How Do Fat Burners Work? (What They Are & How To Use Them)

How Do Fat Burners Work? (What They Are & How To Use Them)

How Do Fat Burners Work? (What They Are & How To Use Them)

Fat Burners

Many people ask us 'do fat burners work?'. The simple answer is yes, they certainly can. When trying to bring down body weight through healthy eating and exercise, adding in a fat burner can support the process of breaking down adipose tissue (fat). Here we address different types of fat burner and how and why they work.

What are fat burners?

'Fat burner’ is a fairly broad term which encompasses a whole host of supplements touted to support weight loss, specifically from fatty stores. The broad and diverse fat burner category includes pills, powders and liquids which might work through a variety of different mechanisms to support fat burning.

Of course, in order to lose weight, the most important thing is that an individual burns more calories than they consume. This is called a calorie deficit. However, there may come a point where energy balance has been adjusted several times and progress has still plateaued. Fat burners (both natural and synthetic) are food and nutritional supplements, have fat burning properties and can aid a healthy diet and exercise plan.

Here’s what you need to know about some of the most common compounds found in fat-burning supplements, so you can make the most informed decision about which is the best fat burner for you.

Thyroid support

The thyroid gland secretes hormones, including the 2 thyroid hormones (T3 and T4). The thyroid hormones have a huge influence on metabolic rate, and any thyroidal dysfunction can make it incredibly difficult to lose weight, even when in a calorie deficit.

Some supplements claim to support the thyroid to avoid downregulation of the thyroid. Thyrodrene by Fusion Supplements is one example. The supplement uses diiodothyronines which have been shown to increase overall levels of T3 (triiodothyronine) and T4 (thyroxine), resulting in increased energy expenditure/basal metabolic rate, reduced fat storage and enhanced performance. Fusion Supplements have also included iodine as the thyroid gland relies on this element as its fueling mechanism.

Topical fat burners

Topical fat burners are fat burners that are applied to the skin in areas where stubborn fat is stored, such as belly fat or 'love handles'. Most of these increase the temperature of the skin to promote fat oxidation in this area. Specific products vary, but some can be combined with sweat belts and/or used for cardio sessions to enhance this effect further.


Thermogenics are supplements that increase heat through metabolic stimulation. Popular thermogenics include green tea and capsaicin.

Some thermogenics, like yohimbine, increase the production of hormones including adrenaline, noradrenaline and dopamine, which could theoretically boost fat metabolism. If ingredients like yohimbine and caffeine cause you any sort of anxiety, we'd opt for capsaicin which does not have any reported side effects.

Green tea extract contains a high amount of antioxidants which provide many health benefits plus epigallocatechin gallate (EGCG), a substance that can boost metabolism. Green tea is a natural source of caffeine, but as a lower dose that is more appropriate for those sensitive to stimulants.

Glucose disposal agents

Glucose disposal agents (GDAs) can aid the uptake of carbohydrate into the cells. Top GDA ingredients include berberine, chromium and ALA.

From a weight control standpoint, GDAs can increase insulin sensitivity. The hormone insulin is responsible for moving glucose into fat cells and a GDA decreases the need for insulin to be released. Overweight people on their weight loss journey may be dieting on low calories and carbs but, due to decreased insulin sensitivity, have an especially difficult time shifting the weight. This is where GDA style fat burner supplements can help.

Appetite suppressants

Appetite suppressants may reduce cravings or increase satiety around meals as food intake is lowered. This makes the diet more tolerable and easier to adhere to.

One ingredient suggested to reduce appetite is garcinia cambogia. The hydroxycitric acid content of which has been shown to improve fatty acid synthesis and in turn promote fat loss. Hydroxycitric acid has also been shown to work as an appetite suppressant. 5-HTP is another ingredient that has been shown to reduce how many calories a person consumes when calorie intake is not controlled.

Other supplements, such as fibers, reduce how much you are likely to eat by adding to the sensation of 'fullness' in the stomach, and also helping food move through the digestive tract. Look for powders containing ingredients like psyllium husk for this purpose.

Ketones and the keto diet also suppress appetite for some. Ketones from a source such as MCT oil added to a black coffee have been known to help people prolong fasting periods and reduce the desire to eat.

Do fat burners work?

As cliché as it sounds, a fat burner will work as hard as you do. Implementing a fat burner without making any other lifestyle changes might have a small impact initially if you have a high amount of excess fat to lose, but fat burners should be the final part of the puzzle alongside a diet and exercise program. Eating a balanced diet and exercising will also be key in improving body composition, while losing fat. To avoid the 'skinny fat' look as weight comes down, protein intake and resistance training can help you build muscle at the same time for a more toned and hard look. Protein powders and natural muscle building supplements can be stacked alongside a fat burner for this purpose.

How do fat burners work?

How fat burners work varies hugely from ingredient to ingredient. Common mechanisms of action include raising body temperature, acting as stimulants, increasing mobilization of fatty acids and/or reducing cortisol. Some fat burning formulas will attempt to tap into a number of these at once for increased efficiency.

How to take fat burners

Take your fat burner according to usage directions to support a weight loss protocol which involves placing you in a calorie deficit, either by reducing calorie intake, increasing expenditure through cardio, or a combination of both.

Overuse of caffeine and similar ingredients can lead to high levels of cortisol (the stress hormone that in high levels can break down muscle and cause fat storage). Adding to this side effect, your body can respond by slowing down your natural metabolic process to compensate. If using fat burners as part of an extended diet phase, such as a competition prep, it may make sense to cycle them. If you are able to implement a diet break, you could come off any fat burners then to reduce stress and inflammation before pushing for more fat loss.

When to take fat burners

Some fat burners have an effect that means they are best taken at strategic times. For example, some work best on an empty stomach, some can be taken before cardio or workouts, and some might be designed to use before bed. The product should advise on the best protocol!

Fat burners with any sort of caffeine, synephrine, yohimbe or similar ingredients in them will help raise your energy and kick start any fat burning. This might be first thing in the morning when you wake up, or you could take it 30 minutes before a workout as a pre-workout. These fat burners are categorised as “Stimulant fat burners”.

Fat burners with appetite suppressing properties should be taken at your hungriest point in the day – the time when you struggle with the hunger pangs or cravings. One strategy is to take it 30 minutes prior to a meal so you feel more satiated. These are generally non-stimulant thermogenics, and the effects can be subtle but a better choice if you are sensitive to caffeine or have high anxiety levels.

Fat burners shouldn’t be the “go-to” method when you start your weight loss regime. Ideally, these should be taken in the last few weeks of your diet to help lose those last few lbs. and % body fat.

Are fat burners safe?

Fat burners are safe provided they are used as directed by the brand and the product itself is approved for sale in the UK. Always buy fat burners through trusted stores and do not exceed the recommended dose or combine multiple products with stimulant effects.

Some fat burners might cause side effects that some find unpleasant, such as increased heart rate, sweating, or jitters. If this is undesirable, opt for a fat burner, or stack of fat burners, that do not utilize stimulants for a thermogenic effect. Some we would suggest include l-carnitine, CLA and chromium. Avoid caffeine and yohimbine.

If fat burners are purchased online, or from a less reputable source such as your local gym, ingredients might not be approved or regulated by the food and drug administration. If you are unfamiliar with the brand name or the claims seem too good to be true, do your own research first.

Are fat burners worth it?

Our conclusion If you are really looking to get everything you can out of a fat loss phase, we'd certainly suggest a fat burner a good investment towards the latter stages of a fat loss plan.

As we have discussed, the most important part of a weight loss/body fat loss plan is hard work, training and smart nutrition plan. But you can incorporate fat burners to help maximise your efforts. Fat burners have been shown (in both animal and human studies) to boost energy and increase metabolism which can aid oxidation of fat.

To get the most from synthetic and natural fat burners, it is best to include them as part of a balanced, healthful diet. Do not rely on them to burn fat on their own or assume that eating a new food will produce instant results.

Combine a good diet, exercise and supplement plan to help your reach your goals.


Are fat burners healthy or dangerous?

Fat burners are strictly regulated in the UK, meaning anything purchased from a reputable brand or reseller is considered safe at the recommended dose. To use a fat burner safely, always take as directed and, if sensitive to stimulants, you may even use a half dose initially to assess tolerance.

How long do fat burners stay in your system?

The duration a fat burner stays in your system can vary massively. Stimulants like caffeine have a half life of 6 hours, whereas cardarine has a 24 hour half life. If a supplement suggests taking one serving daily, this is what we would suggest for best results.

Should I take fat burners on non workout days?

Fat burners can be taken daily for best effects. If the fat burner is stimulant-based, take before your first meal in a morning (especially effective if doing any kind of fasted cardio). This will assist the body's ability to burn fat without having any negative impact on sleep.

What happens if you take fat burners without working out?

Fat burners can still be used without working out at a gym. By eating fewer calories and increasing energy expenditure (this might just be from increasing step count and NEAT). Dietary supplements such as fat burners are not only reserved for high level athletes and bodybuilders!