When weaning T3 therapy it is best to give the patients every opportunity for their systems to come back up to give their bodies every opportunity to maintain naturally the temperature and clinical status that has been re-established artificially. Of course stress and fasting can decrease the conversion of T4 to T3. So, if patients are under a lot of stress that is likely to pass over a week or two, it is often better to wait until then before weaning. If the patients are under chronic stress that does not appear likely to change any time soon, then it is best to just proceed with the therapy as well as possible. Likewise, stringent dieting while the T3 therapy is being weaned, or after the therapy has been discontinued, might cause the patients’ systems to slow back down again. So, if patients are planning to diet to achieve some much-needed weight-loss, it is generally best for it to be done before the T3 therapy has been weaned. While on T3 therapy the “T4/RT3-preponderance-generating” effect of fasting on 5′-deiodinase is muted since the patients’ T3 is largely being supplied directly by mouth, essentially bypassing the function of the deiodinating enzyme (See p50 for discussion of T4/RT3 preponderance).