Dieting "behind closed doors" is absolutely not the way to stay on track. If you really want to stay accountable, get vocal. I told my friends via a blog at work that I wanted to lose 100 pounds and let them know I had joined the company's version of the Biggest Loser. Then, I blogged and talked to everyone I know. I really thought only my friends would read my blog, but more than 20K people read my blog and more than 300 people sent email messages or commented. Scary, but keeps you on track.