Personally I like to have some downtime on the weekends. Unfortunately for long term weight loss that doesn't seem like a good choice, though. And it's probably why my weight hasn't budged since mid December!
I read an article about a month ago about a study where they analysed the habits of people who lost weight and kept it off for at least one year. One of those habits was that they held themselves accountable every day. No weekends off. They would allow themselves treats, but only within the parameters of their weight loss plan.
I couldn't find the original article, but here's one that looks at the same study and says the same thing:
I guess the key is following a diet plan that is kind enough so that you're willing to follow it every day of your life.