Despite the name, like most twelve-step programs Overeaters Anonymous actually deals with both ends of the food spectrum - with any kind of dysfunctional relationship to food and eating, whether it's anorexia or bulimia or compulsive overeating or something else entirely. It's a free (but they pass the hat for totally voluntary donations), peer-led, supportive environment where people come share about their problems with food and the tools that have helped them. And along the way, people learn tools for a healthy life.
The OA East Bay website, http://www.oaeastbay.org/, has information about local meetings and about deciding whether OA would be useful to you. Every meeting is different; try several to see what kind you like.