Speaking from personal experience, with the same diet and level of exercise I see vastly different numbers. I've been through the process twice, the second time because I injured my back and wasn't able to exercise for two months. When I restarted my previous regime I found that my numbers stabilised at a far higher range than I'd achieved previously. I went through the same diet process again (for 2 weeks) after which I returned to the same regime. My numbers are now stabilised at the lower level that I'd achieved before.