Diamond said in an open letter to French published in the press last month that while the comedian had made an "astonishing transformation" by losing weight, an "obesity surgeon" had told the former TV-am presenter that "the easiest way to guarantee [that] sort of dramatic and consistent weight is to have a gastric band or a gastric bypass".
The comedienne has since insisted that she lost "a lot more" than the six stone Diamond estimated, and put the weight loss down to healthy eating and walking.
Speaking on a Radio 2 French and Saunders special to be aired tomorrow, French sarcastically says: "Thank you, Anne, for putting me right. Aren't I lucky that I have Anne Diamond telling me how to live?"
Jennifer Saunders asks: "Dawn, have you swallowed a gastric band?" French replies: "No, I have not." The duo then shout: "Shut up, Anne Diamond."
Diamond caused controversy in 2006 on Celebrity Fit Club when it was discovered that she'd had a gastric band.
She defended her decision by explaining that she "carefully researched" the procedure and spoke to others who had undergone similar surgery.
French and Saunders' Christmas Day Special will air on Radio 2 at 2pm tomorrow.