Researchers from the Universities of Exeter and Plymouth in the UK  conducted a systematic review of complementary therapies for reducing body weight.  

Literature was searched up through 2005 on Medline, Embase, Amed, and the Cochrane Library, along with hand-searches of relevant medical journals and bibliographies of identified articles. Data from RCTs and systematic reviews, which based their findings on the results of RCTs, were also included.

Six systematic reviews and 25 additional RCTs met the inclusion criteria and were reviewed. The evidence gathered related to acupuncture, acupressure, dietary supplements, homeopathy and hypnotherapy.

Except for hypnotherapy, ephedra sinica and other ephedrine-containing dietary supplements, the evidence was not convincing.  For these interventions, small effect sizes were found, as compared with placebo.
These researchers concluded that for most complementary therapies, the evidence for reducing body weight was not convincing.  However, hypnotherapy, E. sinica and other ephedrine-containing dietary supplements led to small but significant weight loss.
However, the intake of E. sinica and ephedrine is associated with an increased risk of adverse events, leaving hypnotherapy the only effective intervention of note.
Citation:  Pittler MH, Ernst E. Complementary therapies for reducing body weight: a systematic review. International Journal of Obesity (Lond). 2005 Sep;29 (9): pp. 1030-8. [email protected]