I’ve been thinking about writing a book on this topic: “No overweight person eats well”.

By very definition of a person is overweight, they got there by eating poorly, and are continuing to do so. They have eaten more energy than they use, this energy storage in fat.

I think there are an infinite number of true statements you could make about unhealthy or overweight people. What makes for a good book or article is finding the true statement you can say that actually sways behavior. I'm skeptical your message would succeed in this

> They have eaten...

Notice the past tense there?