Startup Idea : Online Weight-loss Competition Platform

Wouldn't it be nice to have a complete platform and resources for people to organize weight loss competitions in their local area? The idea isn't really unique because I know there are some websites out there that offer this similar idea but I think there are a lot of potentials in making it better and more fun. I can see there's a lot of demand for people to lose weight, especially in the U.S. and at the same time making extra money on the side. The idea is to create a site where people can create a competition and other people can join in. They can set the contribution fee themselves and the duration of the contest. Every 2 weeks or so, each participant is required to check in so everyone knows where they're at in the progress. Let me know what you guys think about this idea!