I am thin

During my break in December, I got a couple of people who told me that I lost weight. I guess I lost weight when I went up to Mount Murud in July as I was down with food poisoning when I was coming down and could be too that when tracking up (4 hours) and tracking down (8 hours) I lost a lot of water and also weight at the same time. It is really easier for me to loose than to put it back. So I really have no idea how I am going to put back what I already lost.