[Dove]

The book in particular doesn't give a regimen -- it's more of a toolset approach. Here are your options, here are the goals they're useful for accomplishing, here are some tips, here are some dangers. I would definitely read it before embarking on a program (or even planning or choosing one).

You can also work directly with the author's foundation at https://idmprogram.com if you prefer.

With that said, he doesn't really talk about three to five day fasts much. It's kind of a suboptimal length. He talks about 24-48 hour fasts for weight and diabetes control, and 7-14 day fasts as cancer preventatives. The former is recommended multiple times per week, and the latter is recommended once per year. But again -- it depends on who you are and what your goals are.