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August 11, 2009

Could dieting spike a drug test?

Extreme dieting might cause false positive drug tests, the New Scientist speculates.

Here's the theory: THC, the primary psychoactive component in marijuana, is fat soluble and traces of the drug accumulate in adipose tissue. So, maybe burning a large amount of body fat in a short time releases enough of those stored chemicals to deliver a positive drug test in someone who hasn't used the drug lately. There are anecdotal reports of rapid weight loss causing people to fail drug tests long after they stop smoking marijuana.

The New Scientist's conjecture was prompted by a new rodent study reportedly accepted by the British Journal of Pharmacology. Researchers found that a 24-hour fast doubled THC metabolite levels in rats compared to animals that were allowed to eat normally after the same dose.

Even if the study results prove robust, there are a lot of unconnected dots separating starved rats and dieters undergoing drug tests. Still, the fact that rapid fat breakdown seems to increase THC metabolites lends credence anecdotes about false positives linked rapid weight loss. Clearly, more research is needed.

I wish I could say these findings would strike a blow against the urinalysis-industrial complex, if they were ultimately confirmed in humans--but compulsory drug testing is about social control, not scientific precision. The drug testers are probably already scheming to impose mandatory fasting protocols to reach even further back into subjects' chemical history.

On the other hand, this line of research might help victims of false positives dispute the results in court. One study cited by Consumer Reports found that forty-one percent of Americans were dieting. 


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More importantly though, does this mean I can catch a buzz if I diet? Don't tease me like those acid dealers who promised flashbacks years ago...I'm still waiting on those!

New Scientist is to science journalism what the Daily Mail is to political reporting.

I couldn't find the BJP research paper on PubMed (it probably hasn't been published yet), but once it's made available I suspect it'll throw some cold water on that headline.

What methodology were the researchers using for their test of THC metabolite levels? Blood work? Urinalysis? Hair tests? And why would the levels at 24 hours matter, a timepoint at which THC's metabolites will be present entirely regardless of diet?

Drug tests, especially industry-grade drug tests over employment, are notoriously leaky, to say the least.

Whether dieting effects the outcome is beside the point to the overall crappyness of the product to begin with.

Technically this wouldn't constitute a false positive, because there's no standard for how recent the drug use has to be for a positive to be true. A positive because you smoked up three months ago is no different from a positive because you smoked up this morning.

Yes, that's incredibly stupid, but it's true.

Good point, J Train. It would still be a true positive. But what's the word for a true positive that falsely suggests that someone was using during a time when they were actually clean? Say you're being tested to keep your parole. It would only be a violation if you smoked marijuana while you're on parole. Evidence of having smoked marijuana before you got paroled shouldn't logically be a parole violation. Yet, the law is probably written so that a positive test is a violation in itself on the assumption that a positive test means current use.

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