I use to be very very skinny. I hated it. would go on get fat diets. where I would fill up on icecream , and eat late at night on purpose. I was serioulsy underweight for my height and age. I thinhk I just had a high metabolism. I couldn't help the way I was. and people use to make fun of me all the time for it. saying I look sickly.
My point is that some people are just naturally skinny, have high metabollism.
As I got older though I started gaining weight.oh how I wish I was skinny again. not as skinny as I was before but at least 10lbs lighter than I am now.