I've been contemplating something, and I only have a personal anecdote to go by, but I think the importance of sleep is being vastly underestimated when it comes to weight loss.
Late last year I had a pretty big shake up in my life, and without going into too many details, I spent a little over a week basically just sleeping. Afterwards I had morning classes and evening training to keep me on a schedule with about 5 hours in between. During this time I didn't have a smart phone and only used my computer to watch TV (no games), so I slept when I was tired and woke when I wasn't. At first I fell asleep as early as 9 but usually around 10, waking at 8 (without an alarm clock) and frequently but not always taking afternoon naps. Eventually my fall asleep time crept up to about 11 where it stabilized.
After about 2 months of this I never felt better in as long as I can remember and the weight just melted off me at a shocking rate, about 2 kg a week, to a point I would consider it a little unhealthy. While I did eat better and train more, these were all things I have done before (with slower success), the drastic increase in sleep was the new element.
I, unfortunately, don't have the same schedule anymore and while things are going fine I don't sleep nearly as much or as well as I was and I can feel it in the morning.
Could we be underestimating the role sleep plays in all of this? While stuffing your face with potato chips and hohos while awake and sleeping the rest of the time obviously won't cause weight loss I find myself wondering where working on your sleep becomes more important than training more or eating less. Could that point be sooner than we thought? Could paying back your sleep debt and not accruing more play a much larger role in a healthy life than we've given it credit for?