Phase 1 is the difficult part. I can't remember how long it lasted.
As you work into Phases 2 and 3, I think you'll discover it's how we should all eat anyway.
My schedule is a typical M-F workweek with Sat and Sun off. I found the afterwork non-high intensity rides under an hour were just fine during Phase 1, but to cope with long rides on the weekends I had to "carbo load" starting with Friday lunch and then go back to strict Phase 1 with Sunday lunch. My glycogen stores couldn't cope with the super strict part of Phase 1 for anything of extended duration. As long as I followed this regimen, I was OK. I did NOT try to change my exercise level or train with any added intensity during Phase 1.
Unfortunately, I don't know how that regimen would affect your insulin. Basically, South Beach focuses on lean protein and complex carbos, getting rid of processed foods and simple sugars.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.