Thermogenic fat burners: Feel the burn or skip the hype?

If you've ever searched for ways to lose weight, chances are you've stumbled across supplements promising to shred fat or fire up your metabolism. Among the most popular are thermogenic fat burners, products marketed to help you burn body fat more efficiently.

With your average Coles packed with shelves of powders, capsules, and drinks claiming to be the best fat burner, it's natural to wonder whether they really work or even if they're safe. Let's take a closer look at the science, ingredients, potential benefits, and whether or not you should consider adding thermogenic supplements to your routine.

What are thermogenics?

The word thermogenic comes from "thermo" (heat) and "genic" (producing). In nutrition, thermogenics generally refer to substances that may increase calorie burn by raising your metabolic rate, essentially, the rate at which your body burns calories for energy [1].

Some thermogenics are found naturally in foods like green tea and chilli peppers, while others are formulated into dietary supplements [2][3]. The idea is that by slightly increasing your caloric expenditure, you may be able to reduce body fat over time. Some weight loss supplements even go as far as to claim fat burners will alter your body composition, alongside shedding the kilos.

Note that thermogenesis is a normal process in your body. Every time you eat, move, or even shiver, your body burns energy and generates heat. Supplements simply aim to enhance this process.

Types of thermogenics

Thermogenics can come from many sources, and they're often grouped into two broad categories:

Food-derived thermogenics:

• Caffeine (found in coffee, tea, and some chocolate)
• Green tea leaf extract
• Green coffee bean extract
• Capsaicin (from chilli peppers)
• Certain spices, such as ginger or cinnamon

Supplement-based thermogenics:

• Standalone fat burner supplements
• Thermogenic blends that combine multiple ingredients like caffeine anhydrous, acetyl-L-carnitine HCL, and raspberry fruit extract
• Flavoured powders and drinks

Some are stim-free (stimulant-free), relying on plant extracts like olive leaf extract, while others are caffeine-heavy for an energy boost.

Foods vs supplements

So, should you reach for a chilli-spiced meal or a vibrant, flavoured drink?

Both foods and supplements can play a role, but they're not equal:

• Foods – Incorporating thermogenic foods like green tea or chilli as part of a healthy eating drive is a low-risk way to gently increase fat oxidation and calorie burn. Whole foods also provide fibre, vitamins, and minerals, benefits which capsules or powders can't match.
• Supplements – Products often concentrate these compounds in higher doses. While this might sound like a shortcut to fat burning, it can also raise the risk of side effects, especially if you're already using other supplements as part of your weight loss program.

What are thermogenic supplements?

Thermogenic fat burners are marketed as dietary supplements designed to promote fat loss by increasing your metabolic rate or enhancing metabolism.

You'll find them in many forms, including:

• Capsules and tablets
• Powders you mix with water (often in flavours like peach candy rings or frosty big apple)
• Ready-to-drink blends
• Shots or gummies

These products contain active ingredients such as green tea extract, caffeine anhydrous, or bitter orange fruit extract. Some include added nutrients such as ascorbic acid (vitamin C), pantothenic acid, or citric acid.

How do thermogenics work in the body?

The theory is that thermogenics may:

• Increase caloric expenditure by raising body temperature slightly [1].
• Enhance fat metabolism by helping the body mobilise stored fat and use fatty acids as fuel [4].
• Potentially support energy during an exercise routine, which can further increase calorie burn [5].

For example:

• Caffeine stimulates the central nervous system, which could temporarily boost energy levels, alertness, and metabolic rate [6].
• Green tea supplements contain catechins that may influence fat oxidation [7].
• Acetyl L-carnitine plays a role in transporting fatty acids into cells for energy production [8].

However, increases in metabolism are generally modest. Thermogenics alone are unlikely to cause significant fat loss without lifestyle changes.

Why are thermogenics so popular?

From influencer shoutouts to shiny tubs labelled "#1 fat burner", thermogenics are everywhere. They appeal because they promise something many blokes want: an easier way to burn body fat.

The popularity is driven by:

• Marketing Language – Terms like "melt fat" or "torch calories" are catchy.
• Convenience – A scoop of powder feels easier than meal prepping or gym sessions.
• Sports Nutrition Culture – Many fat burners are sold alongside pre-workouts and protein powders, creating a sense of legitimacy.

But just because people think they work doesn't mean fat burners work to do much more than leave you with a lighter wallet.

What ingredients do fat burner supplements commonly contain?

Most fat-burning supplements include a mix of stimulants, plant extracts, and supportive nutrients. Common inclusions are:

• Green tea leaf extract contains catechins that may increase fat oxidation [9].
• Green coffee bean extract contains chlorogenic acid, sometimes linked with fat metabolism [10].
• Bitter orange fruit extract is a source of synephrine, often included in thermogenic blends [11].
• Raspberry fruit extract, also sometimes marketed as "raspberry ketones."
• Acetyl-L-carnitine has been linked to fatty acid transport [12].
• Conjugated linoleic acid (CLA) is a fatty acid marketed for body composition support [13].
• Olive leaf extract and other plant extracts.
• Added vitamins or acids such as vitamin C, pantothenic acid, malic acid, or citric acid.
• Artificial sweeteners or flavourings.

Is there a difference between fat-burning supplements and thermogenic supplements?

The terms are often used interchangeably, but there are subtle differences.

Fat-burning supplements are a broad category of products that include anything marketed to support fat loss, from CLA to hydroxycitric acid (HCA). Thermogenic supplements, on the other hand, specifically target increased caloric expenditure and metabolic rate by raising body heat.

In practice, many fat burners overlap and are marketed under both labels. And that's the point. It's largely all about marketing.

Do they actually help you burn fat?

Research suggests that some ingredients, such as green tea extract and caffeine, may modestly increase fat burning or slightly reduce body weight in some studies. In reality, most fat burners only produce small effects. Often, these effects are so small that they may not translate into visible changes in body fat for the average person. Essentially, it's often just the same as increasing your caffeine intake.

There are also limitations. Individual responses vary, and results depend heavily on overall diet, exercise routine, and lifestyle.

In other words, thermogenics may support weight management, but they're not a shortcut to long-term fat loss. Energy expenditure, lower fat percentages, and more muscle mass only come from regular exercise, twinned with a healthy diet.

Who can use thermogenic fat burners?

While many are marketed to anyone trying to lose weight, they're not suitable for everyone. If you're thinking about adding them to cut into your fat mass, you should hold still if you have any pre-existing health conditions, especially those related to cardiovascular health or blood pressure, or if you're sensitive to stimulants like caffeine.

Always check with a GP or qualified health professional before starting any dietary supplements, particularly if you're on medication. It's always better to be on the safe side to avoid any issues down the road.

Are fat burners safe? – Potential side effects and safety considerations

Because thermogenics often contain stimulants, side effects may include:

• Jitters, anxiety or trouble sleeping
• Increase heart rate or blood pressure
• Digestive upset (nausea, diarrhoea, cramping)
• Headaches or dizziness

Other considerations:

• Moderate doses are usually recommended. More is not always better.
• Combining multiple thermogenic blends or other fat burners can increase the risk of side effects.
• The long-term safety of many herb extract ingredients remains unclear.

If you experience side effects, stop taking the supplement immediately and seek advice from a medical professional.

A holistic approach to healthy weight management

While thermogenic fat supplements might sound tempting, they're not a magic pill and represent just one piece of the puzzle. Sustainable weight management is best achieved by:

• Following a balanced diet rich in whole foods, including lean protein, fibre, and healthy fats.
• Staying active with a consistent exercise routine that includes both cardio and strength training.
• Managing stress and getting enough sleep.
• Consider professional support if you feel stuck in your weight loss efforts.

Supplements may play a supportive role, but they're not a replacement for healthy habits. Think of them as an optional add-on, not a magical solution. In any case, before you get moving, it's strongly recommended that you set up a chat with your GP first. They can evaluate your plans and point you toward weight-loss options such as personal trainers, therapy, or dedicated programs like Pilot's Weight Reset Program. Working with professionals makes it infinitely more likely that you won't just reach your weight-loss and fitness goals, but that the results will be sustainable.

Image credit: Pexels