THC is fat soluble and whenever you smoke marijuana THC metabolites get stored in your fat cells. A metabolite is a product of your body’s metabolism. And how long marijuana stay in your system? Some of these metabolites pass through your system very quickly, as fast as 24 hours. The ones stored in your fat cells can take weeks to exit your body. The fact that THC is fat soluble and stored in fat is the clearest reason why detox kits are such scams. They claim they are “cleansing the toxins” from your body but they do not affect your fat cells at all. The only real way to get these metabolites out of your fat cells is to wait for your metabolism to take care of it.
Anecdotal evidence shows that if you are a light smoker the THC metabolites will be undetectable from your urine after about 13 days. Regular smokers show a detection window of about 45 days, and heavy smokers about 90 days. Your weight and speed of metabolism also play a role. If you are overweight the THC will remain in your body for a longer amount of time than if you are skinny. If you have a fast metabolism the THC will be metabolized and passed through your body more quickly. This means that an overweight person with a slow metabolism will test positive for a much longer time than a skinny person with a fast metabolism.
To speed up the process of passing these metabolites you need to burn fat. In other words you need to exercise. This means you will need to exercise, specifically cardio, as much as possible before you take your test. The more fat you burn the more THC will exit your body and the greater your chance of passing your test. If you’re not jogging three miles a day I would be forced to question your commitment to passing this test.
It is very important that you stop exercising completely two days before your test. When you’re burning fat you’re also burning THC metabolites which end up in your urine. If you exercise the day of the test you will have more THC in your sample than if you laid on the couch all day. Try to get as much exercise in before the cut off but don’t get overzealous by working out too close too the test. You will be doing yourself more harm than good.