So, there's a local fitness group that's conducting a weight loss challenge, and the winner gets a free trip. I'm scheduled for WLS (sleeve) in 9 days, but I really want to do the challenge.

Would entering the challenge be "cheating" since I'm getting surgery?

Are you planning on keeping your surgery a secret? Read the rules of the challenge.

By posting the question it is clear that there may be an ethical issue with joining the challenge. Anytime I have an ethical question I turn it around and imagine that I was joining a challenge and someone that had WLS was joining. How would that make me feel? If it makes me feel like they cheated then maybe it's cheating.

The idea of a free trip is very appealing and if it's not in the rules regarding WLS I would consider joining. Heck there may be two or three WLS challengers and you might have a true challenge on your hands:-)

My take is do what makes you feel good when your head hit's the pillow at night.

take care