The proof I was referring to is in the forms of clinical/scientific studies that doctors/scientists in the article refer to when explaining the nature of drugs in the body:The doctors contacted by The Chronicle agreed that drug residue can remain in fat for a short time, but not indefinitely. "The longest we know that THC (the active substance in marijuana) stays in the fat is about a month. For ecstasy and LSD, we're talking about a day or two," said Dr. Neal Benowitz , head of clinical pharmacology at UCSF.