My son has been using enteral nutrition for almost three years now as a main treatment for his CD and main sores of nutrition. First formula that put him into remission was Modulen. Unfortunately it's not available in the US anymore. My son prefers this formula over the Peptamen and Nutren. The only side effects from the formula my son experienced in the first several month was loose stool and urgency to go to the bathroom (which are not his CD symptoms).
It's very important to use Modulen drinks exclusively. You can have some diluted clear juices (my son drinks just organic apple juice), some people have clear lolly pops but I never gave them to my son.
For my son it takes from 8 to 16 weeks to achieve remission. Reintroduction of foods never lasted long for him unfortunately. We tried very very carefully with one food every 10-14 days approach but when something does not agree with him he has flares and taking this particular food from his diet does nothing so every time he needs to start over with the exclusive liquid diet. This time he is not eating since last September (with a tiny Thanksgiving exception that caused him a bad flare).
If you'd like you can order a book from amazon.com that's called IBD Remission Diet by Jinny Patel Thompson. It contains nice summery of foods from less to most aggravating.
Sorry for my English and good luck.
Chachka (almost 13 y.o. son with CD, exclusive enteral nutrition, LDN cream, Digestinol)