My understanding is that fasting will not lower your metabolism like restricting calories does. (idmprogram.com)
It should come as no surprise that if eating less food can lower the amount of oxygen we use, and hence lower the metabolism, then eating more food could increase metabolism. (psychologyofeating.com)
Sleep deprivation lowers your metabolism, which in turn has shown to increase the risk of obesity. (ahealthblog.com)