Should there be a Geekhack weight-loss Pool?
I like it. I'm doing a weight loss pool right now with friends and can confirm it may promote bad habits like eating at too much of a deficit, too much exercise or bodybuilder/wrestler style weigh-ins which will leave you weak & dehydrated. That said, it was an amazing catalyst to get 7 overweight guys focused on losing weight. I'd suggest removing the money element out of it so people aren't in a "do anything it takes to win" type of mindset, also it's not especially hard to photoshop a picture of a scale if you know what you're doing. Some friendly competition with the prize of bragging rights sounds like a good time.
Here are the rules my friends and I are currently using:
-The person who loses the most percentage of their body weight wins
-8 week weight loss period
-Weigh in every Friday AM - technically this isn't necessary considering the point below but it keeps people motivated and accountable.
-The last Friday weigh-in of the 8 weeks is the only number that matters
-Must take a photo of the scale every weigh-in (use the same scale the entire 8 weeks)