Its to do with not letting your body get used to a certain way of eating (i think! lol!).
I'm low carb all this week, next week I'm low GI, then the following week im high GI. After my first 3 weeks, I get a "cheat day" on the sunday, where I can eat anything I fancy! Obviously not gorge myself to death in it, but, if I fancy a curry and a nann, then I should have it!
After my initial 3 weeks I go onto 2 days low carb, 2 low gi, 2 high gi and then a cheat day.
I think my problem is my body realizes im low carbing and doesnt want to play, so I'm hoping that by mixing my week up a bit that'll help.
Plus it means that 2 days a week I could have a slice of bread, or a bowl of cereal, and some fruit. I get stuck for ideas when im fully low carbing - I find myself sick to death of looking at green veg, chicken and butter! lol!