Cheat Day

I'm feeling quite full and satisfied at the moment.  It's cheat day, and I've started it off with a late-morning breakfast and dessert.  I could go into vivid detail about my dining experience (including what I plan to eat later), but I'll abstain.  It may not be your cheat day, after all, and there's no need to make you fall off the wagon.

I'm a big fan of this strategy for long-term, sustained fat loss. Strategic cheating on your diet does more than help keep you sane compliant.  There seems to be some hormonal advantages to it as well.

Leptin

Leptin comes to mind here. 

We know that leptin is one of the hormones responsible for regulating hunger and body fat.  This hormone sends signals to your brain, telling you that you are full.  It also causes your body to burn/release fat stores.

But leptin levels decrease when calories are lower.  We know, for example, that leptin levels tend to decrease after around 24 hours of fasting--this is one reason the Eat Stop Eat program only requires a 24-hour fast.  Levels are also lower after prolonged low-calorie diets.  This seems to be part of the body's way of holding on to its precious fat stores.

Cheating for a day can bring leptin levels back up and prevent you from having a plateau in weight loss/fat loss.

You may be concerned about ruining a week of hard work in one day.  Based on my experience, it just doesn't work this way.  There's a limit to the amount of body fat you can store within one day, and I've found that any weight gained on cheat day tends to be water or glycogen (energy stored within the muscle).  In other words, the benefits far outweigh the risks (pun intended). 

But I want to caution you about something--this only works if you are compliant with your diet the rest of the time.  You should be on a calorie deficit on every other day if fat loss/weight loss is your goal.