Beta 2 receptors etc

[krava]

I heard that after you do 45-60 min of aerobics, your beta 2 receptors close up and won't allow you to lose any weight. If you were using clen, the clen wouldn't allow the beta 2's to close up. If I can't use clen and allow my beta 2 receptors to close up after the 1 hour aerobics, under what conditions (food, sleep) etc will the beta 2 receptors open back up so I can do another 1 hour and lose weight? is it 12 hours etc? Let me know