There is no evidence that the diet is an effective cancer treatment.[21] Macrobiotic diet – a restrictive diet based on grains and unrefined foods, and promoted by some as a preventative and cure for cancer.[22] Cancer Research UK states "we don't support the use of macrobiotic diets for people with cancer".[23] McDougall diet – a restrictive low-fat, starch based vegan diet devised by John A. McDougall.