Maverick....
If you want a solid, fast growing, "healthy food" franchise... you might want to take a look at Bibibops. Its moving fast. Similar to a CMG in the setup. I've eaten there several times and its outstanding. Excellent food quality, and about as healthy as you're going to get. Millennial's love em. Put one of these in a college town with foot traffic.... it'll be a cash cow.
About $400K-$900K
http://bibibop.com/
https://www.qsrmagazine.com/news/bibibop-asian-grill-open-14-new-locations
Yeah pizza and burritos I understand, but bowls of granola with fruit and peanut butter? I don't know
well, you can stop wondering. No.Yeah pizza and burritos I understand, but bowls of granola with fruit and peanut butter? I don't know

That is the primary reason why someone looks at a franchise. A proven model.
I'd have to agree with this. The entire franchise model is based on the fact that they have a system that is working. You aren't buying the 'business' you are buying the 'system'.
In your due diligence you will get all the financials and pro-forma information that will give you, or should give you the exact numbers you will have to make to hit your goals.
As with everything in life, you can expect out what you put in. A franchise is just a short cut to owning your own business. You are buying through the learning and experience curve.