So technically this could depend on how much fat you have to store the THC, but this has not been proven so weight or fat mass of a person does not come into this until it has been proven that there is a coloration between the fat mass of a person and how long the THC stays in your system.
Although this is the case and the THC stays in your body, it is not detectable forever and will not show up on a test forever.
There are the main ways to test whether a person has taken marijuana recently, by urine, by blood and by hair. Urine tests are the most popular and you can detect marijuana in urine tests for up to three months after it has been smoked or consumed.
Blood tests are the second most popular and the drug can be detected up to two months after taking it.
Hair is the least common way to test for marijuana and this will be in your hair for as long as it is on your head. If you are worried about this, you should cut your hair so that all of the hair on your head will have grown since the last time you have had the drug.
Of course, this all depends on your body and what takes two months for one body, may only take another body one month. This is because all of our bodies work in different ways.