Check out The National Weight Control Registry. This is a data base of succesful weight loss maintenance. Here are a few of the findings:

• Registry members have lost an average of 66 lbs and kept it off for 5.5 years.
• 45% of registry participants lost the weight on their own and the other 55% lost weight with the help of some type of program.
• 94% increased their physical activity, with the most frequently reported form of activity being walking.
• 78% eat breakfast every day.
• 75% weigh them self at least once a week.
• 62% watch less than 10 hours of TV per week.
• 90% exercise, on average, about 1 hour per day.

There is also an online bibliography of peer reviewed publications from the NWCR.