My girlfriend is pretty skinny, but it's not really her fault. She has a condition that makes it hard for her to eat at all. Food with any fat in it tends to slide right through her without digestion unless she takes a literal hand full of digestive enzymes. It still makes her reluctant to eat, and especially overeat despite knowing I am a feeder. Even when she does eat she doesn't actually get as much caloric benefit as she should either. I should also note that she's got some kinks too, most notably, she likes asphyxiation.
So, long story short, medicinal marijuana. We tried it, and found that after using it, she is able to eat without enzymes or any digestive discomfort. For pretty much an entire day afterwords, not just during munchies. It's really incredible results.
Today, we went to an Asian buffet to test the limits. She was wearing a pleated plaid skirt that was really loose except at the waist. By the time she was done eating, the zipper and button on the side were forming a diamond, and when we got back she found she could barely undo the button. When she did, it popped off, and when she tried to put it back on found that she couldn't get the two sides to meet.
We made out pretty hot and heavy after, and she found that, freed of worry about intestinal pain, she really enjoyed the sensation of having a stuffed tummy. Especially when I pressed against it, because it was a pleasant pain and also, for her benefit, made it difficult to breathe.
She just told me "I'm gonna need to exercise more if we're gonna do that again." Which means she wants to do it again. If we make a habit of it, I don't think any amount of exercise will save her wardrobe. Another girl converted!