Not exactly an obsession, but a very narrow range of acceptable food here. It gets embarrassing if I have to mix with people because I'm always thinking "I hope they won't try to feed me or make me go to a restaurant," and if I have to feed them I feel scared that what I offer them won't meet their expectations at all. I don't do so badly with vegetarians, vegans and health-conscious eaters, because there's a lot of overlap there with my preferences.
Acceptable: wholemeal bread, olive oil, most salad vegetables, beans, pulses, potatoes, eggs in moderation, spinach, grapes, nuts, a bit of "unprocessed" cheese, raisins, hummus, green peppers, courgettes.
Unacceptable: meat, fish, salt, hard fat, more than a tiny bit of vinegar, moderate amounts of sugar, processed foods, hot spices, refined foods generally, GM food. All food prepared by commercial vendors arouses my suspicion, though I've been known to take the risk. I've had food poisoning at least twice that way, but only once through home-prepared food, and for every meal I've eaten in a cafe or restaurant, or from a takeaway, I must have eaten hundreds that were made at home. My gastro-intestinal tract doesn't give me a lot of trouble and I want to keep it that way.
it's very important to me that I enjoy my food but I don't like spending too much time eating it, preparing it or clearing up the mess, I'd rather be doing more interesting things, so I tend to minimise the whole food thing, and just stick to what works for me. It gets pretty repetitive but I can endure that for a long time before the desire for a change gets the better of me.