This study gives some indication as to what the chronic effects of caffeine ingestion are in terms of various "receptors" as defined by mainstream medicine. I attached a screenshot from the study, which summarizes the effects nicely. It's probably not a surprise that caffeine is an adenosine receptor antagonist as shown by the table, but some of the other effects are interesting as well. Caffeine is also a 5-HT1 / 5-HT2 antagonist, beta adrenergic agonist, nicotine antagonist, muscarine antagonist, GABA antagonist, and calcium channel blocker. I think, these properties of caffeine help explain some of its positive metabolic effects.
Caffeine was administered for 4 days and the human equivalent dose was about 7mg/kg. I am not sure if 4 days is long enough to be considered "chronic" but it is long enough to highlight some of the major beneficial pathways through which caffeine acts.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3437321/
Caffeine was administered for 4 days and the human equivalent dose was about 7mg/kg. I am not sure if 4 days is long enough to be considered "chronic" but it is long enough to highlight some of the major beneficial pathways through which caffeine acts.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3437321/