Since I saw this at T. Colin Campbell's site, I suspect the diet Mr. Hale was following was similar to that which Drs. McDougall and Esselstyn promote - a low-fat, plant-based diet. It excludes all food of animal origin - no meat, fish, eggs, dairy - no cheese, yogurt, butter, etc. There is no added fat or oil. It is essentially a diet of whole grains, beans, vegetables, and fruits.
He said he ate a lot of cheese. In previous posts I noted that a 2001 Harvard review of the body of evidence at that time on dairy intake and prostate cancer found:
"[Consumption of dairy products] is one of the most consistent dietary predictors for prostate cancer in the published literature."