Ohh I have Crohn's disease also - my weight gain was due to steroids and sulfasalazinne- I was told on numerous occassions that I would never lose the weight so I never bothered until last October. Have lost about 11.5 kilo's since then. Good for you for helping your friend out. I'm sure you both will do well.
BTW I have had Crohn's for over 40 years! The doctors just named it differently back then. The weight will come off though - regardless what any one sayd. I am still on medication andit is still coming off me, through a lifestyle change - which does not mean I do not have some things that I really enjoy. I go 80/20 and one day a week I will have a chocolate bar or chocolate biscuit/cake/etc.
Acutally over the Christmas break I was very, very norty, norty norty
and still managed to get the weight to go down at a steady pace.