I'd like to thank everyone for taking the time to post here, and being sensitive about it to boot, but ultimately I just emailed my boss and told him "I don't think this is going to happen in the time frame we've set out."

Losing 70+ pounds in the space of 30 days will almost definitely kill me. I've thanked him for his offer, and told him I am still willing to try to lose weight, but it won't be by mid-January.

*Fingers crossed he keeps the money on the table*