Melatonin is a potent immunomodulatory hormone whose activity is still poorly understood. Shutdown of endogenous production isn't really the concern. Dosing any hormone way above and beyond normal limits carries inherent risk, animal and medium-term human trials be damned. I still think both low and high doses are useful in certain contexts, but recommending megadoses to strangers on the internet for weight loss when no human trials have substantiated its (admittedly plausible) efficacy seems a bit rash.
See:
http://www.mayoclini...DSECTION=safety
http://www.ncbi.nlm....57/?tool=pubmed
I agree! I was eagerly searching for humans trials to substantiate the evidence and none was found. That is usually the case with non-patentable substances. I did find studies looking at the effects on peripheral nerve regeneration (my original interest) and they all concluded it was safe. I did come across
this letter which offered some ease:
Exogenous melatonin administration in animals has been shown to cause significant weight loss and lower food intake, intra-abdominal fat and appetite [19–22]. In contrast, to our knowledge, no clinical trials have evaluated the weight lowering potential of melatonin in humans, although it is recognized that melatonin administration is safe and well tolerated.
However, data from the VITamins And Lifestyle cohort study of western Washington, in which participants (n=15,655) com-pleted questionnaires about 10-year supplement use, diet,
health habits, height, and present and former weight, showed that after adjusting for confounding factors, melatonin supple-mentation was related to weight loss and less weight regain
[24]. Patients with obesity commonly suffer from multiple comorbidities, including sleep disorders, which can sometimes benefit from melatonin administration[25,26], andanincreas-ing number of studies using this substance have been carried out in recent years, also including obese subjects. We suggest that changes in body weight, appetite and food intake should
be included in current and future clinical trials of melatonin as a simple, inexpensive and practical means of gathering evidence for the potential benefits of this substance in obesity.
So, patients with 1. obesity or metabolic syndrome can also suffer from 2. sleep disorders and other problems like 3. dyslipidemia. There are studies showing that Melatonin alone can positively affect all three. I think it's a pretty novel substance to treat obesity in that it's non-stimulating. 5-HTP is also up there with melatonin and this combination probably deserves its own thread. However, nothing that I wrote was meant to be medical advice. I think anyone visiting this forum already understands that basic idea.