Why is that ugly little kids turn out to be handsome when adults?

You have experienced first hand the dramatic changes that puberty can cause on your body. Your growth spurt and accompanying change in metabolism kept your body weight almost the same while you increased in height 8 inches. There are changes to your basic bone structure when going through puberty. This also takes place in your facial structure. How you look is what makes the initial impression on people. It gives you the opportunity to form an acquaintance with someone, whereas if you were this fat kid, or plain looking kid, or not so good looking, you may not be approached. Only after someone gets to know you better may you form a friendship with them. That initial impression your good looks provides for you will only last a few minutes if you have a personality problem. Once a person gets past the good looks they want to know the person behind the face. You may look like a male model, but if your personality sucks all the advantage your good looks provide will disappear. I am glad you are not that "fat and ugly" kid you once were. Just make sure you do not place too much importance on good looks now. Do your best to develop a pleasant personality that matches your looks.