Please Scroll Down to See Forums Below 
Quoted from Musclemonthly.com, writer is Bryan Haycock.
"The differences between ephedrine and Clenbuterol are important. For example, Clenbuterol is a very potent beta-2 agonist. As a result, within 14 to 21 days, the beta-2 receptors on muscle and fat cells will be drawn into the cell membrane to reduce their availability to Clenbuterol. Then, if you continue to take it, they will be disassembled all together, leaving you insensitive to Clenbuterol. It then takes at least 2-3 weeks for receptors to replenish themselves on muscle and fat cells. Once again, ephedrine is different with respect to down regulation. Ephedrine, being a much weaker agonist, does not cause rapid desensitization and/or down-regulation of adrenergic receptors. This allows ephedrine to be used effectively for many months. Despite these differences, both drugs should be tapered over the course of several weeks before discontinuing them. If you don’t, you will quickly replace the fat you just lost due to an increased appetite and a decreased ability of fat cells to mobilize stored fat."
The whole article is here http://www.musclemonthly.com/articles/001115/001115-haycock-howz-it-work.htm
"The differences between ephedrine and Clenbuterol are important. For example, Clenbuterol is a very potent beta-2 agonist. As a result, within 14 to 21 days, the beta-2 receptors on muscle and fat cells will be drawn into the cell membrane to reduce their availability to Clenbuterol. Then, if you continue to take it, they will be disassembled all together, leaving you insensitive to Clenbuterol. It then takes at least 2-3 weeks for receptors to replenish themselves on muscle and fat cells. Once again, ephedrine is different with respect to down regulation. Ephedrine, being a much weaker agonist, does not cause rapid desensitization and/or down-regulation of adrenergic receptors. This allows ephedrine to be used effectively for many months. Despite these differences, both drugs should be tapered over the course of several weeks before discontinuing them. If you don’t, you will quickly replace the fat you just lost due to an increased appetite and a decreased ability of fat cells to mobilize stored fat."
The whole article is here http://www.musclemonthly.com/articles/001115/001115-haycock-howz-it-work.htm
