Fat burners are easily some of the most widely used fitness supplements on the market. A decade ago, fat burners were exclusively used by bodybuilders, physique models and competitive athletes to make weight in time for a competition, fight or show.
Today, they are used by pretty much anybody looking to lose extra weight as quickly as possible without losing excessive muscle. The transition to a broader market supplement has been helped a lot by the growth of natural fat burners. Unlike drug-laden, dangerous, sometimes deadly fat burners of the past, high quality modern fat burners use natural ingredients to safely promote body fat loss, reduce appetite, and increase energy levels.
The quality of fat burners on the market today varies a lot. Even so, we can say with certainty that a great many of them really work; the best stim-free fat burners on the market right now can definitely help you lose weight and keep muscle without causing serious side effects.
But what happens afterwards?
What happens to your body once you stop taking fat burners?
To answer this question, we need to take a closer look at how fat burners work and how long their effects last. We can then discuss what is likely to happen once you stop taking a fat burning supplement. If you have any questions about specific fat burners, please post them in the comments section at the end.
How do fat burners work?
There are hundreds of different ways that different fat burning substances work to promote weight loss. The best fat burner will utilize a handful of different natural substances to accelerate weight loss and promote better body composition along different pathways. This is the most effective way to supplement for fat loss, as it makes sure all bases are covered, and you tend to get a synergistic effect between different approaches.
One of the most important ways high quality fat burners work is by increasing lipolysis – the burning of stored fat for fuel. There are various substances out there capable of directly promoting the release of stored fat for use as fuel; Forskolin and EGCG are two that spring to mind here. These substances are known to stimulate fat loss indepedently of exercise, which makes them true fat burners.
Another important way that fat burners work is by suppressing appetite. There’s actually a few different ways to do this. Cheap diet pills and weight loss pills tend to stuff you full of stimulants like caffeine; these sitmulants suppress appetite by manipulating your neurotransmitters. While effective, this isn’t the healthiest or most sustainable way to manage appetite. Top-tier, high-spec fat burners will typically use slow digesting, water soluble fibers to create a feeling of fullness rather than trying to keep you hopped up on stimulants.
The best fat burners will also actively help preserve muscle mass during periods of intensive training and caloric restriction. Training more intensely on fewer calories is normally a recipe for rapid muscle loss (as well as even faster fat loss). Unfortunately, athletes routinely need to cut weight rapidly, be it to make weight for a fight, a weightlifting competition, or a bodybuilding contest. This often results in some loss of lean muscle mass. Minimizing that loss is vital to performance; it can make the difference between winning and losing on the day. Professional qualuty fat burners can drastically reduce muscle mass loss through the use of substances like HMB which prevent muscle catabolism.
Finally, we come to energy and fatigue. All good fat burners should contain something to boost energy levels. If they are a stimulant-free fat burner, then instead of caffeine they should use vitamins and herbal extracts to raise energy levels. Dieting invariably causes fatigue, lethargy, low mood, and loss of motivation. It is therefore vital that a fat burner help keep you energized and motivated in the gym while you train on an empty stomach.
Because effective fat burners have such broad effects on the body, you might feel very different once you stop taking the fat burner in question. This is especially true if you have been taking a fat burner or weight loss pill for a long time, as your body will have gotten used to the extra support it gets every day. But before we look at what happens when you stop taking a fat burner, it’s worth looking at how long fat burners typically stay in your system.
How long does it take for a fat burner to get out of your system?
How long a fat burner stays in your system ultimately depends on the fat burner in question, what ingredients it uses, what the doses are, and other factors relating to your diet and lifestyle.
Every substance has its own elmination half-life. How long a fat burner takes to get out of your system therefore depends on the ingredients and their doses. Some ingredients may be out of your system within a couple of hours, others may take days. Larger doses will take longer than smaller doses.
Other factors which control how long fat burning supplements stay in your system include your water intake, your diet, use of saunas and steam rooms, your body size, and your specific metabolism.
For example, drinking plenty of water will help flush a fat burner’s ingredients out of your system faster, as will using a sauna. But larger doses of ingredients with longer half-lives will take longer to clear out your system completely.
In almost every case, synthetic chemicals and pharmaceutical based fat burners – the kind of cheap diet pills you see advertised on late night TV – will take longer to clear from your system than natural supplements because the body simply handles natural substances better.
Generally speaking, a good quality fat burner will stop having acute effects after 4-5 hours, and will generally be present in minimal amounts after 24 hours.
What happens after you stop taking a fat burner?
So what happens when you stop taking fat burners?
In most cases, the main effects of a fat burner will wear off after about 2-3 hours. Depending on the ingredients used, you may still be experiencing suppressed appetite, increased lipolysis or higher energy levels for 5-6 hours after taking a dose. But this only really applies to the most effective fat burners; more often than not, you no longer experience the benefits 5 hours after taking a dose.
One thing that usually happens once a fat burner has worn off is a slight energy crash. It is very common for people to experience fatigue and poorer cognitive function when they stop taking fat burners. If you have been using a fat burner with caffeine for several weeks, then the first day after you stop taking the supplement can be tough. It may be several days before you start feeling ‘normal’ again as you get over caffeine withdrawals.
The fatigue people experience ehwne they stop using fat burners isn’t just due to caffeine. Many fat burners use several different ingredients which contirbute to higher energy levels, enhanced cognitive function, and increased motivation. If you suddenly stop taking these ingredients, you can feel sluggish, slow, and tired.
Another common side effect people experience when coming off fat burners is increased appetite. Top weight loss supplements will generally contain ingredients which gently keep your appetite under control, either by increasing feelings of satiety or by limiting hunger signals in the brain. Either way, stopping a fat burner can result in hunger coming roaring back, which could clead to your weight rebounding.
Weight rebounding – where you put on all the weight you lost while dieting – is sadly one of the most common things to happen when someone stops taking fat burners, weight loss supplements or diet pills. This generally happens more often with cheap fat burners stuffed full of stimulants and synthetic appetite suppressants, and less often with high-quality fat burners you take over long-periods of time (which makes the weight loss more sustainable).
Finally, there’s muscle loss. This is one of the worst side effects of coming off high quality fat burning supplements. The best fat burners will provide some protection for muscle mass; stop taking the supplement, and that protection goes away. If you continue to diet and train intensely, muscle mass loss can happen quite quickly.
Is there any way to avoid these side effects? What’s the best way to stop taking a fat burner to prevent side effects or weight regain?
What is the best way to get off a fat burner?
Coming off fat burners can cause a number of unwanted side effects. So what can you do to avoid them?
Here are the best ways to get off a fat burner without getting rebound weight gain or side effects:
- Increase intake of water and fiber to maintain fullness throughout the day
- Limit intake of sugar to prevent energy spikes and crashes
- Limit caffeine intake to a moderate amount spread out throughout the day
- Increase protein intake to maximize satiety and preserve muscle mass
- Reduce training volume to minimize muscle loss
- Reduce cardio and replace with resistance training or HIIT
Follow this advice and you should avoid most of the worst effects of coming off a fat burner. Of course, the best way to retain your gains and prevent weight rebounding is to use a professional-quality fat burner and take it consistently alongside a well-planned, sustainable diet and training regime.

Pavel Sadovnik is a leading biochemical scientist with a PhD in biochemical engineering. He has spent decades working in industry as a chemist and pjharmaceutical consultant. He has extensive experience with the supplement industry, and specialises in supplement tsting and formulation consultancy. He is the Editor of NARSTO.