whats causing my weight gain?!

Could I have PCOS?

I have gained 5 lbs recently with no explanation. I haven't changed my diet at all I'm probably eating less because of the gain.  I haven't changed my level of activity - been going to the gym once or twice a week for the past few months so am actually doing more than before. Its just really weird and dont understand why.

In addition - I skipped a whole period the other month without explanation and this month i 'spotted' but then nothing came and I'm still waiting.

Your weight gain may not be related to your period.  But I would see a doctor about your period right away.  If you are generally healthy and of a normal weight, losing your period could be a sign of pregnancy or of a whole host of gynocological problems.  Or it could mean nothing at all.  Better to be safe than sorry.

Weight gain is usually due to eating too much.  You say "probably eating less", but unless you actually are tracking your intake and know how many calories you are eating, it is a good bet you are eating more than you think you are.

Of course it could be water retention.  Some of us just hold water.  Regular exercise, drinking plenty of fluids and getting a good electrolyte balance all help the body to shed excess water.  You notice I say "electrolyte balance" instead of "limit salt".  That is because restricting salt too much has also proven to make the body retain water.  What you really need is a balance of potassium and salt.  Eating a potassium rich diet and limiting salt from processed foods is more helpful than cutting salt alone.

Well I'm definitely not pregnant I know that for sure!

I wondered whether it was related to me going to the gym as my weight gain has coincided with me starting working out - I don't do a lot of it though, only a couple of times a week running or cross trainer - dont do weights or anything though.

I don't eat many calories at all - probs about 700-800 a day which I kno is not enough so think I have destroyed my metabolism but would this cause a gain of 5lbs all of a sudden over a few months?  Ive been eating this much for years so why does it only happen now?

i also agree that you could be retaining water. keep your sodium intake in check.

that in mind, if you are only consuming 700-800 calories per day, chances are great that your body is reacting to the lack of calories. you are not eating enough, so your body will begin to store any calories you put into it. its biological protection against starvation and could also explain the irregularities in your menstrual cycle. on top of this, if you are working out you are probably burning another 25-50% of those 800 calories each day. 

the minimum calorie intake for a females is approximately 1200 calories(regardless of height and weight). anything less than this creates the risk of damaging your metabolism. from this minimum amount you should raise your intake based on your height, frame, and goals. as counterintuitive as it seems, you need to eat to lose weight. bump up your calories and you should see a loss.

if you are having difficulty calculating your ideal calorie intake, use this CC tool to help: http://caloriecount.about.com/cc/calories-goa l.php

good luck! 

 don't worry about PCOS unless you haven't got your period for 3 -4 months. that is what my OBGYN said. 

just increase your calories and you will be fine. also, if you lift weight, you could see different readings on the scale just from muscle gain not fat gain. 

so why don't you take your measurements and see if you are losing fat or not.

don't worry, you will be fine :)

really? So you mean if I actually start eating more I will LOSE weight?  How does this work? What will happen to me?

As for salt...I dont know whether I eat a lot of it - I never add it to my foods - I eat loads of fruit although I do eat a lot of cereals that probably have salt- do these cause water retention?

When your body is not receiving enough energy from food, your metabolism slows down drastically. At this point, your body is burning calories as slowly as possible in an effort to conserve the energy you do have. The result is you hitting a plateau or sometimes even gaining. Our bodies are intelligent systems and will respond if they anticipate that food will not be available for an extended period of time. 

Once you begin eating an increased amount of calories, it will probably take time for your body to adjust. You probably won't see immediate weight loss. Just keep exercising and eating balanced meals...in time, your metabolism will recover. About 2 lbs a week is the maximum amount you should lose- anything more is risky to your health.

Normally it would be logical that extra weight could be from muscle you are building at the gym, but I'm not so sure you could add muscle like that without proper nutrition. I would rely on measurements over the scale for an accurate understanding of your progress.

Not sure about the cereal you eat -I am sure that certain cereals probably do have a higher sodium content (as do most processed foods). Salt can hide where you least expect it. the only way to know for sure is to read labels. Your max sodium intake will vary based on age, health, etc. I am 25 and try to stay under 2000mg daily, plus I drink a lot of water. Ask your doctor if aren't sure or if you have high blood pressure.

Keep in mind, I'm no MD...I would encourage you to do research on your own to find out more info.