On the prism diet, you abstain from any product with sugar as one of the first four ingredients on the list, and potatoes, and pasta and ALL bread (even whole wheat).
For six weeks I ate sandwiches at work made with rice cakes. Blech!
And in 18 weeks I went from 245 lbs to 190. I rode the STP that year and it was unbelievable how much easier it was (I’ve done every STP between 1991 and 2008)
I’ve done STP twice. Great ride. I have gone from 315 down to 245. Trying to get to 210 or so. Lots of protein, few carbs.