Article updated: 2021 Mar 30 / Author Leslie Griver, Robert Henry

How Long Does Weed Stay in the System Of a Skinny Girl

Weed will stay in the system of skinny girls or guys for up to 7 days. Small amounts of weed metabolites will remain in the system for a longer time.

But after seven days, they will not be detectable in the urine.

This is true for occasional smokers. The regular smoker will require more time to get weed out of the system.

In hair, weed can be detected for up to 3 years. The exact time depends on how often you cut your hair.

Skinny people and THC

Skinny people have an advantage – they have low body fat. Thus not much THC can stick to their fat cells.

Additionally, skinny people have a faster metabolism, and they can metabolize and remove weed faster from their systems.

So THC tends to stay in their system for a shorter period.

If you don’t know what is THC and why it “sticks” to fat, read this guide: THC Detox Guide. How To Get Weed Out Of Your System

Today, we’ll explain to you how long weed stays in the system of skinny girls or guys and what factors affect this time.

Let’s turn to science and calculate how long it will take to remove weed completely from a skinny person’s body.

Before we do any calculations, you need to understand several concepts.

How much THC is in the body

We inhale only about 50% of the formed THC. 30% is destroyed by burning. Others are lost in sidestream and incomplete absorption in the lungs.

Then only a small proportion reaches body circulation due to what is called the first-pass metabolism.

As a result, heavy users receive ~25% of THC while occasional users get ~12%.

Next, there’s a term – ‘half-life.’ It means the time it takes for half of THC in the body to be removed.

According to a study, the excretion half-life during the first five days following weed intake is approximately 31 hours for infrequent users.

And, for heavy users, half-lives would be longer than ten days.


There’s no way to calculate the amount of THC precisely. Everybody is different, and there are too many factors that influence THC metabolism. So we need to make some assumptions.

Let’s say we are calculating for the following person:

Jenifer: Skinny girl, occasional smoker. Jenifer smoked 1g of marijuana with 20% THC content.

That means there was 200mg of THC in a joint.


According to the research (that we mentioned previously), 24mg of THC will be in her body after smoking this joint.

According to another study that will help our calculations, if there is 27mg of THC in a joint, the amount of THC-COOH in a smoker’s urine would peak at 180 ng/mL after 4 hours.

Using cross-multiplication, after smoking 200mg of weed, the concentration of THC-COOH in the urine of Jenifer would be 1330ng/ml.

It will take two more days for the THC-COOH concentration to drop below 20ng/ml – the gas chromatography urine drug test’s cutoff level.

Conclusion: it would take about seven days to significantly lower the concentration of weed metabolites in skinny girls’ urine to below the detectable level of urine drug tests.

How to speed this process

There are three ways to speed up THC detoxification:

If you want to know more about this, read this guide: THC Detox Guide. How To Get Weed Out Of Your System

Since we are talking about skinny person burning body fat is not an option.

So we have only two options to speed up THC detoxification.

St. John’s Wort

This is the most famous herb for inducing enzymes responsible for the metabolism of THC. It is well researched, and several studies confirm its properties.

Take 300mg daily with food.

Activated charcoal

It is an absorbent. It will prevent THC metabolites in the intestines from being reabsorbed back into the blood.

Take 1000mg of activated charcoal twice daily.

Get guaranteed results - Pass your drug test with confidence!

Fast Marijuana Detox Kit

Fast Marijuana Detox Kit

The legal and guaranteed way to successfully pass a drug test in 60 minutes with confidence!

  • Same-day solution
  • Starts working in 60 minutes
  • Effective for up to 5 hours
  • Legal and undetectable
  • Moneyback guarantee
  • Safe for health

Green Fleets Premium 7-day THC Detox Kit

The healthy way to permanently clean your system of marijuana(THC), meth, alcohol, nicotine, and other toxins in 1 week.

  • Permanent detox
  • Takes 7 days to be clean forever
  • Cleanses urine, blood, and saliva
  • Legal and undetectable
  • Safe for health