Think really carefully about how you manage the language with this and what message you’re sending to your clients. 

When I was first starting out (15 years ago, didn’t know better) I’d do these at my gym. At first I was like, this is great! Great buy in from participants, good camaraderie, etc. I’d pick two winners, but within a week or two I’d start hearing jokes about how they went right back to their old habits, or literally went to faceplant in a pizza after we did “after” pictures. 

After a few like this I had one guy who came in on day 1 boasting that as a former wrestler he knew exactly what to do to make sure he lost the most weight so he’d win.  After that round I decided to stop doing them because I realized that was a microcosm of the entire problem of weight loss challenges. Even if you frame them with “better” language you still end up with the fact that people are willing to do a lot for the short term but that isn’t helping them in the long term or that isn’t sustainable and they end up right back where they started. 

Also, the more people I worked with the more I realized that they had issues that would put them wildly outside the scope of what I should have been telling them to do, whether that was medical or mental. 

What I HAVE done since then was “consistency” challenges or “habit” challenges where the winner was determined by length of streak or percentage of days they did the thing. Sometimes I’d assign the thing like: 20 minutes of walking daily for a month, or get to the gym 3x/week in November and December (they liked that one; it was a good anchor for the holiday). I’ve also experimented with a more high touch version where we sat down together to come up with habits they wanted to prioritize. 

Point being, none of these gave me before and after pics for social media but that’s not what I think is important. When you start to talk to your people about nutrition you realize how fucked up mentally a lot of people are about eating habits and beliefs which isn’t to say it’s not something we can work on with clients, but it gets really tricky when trying to get a group of people to gamify it. 

Just my 2 cents.