Originally Posted by FlyAway
Thanks all for the suggestions! It may be a blessing but sometime its rather difficult to buy clothes and being thin makes you look sick too. I prefer to be average size rather than on the thin side.
You should look at keeping a food diary, log down what you're eating and work out the calorie content. There's some useful sites out there to help with this (I've used nutracheck before when trying to loose weight).
You'll probably find one of two things either a) you're not eating enough or b) you're eating the wrong types of food at the wrong times. Crazy as it sounds, some people maintain a very low weight because they're undereating in calories, despite consuming silly foods like 10 jam doughnuts or a packet of crisps for breakfast.
One other way to put on weight is swap one meal a week out for a takeaway. A typical Indian or Medium (12") pizza will contain 3000-5000 calories and is often a way to tip the scales