geez, i don't doubt that you have not experienced meth "addiction" firsthand, but to conclude that the symptoms others label as "addiction" or "tolerence" are entirely a function of sleep deprivation and poor nutrition does not take account any emperical information other then your own experience.
there is plenty of scientific evidence as well as plenty of antedotal evidence showing that amphetamines can cause receptor down regulation, which in turn leads to tolerance and depressive symptoms when usage is suddenly terminated.
for instance just type "amphetamine receptor downregulation" into google.
on just the first page alone you get these hits from reputable sources which seem to indicate there are indeed pyschiatric/physiological effects from amphetamine withdrawal.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8753884&dopt=Abstract (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8753884&dopt=Abstract)
http://www.nature.com/cgi-taf/dynapage.taf?file=/npp/journal/v14/n5/abs/1380426a.html (http://www.nature.com/cgi-taf/dynapage.taf?file=/npp/journal/v14/n5/abs/1380426a.html)