Well, there's always the Master cleanse that's been around for about 60 years.
Just google master cleanse or "lemon cayenne maple syrup cleanse" and you'll find many, many websites describing it. I haven't done it, but know people who've done it for health reasons or (more commonly) to diet down fast for an event (mostly HS reunions).
The only thing you really have to buy that's pricey is maple syrup. I think it calls for freshly squeezed lemons, but the folks I've known who've done it have used bottled juice.
Not my cuppa, but each to his own. Who knows, I'm vain enough about my photopass photos that I may try it right before I go to WDW this fall.