Long associated with Oprah Winfrey, Bob Greene is an American exercise physiologist and certified personal trainer who has made his name writing about fitness and weight loss.

Bob Greene originally studied physical education at the University of Delaware, before completing a master's degree in exercise physiology from the University of Arizona.

In addition to his academic qualifications, Bob Greene is also a member of the prestigious American College of Sports Medicine, and the American Council on Exercise.

As an author he has written more than 10 books on diet, health and weight-loss, including two which he co-authored with Oprah Winfrey. Not surprisingly, he is a frequent guest on The Oprah Winfrey Show, has a radio show on her radio network, and is a regular contributor to O magazine.

Titles he has authored include:

Make the Connection: Ten Steps to a Better Body and a Better Life (with Oprah Winfrey)
A Journal of Daily Renewal: The Companion to Make the Connection, (also with Oprah Winfrey)
Total body makeover
Best life diet
Get With the Program! Guide to Good Eating: Great Food for Good Health

Despite his celebrity connection, his academic background ensures that his books are all based on solid scientific principles.