"Euthyroid hyperthyroxinemia (EH) is defined as a condition in which
the serum total or, rarely, the free thyroxine (T4) concentrations are
abnormal without evidence of clinical thyroid disease. These changes
may be transient or persistent and may be associated with normal, low,
or high triiodothyronine (T3) levels."

Although, people with EH do not have clinical thyroid disease so
treatment is not indicated.  

Still, as the previous poster indicates, it's probably not a good
weight loss strategy.