Please help with weight gain

[0nyx]

Hello ladies (and gents if you can offer a word of advice) ..

Long story short, my girlfriends younger sister is in desperate need of weight gain. She looks as if she is almost anorexic (sp?) but she is not, she just doesn't seem to put on any weight (I know this for sure because i watch her eat ). She does not work out do any sort of sporting activities, this is just for her overall health.

I want to put her on a general diet that she can follow, but being young (18) and picky , I am just looking for a basic diet plan that i could try getting her to follow. Any help would be most appreciated!! She has also said she is willing to try protein shakes too as long as they taste alright lol So i am going to order her some protein from Trueprotein (any further suggestions as to what the best type of protein for her would is more than welcome ! )

Thanks for any help offered!