It might be worth going to a sleep doctor; sleep apnea can really fuck up your metabolism, not to mention causing unbelievable akrasia. I would say sleep tests are a GOOD THING, something everyone should do. I had sleep apnea for years. It was like some eldritch monster was sucking away my willpower and I wasn't even aware. Within a few months of getting my mouth guard, which keeps my tongue from blocking my airway while in REM, I lost thirty pounds and gained an enormous well of mental stamina. A small minority of the "metabolically challenged" may just have undiagnosed sleep problems.