How do I determine if my niche is viable?

I want to do weight loss group coaching for my religious community. We have dietary restrictions and many customs and rules surrounding the foods we eat and the times we eat. I checked on line and don’t see anyone targetting this group. The weight of obesity in this group is high (higher than average). How do I check if it is viable? I think that it is similar to Jodi’s group – how did she determine that her church group needed her services? Thank you.