How to "StickK" to Your New Year's Resolutions

I previously blogged the "Commitment Contract" idea (www.StickK.com) from Ian Ayres (Yale Law School) and Barry Nalebuff (Yale School of Management):  You give them an amount of money.  If you attain your goal (e.g., lose weight, quit smoking, exercise more), you get the money back with interest; if you don't, the money goes to charity. For further discussion of the concept, see:

• University of Chicago Law School Faculty Blog (Eric Posner)
• Conglomerate (Gordon Smith)
• Marginal Revolution (Tyler Cowen)
• Yale Economic Review

For the tax consequences of commitment contracts, see the discussion by Sarah Lawsky (George Washington) below the fold:

Tim Harford of Slate has entered into such a contract with Ayres (and two others): he has given them $1000, and for each week that he does not do 200 sit-ups and 200 push-ups, they will send $100 to a charity of his choice (a 501(c)(3), as it happens).  If Harford does the sit-ups and push-ups, he gets the money back (with interest, presumably, though he doesn't say).   Ayres et al. are also starting a company, Stickk, that will offer similar contracts to the general public.

I'm sure there are plenty of interesting non-tax issues related to commitment contracts and Stickk, but I am (of course) more interested in the tax questions this sort of plan raises.  For example:

(1)  How should Stickk treat the money it receives?  As loans?  If so, is this sort of loan best treated as contingent debt?  Or is Stickk acting more like an escrow agent?  Alternately, does Stickk's treatment of the money it receives depend on what the person is committing to do?  If someone commits to lose 50 pounds and keep it off for 5 years, should Stickk treat the money it receives from him as income, given the extremely low likelihood that a person who loses a large amount of weight will succeed in keeping the weight off?  Should it matter if Stickk can present a study that shows that commitment contracts increase the likelihood that the person will keep the weight off?  Should Stickk have to analyze the likelihood of a payout for each type of commitment? 

(2)  How should Harford and others who sign contracts with Stickk treat their payments?  Should Harford get a bad debt deduction if he doesn't get his money back?  Should that depend on what he has committed to do (i.e., how likely he is to succeed and thus to get his money back--in other words, on the level of risk involved)?  What if his payment is not a loan?  Depending on what he commits to do, could he treat it as a payment for health care?  Can he seek reimbursement from, say, his Flexible Spending Account?

(3)  If Harford does not keep the weight off and the money goes to charity, should anyone get a charitable deduction?  Presumably Harford does not want the money to go to the charity; he would prefer to lose the weight.  Does that affect whether a deduction is available?  Harford in fact chose a charity he refers to as "hugely deserving," but what if Harford had chosen a charity he hated, a charity he really did not want to support, in order to increase his incentive to lose weight?  Would that affect the deduction?