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Do Thermogenics Boost Fat Loss?

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Participating in regular exercise and a following well-rounded, healthy diet are the main two elements of any successful fat loss program.

Worryingly though, only around 20% of people that attempt to lose weight or improve their body composition actually manage to achieve their goals [1].

Over the last few years, the use of thermogenic foods and supplements has become popular – and rightly so. When used properly, these nutrients can boost metabolism and help you strip off body fat.

In this article we’ll tell you everything you need to know about not just which thermogenic nutrients are the best for you, but also which ones to avoid.

Here’s what we’ll cover:

  • What are thermogenics?
  • Which foods provide a metabolism-raising effect?
  • Which types of thermogenics you should avoid

What are Thermogenics?

Thermogenics are foods or supplements that increase the core temperature of the human body – a process called thermogenesis or ‘birth of heat’. This in turn leads to an increase in metabolic rate.

The way in which your body expends energy can be split into two main elements – the calories you use during physical activities, and the calories required to allow your heart to beat, muscles to assist in breathing and for your brain to function effectively.

The energy you need to ensure you’re vital organs work properly is referred to as your basal metabolic rate – and it accounts for a surprising amount of around 60-75% of your daily energy expenditure.

Practically all enzymatic reactions in the human body rely on thermogenic biochemistry, therefore if body heat goes up, so will your metabolism and ability to burn fat. When they are ingested they raise metabolism in a number of ways:

  • They increase the amount of energy spent for heat production
  • Boost oxidation and uncoupling of fatty acids
  • Stimulate central nervous system
  • Increase heart rate and blood flow


Key Point: Thermogenesis is the process of increased core body temperature.

Potential Thermogenic Benefits

The main benefit of these nutrients is that they can help you improve your body composition if used correctly. They can’t and won’t replace the need for a well-balanced diet and exercise program, but when used in combination can enhance your results.

They increase energy meaning that even though you may be on a calorie-restricted diet, you still have sufficient energy to train hard in the gym. This in itself can boost your progress and help you achieve your goals.

One independent study conducted in 2009 reported that when participants ingested a commercially marketed fat burner supplement, energy expenditure significantly increased [2]. This was measured using strict laboratory assessments such as resting oxygen uptake and respiratory quotient – both gold standard tests.

Likewise, a more recent study found that ingesting a commercial dietary supplement not only increased energy expenditure, but also focus and alertness – importantly without changes to blood pressure, heart rate or heart trace [3].

Some fat burner nutrients can curb your appetite too, meaning that you’ll eat less – seeing as though eating less calories than you burn off is key for fat loss, this really helps when trying to manage hunger etc.

There is also evidence that some thermogenics can enhance physical and mental performance, boosting your ability to exercise at higher intensities, or enhance concentration, focus and drive.

But some nutrients are better than others. Let’s have a look at what the research says about the best natural thermogenic nutrients…


Key Point: Thermogenics can boost metabolism, energy expenditure and curb appetite.

Most Effective Fat Burning Thermogenics

Green Tea

You can’t talk about quality thermogenics without mentioning green tea. This nutrient has been shown in numerous studies to boost metabolism and increase energy.

Used as a natural tonic in traditional medicine due to its high antioxidant content, green tea has been seen to reduce the risk of a number of long-term illnesses including breast cancer and metabolic diseases. The polyphenol content also has a protective role in fighting the risk of developing Alzheimer’s and Parkinson’s [4].

When you start dieting you’ll typically reduce your calories. The problem with this is that over time your metabolic rate starts to decrease, making it harder for you to lose fat – and keep it off. A study in the American Journal of Clinical Nutrition [5] found that green tea can offset this drop in fat burning potential by keeping your metabolism high during dieting – making fat loss easier. 

A number of other studies have found benefits of consuming green tea for improving body composition, but probably the biggest study – a met-analysis of 11 individual studies [6], found that this nutrient not only helped participants significantly decrease body weight, but also helped maintain healthy weight after a period of weight loss too.


Chili peppers are a hidden treasure for fat loss – presuming you can bear the heat. The active, alkaline compound found in the pepper called capsaicin, has long been touted as a fat burning nutrient due to its ability to raise body temperature.

These spices tend to be brightly coloured due to their caretonoid content, and have been shown to have anti-inflammatory properties and can alleviate the pain associated with arthritis, nerve pain and digestive illness. They have also been shown to reduce cholesterol and fat cells that can contribute to fat gain [7].

Cayenne pepper or ‘red pepper’ is the most scientifically tested spice, and studies show how good it is for fat oxidation. Cayenne has been found to boost metabolism and fat burning when added to meals, reduce meal intake by over 74 kcal, and decrease appetite too [8, 9].

Another spice, cinnamon, also has fat burning properties although it contains only small amounts of capsaicin. However, it does contain a number of other compounds that protect against high cholesterol, insulin resistance, diabetes and neurodegenerative disease.

Cinnamon helps to restore insulin sensitivity and combining this with its thermogenic properties has led to decreased fat mass and body weight in overweight volunteers [10].

Apple Cider Vinegar

This fermented vinegar is made from crushed and pressed apples. It results in a cloudy, amber colored liquid that has been found to improve bacterial conditions, urinary tract infections and both diabetes and cardiovascular disease.

The acetic acid content of ACV has been found to increase feelings of fullness and reduce the glycemic index of food [11]. Additionally, Japanese research has shown that drinking apple cider vinegar over a 12-week period prior to a meal resulted in lower body weight, body mass index, belly fat and waist circumference [12].


Key Point: Choosing the right thermogenic foods will help you achieve your fat loss goals.

Which Thermogenics Should You Avoid?

All of the nutrients we’ve discussed above are safe when used properly, but there are a number of other ingredients used in some supplements that are unsafe and should be avoided. These are dangerous and should be avoided at all costs.

2,4-Dinitrophenol or DNP is a thermogenic that disrupts cellular respiration, leading to an increase in energy expenditure.

Whilst this might sound good, the disruptive action causes severe oxidative uncoupling – this leads to increases in body heat so high that you can suffer from life-threatening hyperthermia. In fact, not only has it been banned by the FDA since 2003, it has also been responsible for over 60 deaths [13].

Another dangerous fat burner is ephedra. This particular ingredient mimics the action of the nervous system similar to that of adrenaline. Subsequently, it causes an increase in heart rate, blood pressure and dilates blood vessels.

Banned by the FDA since 2004, ephedra has been responsible for 64% of all adverse reactions to fat burner supplements even though it accounts for only 0.82% of herbal product sales [14]. It has also been responsible for 10 deaths, 13 permanent impairments, and a range of cardiovascular and neurological illnesses [15].


Thermogenics are foods or supplements that increase the core temperature of the human body. This leads to an increase in energy expenditure and metabolic rate.

A number of nutrients have been found to have a thermogenic effect, and when used properly these can lead to improved physical performance and body composition, reduced appetite and fat mass, and enhanced metabolism. Additionally they can improve mental performance, concentration and focus.


  1. Wing, RR et al. Long-term weight loss maintenance. Am J Clin Nutr. 2005; 82(1): 2225-2255
  2. Hoffman, JR et al. Thermogenic effect of an acute ingestion of a weight loss supplement. Journal of the International Society of Sports Nutrition. 2009; 6:1
  3. Outlaw, J et al. Effects of ingestion of a commercially available thermogenic dietary supplement on resting energy expenditure, mood state and cardiovascular measures. Journal of the International Society of Sports Nutrition. 2013; 10:25
  4. Weinreb, O et al. Neurological mechanisms of green tea polyphenols in Alzheimer’s and Parkinson’s diseases. J Nutr Biochem. 2004; 15(9): 506-16
  5. Hursel, R et al. Catechin- and caffeine-rich teas for control of body weight in humans. Am J Clin Nutr. 2013; 98(6 Suppl): 1682S-1693S
  6. Hursel R et al. The effects of green tea on weight loss and weight maintenance: a meta-analysis. Int J Obes. 2009;33:956–61
  7. American Chemical Society. (2012, March 29). “Improving Heart Health With Hot Pepper Compound.” Medical News Today
  8. Whiting, S et al. Could capsaicinoids help to support weight management? A systematic review and meta-analysis of energy intake data. Appetite. 2014; 73: 183-8
  9. Ludy, MJ et al. The effects of capsaicin and capsiate on energy balance: critical review and meta-analyses of studies in humans. Chem Senses. 2012; 37(2): 103-21
  10. Roussel, AM et al. Antioxidant Effects of a Cinnamon Extract in People with Impaired Fasting Glucose That Are Overweight or Obese. Journal of the American College of Nutrition. 2009; 28(1): 16-21
  11. Fushimi, T et al. Effect of acetic acid feeding on the circadian changes in glycogen and metabolites of glucose and lipid in liver and skeletal muscle of rats. Br J Nutr. 2005; 94(5): 714-9
  12. Kondo, T et al. Vinegar intake reduces body weight, body fat mass, and serum triglyceride levels in obese Japanese subjects. Biosci Biotechnol Biochem. 2009; 73(8): 1837-43
  13. Tainter, ML et al. Use of dinitrophenol in obesity and related conditions. A progress report. JAMA. 1933;101:1472–1475.
  14. Zaacks, SM et al. Hypersensitivity myocarditis associated with ephedra use. J Toxicol Clin Toxicol. 1999; 37(4): 485-9.
  15. Haller, CA et al. Adverse Cardiovascular and Central Nervous System Events Associated with Dietary Supplements Containing Ephedra Alkaloids. N Engl J Med 2000; 343:1833-1838