When l go on a bulk and increase bodyfat, l am reducing my insulin sensitivity due to insulin receptors being downregulated. Does the reversal (upregulation) when l lose the body fat allow me to end up with the same number of insulin receptors l had at the beginning body fat or due to losing them once l have lost some permanently but also gained back a majority of them?

That is a tough question as l do not think anyone has really investigated all of the dynamics involved. Suffice to say, why play around with nature? l have found that if you want to encourage insulin sensitivity, take in lots of nutrients. especially potassium, from natural sources and not a lot of refined carb crap. Read more here: http://geocities.com/seabulls69/Type_II_Diabetes.html