First, I'll just preface this by saying that I'm not a Nick Diaz apologist, I just find this potentially very interesting.
There's speculation that Diaz tested positive for THC in his prefight urine drug screen. Diaz is a self-admitted marijuana user. He also appears to suffer from social anxiety disorder and with the mounting pressures associated with UFC Primetime and many media obligations, it would not be surprising to hear that Diaz buckled under the pressure and smoked marijuana in the days leading up to the fight.
However, it's possible that he didn't smoke marijuana and it may represent a false positive urine test.
How you ask?
Diaz posted a picture on February 3rd in the evening (<24 hours before the fight) of his groceries, one of which was a Hemp-containing food substance.
Twitter / nick diaz: http://t.co/Ar08nQSp
(I apologize if the link doesn't work. Just check his twitter feed; it's the 2nd pic. Maybe someone can post it for proof.)
Now, ingestion of a single serving of hemp food product will not cause a false positive test. However, daily consumption for one week of around 7 tablespoons of hemp oil (100 mL) has been shown to cause false positive urine tests (>50 ug/L of cannabinoids).
Clinical Chemistry journal article reference: http://www.clinchem.org/content/49/7/1037.full
We are all aware that Diaz is an admitted marijuana user but we're also well aware that he's a health nut and enjoys organic foods and oils, including hemp.
I firmly support accountability when a fighter knowingly breaks the rules and tests positive for a banned substance like anabolic steroids but this may, in fact, represent an entirely different scenario. It's not even analogous to steroid-tainted supplements since he would not be deriving any incidental competitive benefit from the trace levels of THC in hemp oil.
Again, there are obvious behavioral patterns which suggest Diaz may have cracked and smoked weed. I'm just providing an interesting alternative before the entire MMA community collectively writes Nick off as the best mixed martial artist to have wasted his talents on pot.
Dr;tl: Hemp oil in moderate amounts can cause you to piss hot for weed. Nick showed photo proof of hemp-containing food the day before the fight. I was serious when I told you it's all a conspiracy, homie!