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How Long Do Fat Burners Stay in Your System?

Isaac Robertson
Published by Isaac Robertson
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: June 4, 2023
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If you're here, you're probably trying to lose weight. As an experienced fitness coach, I can say fat burners are fantastic for speeding up your weight loss process and getting you closer to your beach body.

However, there's one crucial thing many people neglect to check when taking fat burners, and that's the length of time these supplements stay in your system. So, how long do fat burners stay in your body? Let's see!

Quick Summary

  • Fat burners stay in your body system anywhere from an hour to eight hours.
  • Supplements that help individuals shed off some unwanted weight are called fat burners.
  • Ingredients that are found in fat burners include caffeine, green tea extract, L-carnitine, chromium, yohimbine, and cayenne pepper.
  • For better results when using fat burners, eat healthy and regularly exercise.

What Are Fat Burning Supplements?

Fat burner in front of different workout supplements

Fat burners are dietary supplements designed to help you lose weight. If you’re not familiar with fat burners, let me introduce you quickly.

They’re supposed to:

  • Promote fat burning
  • Enhance weight loss
  • Impair fat absorption
  • Cause long term metabolic adaptations that enhance fat metabolism
  • Increase fat breakdown during your workout

How Do Fat Burners Work?

Excessive appetite and a lack of energy may get in the way of your fitness journey, so fat burners boost your diet and exercise efforts in a couple of ways.

High-quality fat burner supplements can decrease your appetite and increase your stamina at the same time, all while raising the temperature of your body so you can burn more calories, even while you're resting.

A fat burner's primary purpose is to break down your body's fat and use it as energy — the process known as lipolysis, usually during exercise. This process also involves triglyceride hydrolysis into free fatty acids and glycerol.

Fat burner supplements contain a combination of ingredients. Each ingredient plays a crucial role in breaking down fat.

The Most Common Ingredients in Fat Burners

Fat burner pills with language of chemistry

Naturally, every brand has its proprietary fat burner blend, but the most common ingredients in diet pills include:

  • Caffeine is the best-known stimulant that's easily absorbed with plasma concentrations. Caffeine is thermogenic that peaks about 30–90 minutes after ingestion, and its impact lasts anywhere between four and six hours.
    Caffeine increases the activity of your sympathetic nervous system, which further increases adrenaline release. Caffeine also increases released fatty acids from adipose and intramuscular stores.
    Moreover, caffeine enhances the availability of fatty acids for oxidation [1] which helps mobilize the fat your body has stored for energy, thus sparing the muscle glycogen.
    If you want to be in total control of your caffeine intake, you could take a caffeine-only fat burner, but I recommend you take one that can be stacked with other non-stimulant diet pills.
    And don’t let anyone trick you — drinking coffee is not the same as consuming a caffeine-rich fat burner supplement.
  • L-carnitine is found in high concentrations in red meat, but our bodies also produce it, though in lower quantities. It acts as a carrier molecule that carries long-chain fatty acids (LCFAs) into the mitochondria, where the fat is burned for energy.
  • Chromium regulates and enhances the metabolic action of insulin. This trace element also supports the metabolism of fat, carbs, and protein. As you may know, insulin resistance often leads to weight gain and fat storage.
  • Green tea extract is rich in catechin polyphenols.
    The most active and abundant of these compounds is the epigallocatechin‐3‐gallate (EGCG), which stimulates fat oxidation by inhibiting catechol‐O‐methyltransferase essential for the degradation of norepinephrine [2]. This leads to the increase in SNS stimulation, leading to elevated concentrations of catecholamines, which subsequently mobilize and oxidize the fat. Combined with caffeine present in green tea, it could potentially burn fat and increase fat loss both during exercise and while you're resting.
  • CLA, or conjugated linoleic acid, is typically found in red meats. Numerous fat burner supplements contain this ingredient as it’s known for its ability to help people lose weight by acting as an anti-obesity agent.CLA will help you decrease appetite, increase energy expenditure, increase fat loss and oxidation.
  • Cayenne pepper, or capsaicin, is one of the most commonly used ingredients in fat burner supplements. It's another stimulant that helps your body heat up and burns more calories.
    Moreover, it also increases adrenaline release, increases your energy, and helps you burn more calories.
  • Yohimbine is great natural fat burner and it comes from the bark of the Pausinystalia Yohimbe tree. It is also known as an aphrodisiac. It's popular in the fitness world as it blocks the alpha-2 adrenergic receptors that bind with adrenaline.
    This allows adrenaline to stay longer in your system, resulting in a bigger weight loss.

See how you can make your own fat-burner with these ingredients.

How Long Does a Fat Burner Stay in Your Body?

a bottle with fat burners spilled

Finally, we get to the main question — how long do fat burners stay in your system?

The answer to this question isn't simple and depends entirely on the ingredients it contains.

If you have a supplement blend packed with stimulants, its impact could last for much longer than a stimulant-free supplement.

However, long-lasting doesn't mean more effective.

The half-life of caffeine in a healthy person is around five hours, but depending on the person, this time could go anywhere from 1.5–9 hours. Half-time refers to the amount of time it takes the stimulants to reduce to half.

Please, remember that, in the case of many fat burners, more doesn’t mean better results. Taking more than the recommended dose won’t result in more weight loss, and you can easily cross the line.

So, how long do fat burners stay in a healthy system? Anywhere from an hour to several hours.

Even Healthy Individuals Can Experience Side Effects if They Don’t Follow the Instructions

“Not all fat burners are created equal. Some products use lower quality ingredients that are less bioavailable to the body. Also, some formulations are not balanced, resulting in unpleasant side effects such as digestive upset or jitters.”

- Kasey Nichols, N.M.D.

You could also experience:

  • Anxiety
  • Nausea
  • Panic attacks
  • High blood pressure
  • Exhaustion
  • Weight gain
  • Acute liver failure

Of course, using supplementation according to the instructions will only enhance your fitness journey.

Do Fat Burners Affect Kidneys?

A hand holding a kidney model

A high-quality fat burner shouldn’t affect your kidneys. However,  fat burners and diet pills can affect your kidney function in a couple of ways.

Overweight and obese people usually have much protein, so using diet pills, weight control pills, or fat burners pushes the kidneys to work harder and filtrate more byproducts, known as nitrogen byproducts.

Diet pills typically enhance rapid body fat loss and muscle gain, so again, the kidneys need to work harder to process all the nitrogen byproducts.

Finally, fats act as cushions for the kidneys, so you will affect your kidney health if you burn too much of it.

However, if you use high-quality supplements, losing weight can improve your kidney health by reducing filtration workload. On the flip side, losing weight rapidly may lead to kidney pain and worsen its condition.

Essentially, supplements shouldn't negatively affect your kidneys if used according to the instructions. But no matter what, be patient and go slowly, as losing too many pounds can be as bad as being overweight.

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The Final Verdict

Don’t let anyone fool you — there is no quick, easy, or magical weight loss pill that will do all the job. Diet and exercise are crucial for burning fat and losing weight.

You have to dedicate yourself to eating healthy and nutritious foods and challenging exercise. Moreover, it would help if you arm yourself with patience, as weight loss takes time.

But adding a high-quality fat burner supplement will help you speed up the process of getting your dream figure.


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