Is it possible to be skinny but eat normally?

Is it possible to be very very skinny, but eat normal as every other normal person? Is that possible? And if it is, how do you fix it? How do you gain weight, when you eat normal???
P.S This is not about me! Im asking for my friend, cause she eats...

normal and still is very skinny
Please help me! I really want to help her cause this is her biggiest problem, and I am her boyfriend...???

you cant really do anything, she just has a fast matablism. which means the energy is used pretty quick and this includes the fat. dont worry I know someone who has the same thing.

yeah its normal
it means you have a fast metabolism
this is really hard to change, they just have to be happy they're skinny rather than fat
I know a lot of people like this, you can't really change it, but once they get older their metabolism will slow down and they'll become a normal weight

Unfortunately there's no quick fix to this problem, eating more will not help. She could work out and gain muscle...

MAYBE SHE HAS ANOTHER PROBLEM...DID YOU KNOW IF YOURE SAD OR WHIT STRESS IT CAN MAKE YOU HAVE A BAD HEALTH??? GOOD LUCK FOR YOU AND YOUR G/F!!! KAREN.