Diet has always generated passion, and passion in science is an infallible marker of lack of evidence.
That sentence is from a wonderful review of diabetic diet cycles over the last 150 years. It’s by L. Sawyer and E.A.M Gale, published in Diabetologia (2009, vol. 52, pages 1-7, DOI: 10.1007/s00125-008-1203-9). Anyone with a serious interest in diabetic diets will appreciate the funny and philosophical style of the authors.