Restrictions beat moderation

Greg makes a valid point, if you go 95%, everything is an exception.

Which is to say that anything less than a full commitment is likely going to fall apart.

The reason moderation is difficult is because humans didn’t evolve for it. Times were tough. Food was scarce. When they consumed, they gorged, because knowing where their next meal was going to come was far less certain.

So it's no surprise that the diets that last are often the result of a complete lifestyle makeover as opposed to those that rely on moderate temperance and perhaps a cheat-day to “reward” oneself.

The same can be said for any behavioral modification program. You go cold turkey, and you avoid the trigger for life. Or you incorporate a new habit into your routine, and you do it everyday—same time, same place—indefinitely.

Whatever the case, the kind of commitment that works long-term is the type that retricts freedom of action moving forward. The less choice, the less options, matched with the obligation not to reconsider your decision to commit in the first place, makes it far easier to stick to the program.