Expert: Ryan Hale - 11/11/2009

Question
QUESTION: Hi,, im 17 and i think im underweight...cause my periods are gone again . I had the same problem 2 years ago...so i had to gain a lot of weight ...so then  i lots a couple of kgs again in the last few months, so  my periods stopped 2 months ago, but i dont think i can be under weight again!?! I'm already weighing a lot more than i use to!! Can it be because the last couple of months i've been on a low carb diet (very low)....?? I really dont want to gain all the weight again...and can i maybe do some kind of exercises that will make me weigh more, without gaining the weight literally, like fat and around hips etc.??
I'll really appreciate it!!

ANSWER: Anna- for some young women, their periods are not regular until their 20s.  However, if you developed a regular cycle and now its irregular, it could certainly be from the low carb diet (or any restrictive diet for that matter).  The body mass index charts are useful and you can find them on different web sites (the one with the food pyramid and BMI that the US government offers is pretty good).  I find it more useful to go by body composition... that is your lean body weight.  That is more difficult to get because you have to use skin calipers, an infrared device or hydrostatic weighing which uses a scale and water tank submersion.  You may be able to get a fitness professional at a local fitness club or center or physician to check your body composition.  

When a woman's diet tells her body that there is a food shortage (either due to starvation or restrictive dieting), her body makes the decision that it would not be good to have a baby just then.  So, the menstruation stops or become irregular because it is trying to stop.  If you want to gain weight without gaining body fat, working out is a great way and especially if it incorporated weight training.  Don't worry about lifting weights, you won't get big and bulky like a guy because you lack the hormones necessary.  You will get stronger and add some muscle rather than fat.  Your cloths will fit better than if the weight you gained was just fat and you'll feel better and more fit.  Any calories you take in that you don't use for energy, you store as fat.  So, if you use the calories you are taking in for exercise you will be less likely to store them.  You can over do it though.  You need to make sure you are taking in enough calories to fuel your exercise.  Once again, a qualified fitness professional can work with you to discuss your calorie needs as they compare to how much energy you are burning for exercise.

I'm not sure what the resources are in your community, but a qualified person at a local recreation center or fitness facility is a good place to start.

---------- FOLLOW-UP ----------

QUESTION: hi ,thanx so much for your response!! i really appreciate it!!
Well i'm about 1.57m and 43kg now....which makes my bmi about 17.4 ...but i see it needs to be at least 18.5. That means that i dont need to gain too much. Well, a year or so ago my weight was 35kg and i also had no periods (i was teribly under weight and they told me i had to start gaining weight) so after a lot of trouble etc i gained all the weight to about 46/45 kg...but i felt so fat so i thought i just have to lose i few, which i did the last 2 months, but now my periods have stopped again!
First of all why does your periods go away?? underweight?? or too little body fat? or both?
And is it posible to be underweight, but still have a lot of body fat? or not to have enough body fat, though your not underweight??
Because i really dont look that thin...and i dont think im a crazy person who just sees fat, but i really looks asif i should still lose a kilo or 2...
Anyway i am working on getting my periods back , i have stopped with my low carb diet( low gi) (well to be honest the last couple of months i almost didnt have any carbs) and have started exercising the last week...cuz i really dont want my parents to know ... I am jogging now...is that okay?? I really love it! cuz i dont really want to go to a gim...but if i have to i will...So  rigt now i will start doing weight training too! should i do it all over ?? arms ,legs and everything?? and is situpps okay??
thanx very much!!! i really appreciate your help!!
anna

Answer
Anna- I'll take your questions one by one.  First, the amount of body fat and your hormone levels work together so that your period is dependant on having enough body fat.  Like I said earlier, it's a survival mechanism from long ago so that a woman wouldn't conceive a child while times were tough and food was scarce.  The crazy thing is that there are some women who will lose a little body fat and lose their menstrual cycle while other women may get very low body fat before they lose theirs.  It is also a regulatory mechanism for body density so if you lose your cycle, you are also effecting your bone density and putting yourself at risk for osteoporosis early in life.

It is possible to be very thin and still have a poor body composition (as far as fat to lean body weight goes).  Take the really thin fashion models, because they have very little muscle, their body fat percentage is sometimes not very good.  Think of it this way, if I weighted 200lbs and had 10% body fat.  That's actually considered normal and pretty good for a guy.  It means that I have 20lbs of fat on my body.  If I gained 10lbs of muscle through training, even though my weight went up, my body fat percentage went down right?  Your BMI is not far from starvation levels for someone who is 5ft 8in (I'm not sure how tall you are).

When it comes to working out, weight lifting will help develop muscle and build bone density.  Running is great for cardiovascular health, but you have to make sure you are adding enough calories to fuel your energy needs and build muscle.  Remember, you won't get huge like a body builder.  The goal is to add calories for your health, add weight training for overall health, bone density, and to add weight without adding just fat stores.  You have to eat more calories than you are currently getting if you add exercise to your daily routine.

As for the weight training, upper body, lower body and abs are all part of a good fitness plan.  You can train upper one day, lower one day and alternate days like that.  You can run every day and do abs every day and make sure you have 1 or 2 days off each week... the key is to eat enough to supply energy to working muscles!!  I can't stress that enough.  Make sure your diet includes a wide variety of foods so you will get the nutrients you need as well.