Pastor Joe Wilcots knew it was time to lose weight when he glanced at a photo of himself at a church function and thought: "Who is that fat little man?"

He'd already noticed some members of his flock, at Disciples of Christ church about an hour from Jackson, Mississippi, were unhealthily heavy; one man weighed nearly 450 pounds. And that was hard to see. "As a pastor when you look out over the congregation and see people overweight, then you want to help them," said Wilcots.

So when his neighbors – a reverend and a doctor – asked Wilcots about introducing a weight-loss program to his church, he felt it was "going to be good for the body of Christ".

For four months, every week after Friday evening service, Wilcots turned his pulpit over to Dr Erica Thompson, a Jackson-based practitioner specializing in community health. The entire congregation took part. The first thing Thompson told them was that, based on state statistics, one in three people in the room was at risk of developing diabetes. The second thing she told them was that losing just a few pounds, 5% to 7% of their body mass, could prevent that from happening.