I was looking up mpb on wikipedia (listed as: Androgenetic alopecia) and under the section "Hair loss and lifestyle" it says this:
"Daily, vigorous aerobic exercise (as opposed to short workout periods designed to raise androgen levels and build muscle or more sporadic exercise) and a diet which is adequate yet more moderate in terms of fat/total calorie intake have been shown to reduce baseline insulin levels as well as baseline total and free testosterone, significantly lowering baseline DHT."
So vigorous cardio and low calories lower natural test. I never heard this before, only that there is a propensity to burn muscle. This along with other stuff I've read makes it sound like it is incredibly difficult to cut without gear.