from eachother for almost a year, we have decided to start a family.  I haven't had my period for 4 months and had been on birth control prior to that.  I have lost some weight over the past few years, but I don't feel 'rail' thin or anything.  I went to the doctor this week and she told me that I am probably not getting my period becasue I am way underweight.  I'm on provera for 5 days to see if I get a withdrawl bleed, then do a ovulation test to see if I get the LH surge.  If not, then it's because of my weight.  My doctor told me that I would have to gain a signifigant (in my mind) amount of weight to be 'healthy'.... But I don't know if I believe her... 20 lbs is way too much-  I wouldn't feel good about myself at that weight.  I'm just wondering in my BMI is so low that I'm in an 'anorexic' catagory... It really made me sad to hear that my body doesn't have enough fat to produce the estrogen levels necessary to ovulate.... Maybe my busy life has taken me from a 'grazer' to hardly ever eating at all.... I don't know... Do you have any advice, answers, questions?  Thanks,  Megan
Answers (6)
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The BMI charts don't judge whether or not you have an eating disorder. Nor do I think they take into account the differing body types humans have. They are a "one-size fits all" approach to what is considered an "ideal" weight for people.

That said, you do have a very low BMI. It's 16.3. That is enough to raise concern, just as my very high BMI is enough to raise concern. A "healthy" or "ideal" BMI is considered to be between 20 and 24. At 5'7", you would need to weigh about 129 to hit 20. 

There is no doubt that being too thin can cause ammennorhea, which is the lack of a period. However, going off birth control can also screw with your cycles, so four months might be a bit soon to declare it true ammennorhea. 

I am guessing that being in the Air Force, you probably have lived an extremely athletic lifestyle, which can also result in not getting periods. Many elite athletes don't get periods. If you do exercise a great deal, cutting back on the workouts may help to get your cycles more regulated, too. 

As for whether or not you have an eating disorder, I can't answer that. None of us here can. However, I am somewhat concerned that at the very least, you may have a disordered pattern of eating. 

105 pounds is definitely quite thin for your height. You may be very small boned and naturally petite, which certainly does happen. However, I would consider trying to make eating regular meals a more focused goal, rather than gaining weight. You don't necessarily need to eat copious amounts of food, but consider that when you do get pregnant, you will want to ensure your child is getting all of the necessary nutrients from you. Make eating breakfast, lunch and dinner a priority, and take it from there. It is absolutely essential that you eat enough to fuel your body during pregnancy, and getting your body prepared for that major change is critical. 

If you haven't already started, take a prenatal vitamin daily. Make sure it contains 800 mcg of folic acid, as that is critical to fetal development, and it's good for us anyway. You can make your meals as healthy as you want. Eat whole grains like oatmeal with dried fruit for breakfast. Make it with milk instead of water to gain some protien and dairy. Incorporate nuts into your diet, as they are full of the healthy fats we all want to get more of. 

The bottom line is this... if you find the idea of eating three meals a day scary or worrisome because you may gain weight, then you should find a therapist and talk about a possible eating disorder. If you find the idea time consuming, but you're willing to do it, then you probably have just become overwhelmed with life and haven't been taking care of yourself properly. 

I recommend buying the book "Intuitive Eating." If you truly are anorexic, IE is something that can be challenging early on in recovery, but if you've just become adjusted to eating in a disordered way, this book can really help. 

The bottom line, however, is simple. If you want to get pregnant, you need to eat more. Not because I necessarily am convinced your ovulation issues are related to your weight, but because at such a low weight with such an erratic eating pattern, you would be risking the health of your baby if you could conceive right now.  Furthermore, consider that when pregnant, you should gain about 20 to 25 pounds, especially because you are starting at a very low weight. If that idea is very difficult for you, then I would definitely say it's time to be assessed by a professional to see if there is reason to support an eating disorder. If there is, you want to get that under control before getting pregnant. 

Good luck. I have dealt with infertility, and it is very, very hard. I wish you all the best and hope that by eating more regularly, and perhaps exercising less (if you do exercise an extreme amount currently), you will be able to easily get pregnant and have that beautiful, healthy baby you dream of... 


It is true that biologically, a woman needs an adequate amount of body fat in order to menstruate. Given the weight and height that you mentioned, it is likely that you do not have an adequate amount of body fat to do so. Body fat is essential for good health, contrary to popular belief.

You may not "feel" too thin, but your body may be telling you otherwise. Your doctor will likely know best how to help in this situation.

I did blog on Wellsphere about this...pregnancy and eating two parts. Hope the entries help you.

Dr. Sari Shepphird

Megan, there are two components that go into an eating disorder- the physical and the psychological. Your doctor is telling you about the medical part (even though you don't want what she says to be true :). You also need to look at the psychological/emotional piece. It is for sure possible to be low weight and not have an eating disorder, and it's really important to determine whether that's the case. One way to begin to do that is to ask yourself some questions. For instance, what's your relationship with food (is food a "neutral" thing for you or is it emotionally charged- do you think some foods are good and bad? do you judge yourself as a good or bad person based on what you eat or don't eat)? what's your relationship like with your body (are you comfortable in your body? do you like your body? do you see your body as a "colleague and collaborator" in your life or as an "adversary", something to be "managed" or "kept in line")? how's your relationship with yourself these days (are you perfectionistic, flexible, critical, realistic, gentle/compassionate, harsh with yourself?). Your answers to these kinds of questions will begin to tell you if your low weight is purely a physiological occurrence or if it is linked into your emotions/psyche. It can be a challenge to ask these questions of ourselves, and even more of a challenge to tell ourselves the honest truth about the answers! It's crucial that you do ask them, though, because if there does turn out to be an emotional component involved, you'll need to address that (especially if you want to become pregnant- because pregnancy involves all kinds of changes to our bodies and these can complicate or exacerbate any emotional/psychological issues we may have related to our bodies). Best of luck to you! Johanna

hi, im the same as you:

im 13 years old and im 5'6" and my BMI is 15!

although you may think 20lbs is alot of weight its for your health and if it came from a professional i can assure you what she says is true. although saying this-you have to feel comfortable with your weight to so dont do anything your uncomfortable with.

i mean im anorexic and have an eating disorder. i cant stop losing weight and ive been in hospital and all sorts. 6 months ago i was fine-perfect,healthy...happy! now im a shadow of that person. i mean ive been taken out of school and everything. last week i had payed to go to france with my friends on holiday and the doctors told me 2 days before i was going that i couldnt go on medical terms. im not aloud to move around and its horrible. the doctor said i have to put on 20lbs to just so that i can go to school for 1 lesson a week - i have to put on 2 stone just to be able to see my friends and family! until i put on 2 1/2 stone i cnt go back to school. im 13 and im living in a tragedy!

i started by going on a healthy eating diet where i swapped bad food for good and from then it just went downhill. the reason i dieted was because of the mean spiteful comments people said to me. they called me fat and they poked and pointed at me. so yeah when you laugh at someone who's a little chubby you may mean it as an innocent unhurtful joke but maybe just maybe you might just ruin there life.

im telling you this because anorexia is not a nice thing. its not fun-attractive-it is not a fun thing it is a tragedy! it is like hell on your shoulders all day whispering in your ear.

so yh if your doctor says put on weight - you do it because this isnt just about you any more - this could ruin your future - you may be removed from your job and you may just ruin your chances of a family.

so yh i say use all your will and fight and just live your life like you should.

swap all low calorie content food to full fat!

so stuff what other people say about you - so what if they say nasty stuff-i can assure you they are just jealous and you are probably perfect-i just wish i had took this advice before it hit me. 

i wish you the best of luckxx

my names lizzie and i have anorexia nervosa!

use your life- you dnt have a second chance. 

I'll make this a simple answer, your BMI is 16.4, which is underweight.   according to the BMI charts that I am studying I am on the internet underweight is < 18.5

Being underweight will cause a whole bunch of health problems like the absence of your period and that is only beginning of the hell that anorexia put your body through.

Ask your doctor for help now,please before you drop down to 89! 

I will make this answer simple, you underweight.  Your Bmi is 16.4, under is <18.5, which the absence of your period. I don't your Doctor even believes your are going to start having regular periods without some weight gain even though you are on birth control.

Only time will tell.  Check yourself, are you eating? Are you sleeping? Dizzy spells? Sound familiar? Do something before you get down to 89 pounds lady! 

NOTICE: The information provided on this site is not a substitute for professional medical advice, diagnosis, or treatment. Never delay or disregard seeking professional medical advice from your physician or other qualified health provider because of something you have read on Wellsphere. If you have a medical emergency, call your doctor or 911 immediately.
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