Dave Nunley is a food phobic in the UK who has primarily subsisted on grated cheddar cheese since birth. Although he's eating up to three times the amount of fat recommended for the average diet, he seems to be in fairly good health, save for a vitamin B deficiency.
This isn't as uncommon as you might think. Unlike fad diets that eschew one corner of the food pyramid for another, food phobia is an actual fear-based aversion to a particular kind of vittle, either due to taste, association, or texture. The disorder, which psychologists believe has links to obsessive compulsive disorder, can lead to nutritional deficits, a compromised immune system, and a lot of awkwardness at dinner parties. Orthorexia, a similar condition, is an obsession with healthful eating that can at times become so severe that it leads to anorexia, but food phobics find their meals dominated by their fear. Ironically, legendary egg-shaped director Alfred Hitchcock was an admitted ovophobe, and was "revolted" by eggs.
Update: It seems the Brits have cornered the market on uncovering food phobias. The show Freaky Eaters on BBC Three documents individuals with such severely restricted eating that they avoid certain food groups altogether. The show aims to help each person overcome their aversions and adopt a healthy diet.
(thx jodi)
Update: Another British export is the website Adult Picky Eaters, which aims to provide a forum and self-help information for those struggling with food issues. The author also documents her struggle with picky eating, and the comments on the site are pretty revealing.
(thx rob)