I'd be wary of any fad diets like vegan/vegetarian, which appear to be based more on ideas than on the reality of the human body and how it functions.
First of all, I think people should eat whatever they like. I would never tell anyone what they should eat. I have no idea what's best for anyone else. I can barely figure out what suits me!
But I don't think it's correct to call a vegetarian diet a "fad" diet. The tradition of eating a vegetarian diet goes back thousands of years in India. I think it was mentioned in the vedas.
My husband is 61 and he's a lifelong vegetarian. His family has a vegetarian tradition going back for many generations. (not vegan -- the vegetarian tradition in India usually includes lots of dairy and no eggs, but there may be exceptions that I don't know about)
You may not agree with with eating vegetarian foods. And I have no desire to convert anyone. But if a vegetarian diet is a "fad" then it must be the very longest fad in history!
Actually, the "fad" in India seems to be the new fast food places like KFC and Subway. They didn't exist 20 years ago. All the kids love them--so much more fun and hip than the "old fashioned" vegetarian food that they would get at home. It's just funny to me that in Western countries it is vegetarian food that is seen as a fad.
PS for Sasha - Sorry that my post went off on a tangent--I didn't mean to hijack your thread! I would definitely advise listening to your body so you can try to find out what foods suit you. I would say talk with a doctor but, yeah, right, that's probably a waste of time. Very few doctors seem to know anything about food or nutrition, sadly. Maybe you could find a nutritionist or naturopath or something?
What's important is to find a diet that suits you. What works well for one person might be horrible for another since we can all have different allergies, food intolerances, and so on. Good luck!