why is it bad to be under 18.5BMI?

Hi,  so I dropped two more lbs and i am tech. underweight right now, but i think it looks good, everyone else say so too, they say no more but that this looks good,  i still have boobs and a but and fat on my tummy and thighs. I am 5 ft 6 and 113.  so what i want to know is what is bad about being under 18.5,  I will say that i know  i have disordered eating and have an anxiety disorder and its related to food. but i am not anorexic nor bulimic...just obsesive and i like healthy foods.  but what i so bad,  should i expect something awful,  i still get my period and that stuff, hey who knows maybe its just today and tomorrow i will gain them back,  but still curious?

As long as your body functions properly I doubt it's a bad thing.

Obviously the anxiety and disordered eating is a problem, and if being at such a low BMI causes you to obsess even more about it, then I would say being at such a low BMI is a problem. 

Well, other people may disagree with me here, but, if there isn't anyone screaming at you to put on weight (in real life), and you're only a couple lbs under, its probably not bad. BMI is a good estimate for weight for most people. Most, but not all. I would advise you to go get a body fat test done, to be sure you still have enough body fat, but other than that, just don't lose any more.

Underweight can also mean undernourished.  Your BMI is at the high end of the underweight category, so it's not that bad.  But if you are contemplating losing more weight, you might want to think about long range consequences.

Long term undernourishment can cause irreversible damage to the bones, heart,  and even the brain.  I'm not saying you are suffering from this, just that we all need to be aware. 

We all know what kind of health problems are caused by obesity, but what we often overlook is, those problems are reversible.  The ones caused by poor nutrition are not. 

"Underweight can also mean undernourished."

Many obese people in the world who live off junk food are also undernourished.

Technically, isn't it possible to be underweight and well nourished?

It's very unlikely. For most people, to get underweight, they severely cut calories. In general, severely cutting calories leads to malnutrition because you aren't getting enough of the right micronutrients in your blood.

Remember, to MAINTAIN at a BMI of 18.5 or less, you need to eat less calories than people at BMI of 22.

I'd even challenge you, anyone of you, to come up with a diet that will give you the calories you need to maintain at a BMI under 18.5, and also give you the nutrition you need.

EDIT: Keep in mind that you get SOME nutrition from multivitamins and nutrition-packed snacks like Luna Bars, but unless you're getting enough fat in your diet, you aren't getting all of it, by far. You need fat in your diet to process the hydrophobic nutrients: A, D, E and K. Otherwise, you may be taking them in, but still not able to process and still suffer from malnutrition.

As I said, sunkissed, we are all aware of the health problems caused by obesity.  Undernourishment is unlikely though, due to the large quantity of food consumed.  Large amounts of even junk food contain essential vitamins. The cheese in multiple cheeseburgers, for instance, can supply the RDA of calcium, but only along with enough saturated fat to block the arteries.

The deadly problems are coronary artery disease caused by consuming too much saturated fat, and diabetes caused by a high sugar diet. Both are exacerbated by not enough activity, which is made difficult because of sheer bulk. Less deadly problems of joint pain, back pain, and difficulty caring for oneself.

All these things are reversable over time with a consistant good diet. 

By contrast, in people who are starving, the brittle bones, rotted teeth, heart problems, kidney & liver failure, reproductive failure, and brain damage are not reversable. 

But please realize that one would have to starve for quite a while for these things to occur.  Just being a little underweight isn't going to do it. 

I was watching a programme the other day about a woman who tripped over and broke her back. The doctors were superised that a healthy 30 year old woman would break her back just by a simple fall. When they xrayed her she had ostephorsis.

She had started 'healthy eating' a few years before hand in order to lose a little weight and it had lead to her just eating fruit and veg, with very little meat, fish, dairy or carbs. It seems that 90% of your calcium is stored in your bones but you need calcium in your blood. When you arent eating enough calcium to keep the levels in you blood correct it takes it out the stores in your bones. Do this for long enough and you end up with holey bones lacking in calcium.

Osetopharsis is just one problem, but theres many many more your could get from under norishment, such as heart, kidney and liver failure!

Surely to go up to 19 BMI wont make you look bad? How about gaining a few lbs of muscle, just increase your protien.

Think it may be worth you posting what you eat daily

I fail to see your point.

I understand that "underweight" is a touchy issue. However, it's easy to become very thin without drastic calorie reduction. A daily deficit of 500-1000 calories can be used to reach any goal.

Furthermore, it is possible for anyone to be healthy at a BMI of 18.5 or lower. A smaller body burns less calories in the run of a day. Thus, calorie needs change. Nutrient requirements also change because they are proportionate to total intake.

If you are an athlete its ok to have a lower than average BMI - you will have less body fat - however, if you are not an athlete, lower BMI (below 19%) actually may lower your immunity.   Tests and studies done on longevity actually show that people with BMI's between 20 - 22 live the longest and are at optimum health.  

Original Post by tandosnip: Tests and studies done on longevity actually show that people with BMI's between 20 - 22 live the longest and are at optimum health.

 Life insurance companies, which bet real money on the lifespan of a given individual, evidently agree. My wife is the picture of health at 5'4" and 115lbs. (BMI 19.7) but when I bought life insurance for each of us, I put down 105lbs. (BMI 18.0) by accident. They raised her premium and she had to get a doctor's certification that she actually weighed more before they would give her the lower premium.

Original Post by hilary_88:

I fail to see your point.

I understand that "underweight" is a touchy issue. However, it's easy to become very thin without drastic calorie reduction. A daily deficit of 500-1000 calories can be used to reach any goal.

Furthermore, it is possible for anyone to be healthy at a BMI of 18.5 or lower. A smaller body burns less calories in the run of a day. Thus, calorie needs change. Nutrient requirements also change because they are proportionate to total intake.

I don't believe that either of these two comments are true.

These comments suggest that you see the body as a simple system.. you put energy in, keep a reasonable deficit, and lose weight. It doesn't work like that.

Your body is not a simple system. It decide for itself precisely how much it thinks you should weigh and as you get closer and closer to that weight, you lose slower. I've got more than a few corroborations on that fact, that the closer to maintenance you get, the slower you lose. And eventually stops.

And, no, not all nutrient requirements change as your body mass changes. Again, it doesn't work like that.

Original Post by hkellick: Your body is not a simple system. It decide for itself precisely how much it thinks you should weigh and as you get closer and closer to that weight, you lose slower. I've got more than a few corroborations on that fact, that the closer to maintenance you get, the slower you lose. And eventually stops.

I can attest to that. I started at 216 pounds with a goal of 180. I've been stalled at 181-182 for a month or more despite consuming a reasonable amount of calories consisting of more fruits and vegetables than I thought possible. I am running 5k daily now and with some weightlifting thrown in a few times a week. No one thinks I look overweight anymore, I just wanted to get to 180, maybe even 175.

I'm beginning to think this is the right weight, even though my BMI is 25.3. If it goes lower it goes lower, but there's no sense starving myself to force it I guess. This may be as low as I get.

I fluctuate between 140 and 148 lbs and am 5'11''. It's shocking to learn that I can't lose more weight.

However, I checked online and it is healthiest to maintain.

Original Post by hilary_88: I fluctuate between 140 and 148 lbs and am 5'11''. It's shocking to learn that I can't lose more weight.

Why are you shocked? Because of what your shorter friends weigh? Runway models? :-)

 You're female and 5'11". I don't even need to calculate the BMI to know that sounds perfect.

Original Post by southcarolinaguy:

You're female and 5'11". I don't even need to calculate the BMI to know that sounds perfect.

20.4 (I DID Have to calculate the BMI :) ). And I agree, definitely a good healthy weight. :)

My weight loss did not slow down at all as I got lighter, it even seemed to speed up. The hardest pounds for me to lose were the first 10, not the 2nd 10. Anyway, yes, I agree, very complex system, everyone is different although there are similarities. Not sure about your age, OP, but that has a lot to do with these BMI figures and what is considered underweight. Because I'm old I'm supposed to weigh more! People under 18 are given a more generous "acceptable" BMI level.

Listen to what your peers and family say. I guess if you read many of the posts on cc from those recovering from EDs you'll know what some of the warning signs are. Take care...

wow so you sound exactly like me! haha i was thinking for a second, when did i write this post?? i too have "disordered eating", am 5'6'' and weigh just under 112 lbs haha.. i definitely don't think we are at an unhealthy weight since we are pretty close to the border between underweight and normal weight.. also bmi isn't 100% accurate as it doesn't account for the fact that muscle weighs more than fat and the fact that people have different frame sizes.. but i think what we are at risk for is.. well, an eating disorder. i wrote a post on this site a little while ago about that and that was basically what i was told.. some said that i was ED-NOS (eating disorder not otherwise specified) and others said pretty much that i was really at risk and needed to try and get better before it got worse. people have started making comments to me about what i eat and my weight which is concerning but i think for our height/weight we are not at risk for health problems. i have noticed that my boobs and butt have gotten a little smaller, i dk if you have noticed that too.. i really want to be 110 lbs and then i am going to just try to maintain that weight because i don't want to lose my boobs and everything that makes me feminine! i think in evaluating whether or not you are at seriuos risk for a disorder you should reflect on how much time you spend each day thinking about food.. and what your deeper probelms are that you take out on your body. i don't know if by being "obsessive" about foods like you say, you mean you make sure to only eat healthy foods, or you literally add up your calorie content for the day.. i would strongly urge you not to count calories, and instead just make sure youre eating low-fat, nutritious foods that make you feel good about yourself.. in the past few days i've really tried to refrain from counting my calories and its kinda hard but its a bit of a relief at the same time not to be wasting so much time thinking about that. message me if you want to talk ab it more cause i can really relate to your post

I'd even challenge you, anyone of you, to come up with a diet that will give you the calories you need to maintain at a BMI under 18.5, and also give you the nutrition you need.

Couldn't you eat like 2000 calories, get all the nutrients and vitamins you need, and exercise? Sure you'd be tired and all, but I think it's possible.  

Actually im 5'8 and 115...im underweight but healthy..and i eat my 1900 calories a day BUT

im trying to gain weight right now on 2300 calories

i also exercise 5-6 times a week

so theres your answer. its possible to be healthy and maintain a bmi lower then 18.5