What Is A Fat Burner? Is It Safe? A Detailed Guide

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Fat loss is one of the most common health and fitness goals, yet, it is a goal that few successfully attain.

For decades now, scientists have been attempting to develop a pill to combat obesity. However, many supplement companies have created products that they claim cause fat loss.

Fat burning supplements appear to hold promise and are becoming increasingly popular, but are they actually effective?

This article will consider the fat burners, common ingredients and assess the research conducted on these products.

What Is A Fat Burner?

There appears to be an ever-growing number of supplements on the market to cater to every need and goal.

One such supplement is the fat burner pill. As the name suggests, these supplements have been designed to increase the rate of fat loss.

Fat burners are a type of supplement, containing substances that have been associated with an increased metabolic rate, reduced appetite, and enhanced fat burning.

It is suggested that the combination of these effects enhances fat burning and consequently causes significant weight loss.

There are several fat burner types available, including thermogenic, appetite suppressing, and energy-boosting fat burners.

Considering fat burners are fairly new, they have not yet been thoroughly researched. That said, many of the ingredients used in fat burners have been found to promote fat loss. 

How Does A Fat Burner Work?

Fat burners have been primarily designed to promote two fat-burning processes known as thermogenesis and lipolysis. 

1. Thermogenesis

It is not uncommon to find fat burners referred to as thermogenics.

Thermogenesis is the metabolic process that causes a significant increase in heat production and body temperature.

Many factors influence thermogenesis, including diet, exercise, and the environment.

A greater amount of energy and stored body fat is used up (1).

Many of the substances contained within fat burners have been associated with increasing thermogenesis.

Therefore, it is hypothesized that ingesting these supplements enhances thermogenesis, which consequently increases fat burning.

2. Lipolysis

Another process that fat burners claim to affect is lipolysis.

Lipolysis refers to the breakdown of stored body fat for energy purposes. During lipolysis, fat cells are broken down into fatty acids in order to provide the body with energy (2).

It is theorized that due to the increase in metabolism associated with fat burners, a greater amount of energy is needed.

As a result, lipolysis will significantly increase to ensure that the body has enough energy to maintain the raised metabolism.

By continually promoting lipolysis and demanding energy, the amount of body fat stored will substantially decrease.

Are Fat Burners Safe?

Fat Burner Types

While many products are regulated by the Food and Drug Administration (FDA), some supplements are not.

Some FDA-approved fat burners are safe to consume. However, some do not have FDA approval and may be associated with side effects.

The lack of regulation around certain supplements gives the manufacturers free rein to add whatever they like to their product.

As a result, question marks are surrounding the effectiveness and safety of these non-regulated fat burners.

Additionally, it is important to recognize that fat burners may not be suitable for everyone.

Many fat burners contain stimulating ingredients that may make them unsuitable for pregnant or breastfeeding or those with certain health conditions.

Lastly, it is important to note that supplements containing stimulants have the potential to interfere with sleep.

It is vital to consult a pharmacist or doctor first before taking any fat burning supplement.

Type Of Fat Burners?

There are many different types of fat burners, each containing its own unique blend of ingredients.

1. Thermogenic Fat Burners

As the name suggests, thermogenic fat burners contain ingredients designed to promote thermogenesis. By causing the body to generate more heat, more fat will be used up.

While thermogenic fat burners tend to be the most common, there are other types to be aware of. 

2. Appetite Suppressant Fat Burners

Appetite-suppressant fat burners contain ingredients that act on chemicals known as ghrelin and leptin. These chemicals play a key role in regulating feelings of hunger.

These ingredients balance out levels of ghrelin and leptin, causing a decrease in appetite, thus reducing the risk of overeating (3).

3. Stimulant-Free Fat Burners

As highlighted above, for many individuals, fat burners may not be suitable. Often this is due to the high number of stimulating ingredients contained within the supplement.

To cater to those sensitive to stimulants, stimulant-free fat burners cause a similar fat-burning effect without causing problems. 

4. Fat, Carb, and Cortisol Blockers

Finally, there is a range of fat burners that are sometimes referred to as blockers. These supplements negate the impact of specific macronutrients or hormones.

Fat and carb blockers are designed to release enzymes that prevent the digestion and absorption of carbs and fats.

This is particularly significant considering that carbohydrates tend to be the primary component of our diet. In addition, fats are high in calories coming in at 7 calories per gram.

Therefore, by reducing the absorption of these macronutrients, calories may be significantly reduced, thus promoting fat loss.

Cortisol blockers have an impact on the hormone cortisol, which is associated with stress. Studies have indicated that managing cortisol levels can be beneficial for weight loss (4).

Common Active Ingredients In Fat Burners

Ultimately, the value of these supplements hinges on the effectiveness of the ingredients used.

In this section, we will cover many commonly used ingredients in fat burners and assess their uses. 


Caffeine is a stimulating drug that is commonly consumed in food and drink. Not only does this substance provide a natural energy boost, but it also contains numerous antioxidants.

It has been the topic of many scientific studies over the years. For example, studies have suggested that caffeine may boost metabolism by 16% (5).

Furthermore, other caffeine studies suggest that it causes the body to burn more fat for energy (6).

These studies’ results help explain why caffeine is such a popular component of many fat burners.

Green Tea Extract

Green tea extract (GTE) is simply green tea in a concentrated form.

GTE is high in caffeine, and another substance is known as polyphenol epigallocatechin gallate. Research on both of these substances has highlighted their fat-burning qualities (6, 7). 

Furthermore, these two compounds complement each other greatly and enhance thermogenesis and consequent fat burning (8).

A meta-analysis study investigated the impact of GTE and caffeine on fat loss. Results showed that those taking GTE and caffeine burned 16% more fat than the control group (9). 


L-Carnitine is a compound that the body forms after consuming certain food like meat and dairy.

It plays a vital role in transporting the fatty acids to a part of the cell known as the mitochondria. The mitochondria burn these fatty acids to provide energy for the body.

By consuming L-Carnitine, it may be possible to optimize the transport of fatty acids and the function of the mitochondria. As a result, a greater amount of fat may be burned.

An analysis of L-Carnitine supplementation found that those who supplemented lost 2.9 pounds more than the non-supplemented group (10).


Chromium is another substance that occurs naturally in the body. This mineral has been found to enhance insulin sensitivity and regulate blood sugar levels (11).

It has also been associated with suppressing appetite. For example, one study found that taking chromium reduced calorie intake and appetite in overweight women (12).

Therefore, chromium is often added to fat burners to regulate blood sugar and influence control appetite.


Yohimbine is a popular supplement ingredient that has been linked with enhancing the rate of fat loss.

It is hypothesized that the yohimbine causes fat mobilization by inhibiting something known as alpha-2 adrenergic receptors.

A three-week study found that yohimbine caused a 2.2% reduction in body fat in soccer players (13).

However, it must be noted that results from studies investigating the effects of yohimbine on weight loss are mixed. For example, several studies have found no correlation (14).

Other commonly used ingredients that are used to enhance metabolism and suppress appetite include:

Fat Burner Side Effects

There are a number of potential side effects associated with fat-burners:

  • Agitation
  • Diarrhea
  • High blood pressure
  • Increased heart rate
  • Insomnia
  • Kidney issues
  • Liver problems

Do Fat Burners Actually Work

Fat-Burner Supplement Benefits

What the Science Says

While there may be a lot of research on specific ingredients, research on fat burner supplements is limited.

The research that has been completed has yielded mixed results.

One analysis concluded that fat burners do not have a significant impact on fat loss (14). In addition, due to the lack of regulation, some fat burners may be detrimental to health (15).

On the other hand, findings from other studies have promise. For example, one study concluded that fat burners increased thermogenesis and energy expenditure (16).

In addition, there is an array of evidence to suggest that many fat burner ingredients promote fat loss. For example, caffeine and GTE have consistently been found to have this effect.

Therefore, it is possible that fat burners can be a useful fat loss aid.

Ultimately, more research is required to understand the effects of these supplements on the body and fat loss.


Do fat burners cause muscle loss?

During fat loss, the body may also break down muscle tissue. This is why many individuals focus on consuming lots of protein during weight loss to minimize muscle loss.

Therefore, taking fat burners and accelerating fat loss may cause muscle loss. However, this can be minimized through strength training and adequate protein intake. 

How can I reduce stomach fat?

To bring about changes in body composition, a calorie deficit must be established. This is where calories are substantially restricted to cause the body to break down stored body fat.

Providing this deficit is maintained for a long time, a significant amount of fat will be lost. However, it must be noted that fat loss will occur throughout the body.

Some believe that by performing certain exercises, it is possible to cause fat loss in specific areas. An example of this is performing ab exercises in the hope of reducing stomach fat.

However, research has found that this is not possible (17). Therefore, the only method that will effectively bring about fat loss is a calorie deficit.

Can weight be lost quickly without exercise?

Considering the role that calories play, our nutrition has the biggest impact on weight loss. However, it is absolutely possible to bring about substantial weight loss without exercising.

However, exercising burns calories; therefore, it can create a calorie deficit and consequently facilitate weight loss. 

In terms of losing weight quickly, an extreme deficit will cause rapid weight loss. That said, a moderate deficit is recommended as it allows for a slower yet more sustainable reduction. 

Can fat burners be taken on an empty stomach?

Yes – in fact, for many fat burners, it is actually recommended to take them on an empty stomach. This will allow the fat burning substances to be absorbed more quickly by the body.

However, some people may find that taking a fat burner before eating causes side effects. If this is the case, take them at a time that causes fewer side effects.

Always read the product dosage guidelines thoroughly before taking fat burners.

Why should fat burners be taken?

Fat burning supplements are sold under the premise that they can boost metabolism and cause a greater fat burn.

The supplements contain ingredients that have been associated with increased body heat, regulating appetite, and enhancing fat utilization. 

Some studies have suggested that fat burners may enhance energy expenditure and aid fat loss. However, more research is needed to confirm this. 

When should fat burners be taken?

Often, the time that the fat burner should be taken depends on the type of fat burner.

For example, certain fat burner supplements are designed to be taken before exercise to enhance energy.

On the other hand, most appetite suppressing products will be taken before consuming a meal.

If unsure about timings, refer and adhere to the dosage guidelines on the product.


Much research has been conducted on the ingredients contained within fat-burning supplements.

Substances such as caffeine and green tea extract can cause an increase in thermogenesis and fat reduction.

However, research on the fat loss supplements themselves is currently in short supply.

Results from the research that has been conducted are currently mixed. However, there is some evidence to suggest that fat burners may increase energy expenditure.

Therefore, fat loss supplements may contribute towards weight loss; however, more research is required.

Be aware that there are a few concerns about the safety of a handful of non-regulated fat burners. Therefore, when selecting a supplement, choose an FDA regulated product.

Always consult a doctor before taking any new supplement.

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