I’m Tanya Zuckerbrot, registered dietitian, mother of three and author of the F-Factor Diet. The “F” in the F-Factor stands for fiber. I’ve been in private practice for over ten years helping people lose weight. I came up with the F-Factor diet because what I found is that by adding foods which are good sources of both fiber and protein, people fill up, and by feeling full they tend to eat less throughout the day, leading to weight loss.