Hi... I'm an 18 years old gal... ma height is 157cm and weight is just 40kg... everyone laughs at me that am looking very lean and I don't have any health.. though am taking food regularly... am not getting fat... wat to do for that? Any ideas..

No one is going to give you advice to get "fat." being fat is not healthy. You can work out and do more weight lifting and make sure you're eating plenty of protein after work out to increase your muscle mass. But some people's metabolisms are just faster than others.