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In the world of fitness and weight control, several terms are thrown about with little understanding of their true meaning. Among these is the word 'thermogenic.' In this article, we demystify the concept of thermogenesis, discovering how it can help you lose unwanted body fat, improve your energy balance and achieve your wellness goals.
Table Of Contents:
The word thermogenic is of Greek origin and literally means heat (thermos) creation (genesis). In humans and other warm-blooded animals, thermogenesis is the process of heat production in organisms.
As such, a thermogenic compound increases a person's metabolism when taken into the body, increasing the body's energy expenditure, AKA heat generation.
There are two types of thermogenesis:
With non-shivering thermogenesis, the body creates heat without shivering, which is a normal reaction to the cold. Most of this internal heat is generated by burning a particular type of fat cell called brown adipose tissue (BAT).
BAT is unique because it has more mitochondria than other fat cells. It also has an abundance of a protein called uncoupling protein 1 (UCP1). The mitochondria in BAT are unique because they can transform energy directly into heat without moving through the usual ATP synthesis process. They do this by allowing protons to escape back into the mitochondrial matrix, allowing it to produce heat rather than ATP.
This type of thermogenesis is often triggered by exposure to cold temperatures. Norepinephrine, which binds to receptors on BAT cells and stimulates UCP1 activity and heat production, is released by the sympathetic nervous system when the body experiences cold. This procedure keeps the body's core temperature stable and prevents a dip brought on by cold weather outside. Exposure to cold temperatures and the production of norepinephrine are the triggers for non-shivering thermogenesis.
The energy used up during the digestion, absorption, and processing of nutrients from a meal is referred to as diet-induced thermogenesis or the thermic effect of food (TEF). The body uses energy to digest meals, absorb nutrients, and process them for use. The thermic effects of different macronutrients vary, with protein being the highest, followed by carbohydrates and then fats. That means food consumption, especially protein-rich meals, activates diet-induced thermogenesis.
Certain foods, drinks, and weight loss supplements have ingredients that may speed up metabolism and encourage fat burning. Examples of compounds that have been investigated for their potential to raise energy expenditure and encourage weight loss include caffeine, green tea extract, and capsaicin from chili peppers.
Increasing the rate at which the body burns calories by promoting thermogenesis is believed to assist with fat loss. As a result, supplements with thermogenic-promoting ingredients are promoted as fat-loss supplements.
The world of thermogenic supplements has drawn interest from those looking to increase their metabolism and start a path toward successful weight management and a healthier, more active lifestyle. Let's explore the three most popular categories:
Thermogenic fat burners are designed to boost your metabolism and encourage fat oxidation. The natural substances in these supplements are combined to promote the body's thermogenic processes.
The most common thermogenic ingredients are caffeine, green tea extract, capsaicin from chili peppers, and L-carnitine. These compounds are thought to boost energy expenditure, encourage lipolysis (fat breakdown) to release fatty acids, and produce more and alertness.
The main mechanisms by which thermogenic fat burners increase metabolic rate are stimulating the central nervous system and boosting norepinephrine release. This increases energy expenditure and might eventually help with body fat loss.
Thermogenic probiotics are a distinct class of probiotic supplements designed to alter gut microbiota composition, potentially altering metabolic processes.
Some research indicates that certain proteins of probiotics can positively alter the makeup of gut bacteria . This affects how energy is extracted from the foods we consume and the metabolic mechanisms that regulate weight management.
Certain foods have an extremely high thermogenic effect, boosting the demand for energy during digestion. To meet this increased energy demand, the body must burn calories. So, by adding these foods to your diet, you can increase your calorie burn.
Protein-rich foods such as fish, chicken, eggs, and protein shakes have a higher thermic effect on the body than fats or carbs. Finally, other ingredients in everyday foods, such as the capsaicin in chili peppers or the caffeine in coffee, can increase the body's internal temperature. We'll get into those more below.
Let's now dig down on the most common thermogenic ingredients. You'll usually find all or some of these ingredients in the most popular fat burners on the market:
Caffeine is the world's most used stimulant. It's also the most popular ingredient in thermogenic fat burners.
When you consume caffeine, you naturally increase the body's production of a neurotransmitter called norepinephrine. Caffeine's ability to trigger the production of norepinephrine leads to an increased reliance on fatty acids as a fuel source and may spare glycogen (stored glucose). This results in an increase in metabolic rate, producing greater energy to burn fat. The increased secretion of norepinephrine also results in the breakdown of fat cells (lipolysis) to be used as an energy source.
Caffeine's neuro-stimulating ability leads to greater alertness, delayed fatigue onset, and a reduced perception of effort. All of these factors can contribute to better performance when working out, which may lead to more strenuous workouts, indirectly supporting additional efforts to lose fat.
Caffeine causes the body to burn more calories even when at rest by speeding up metabolism. This increased energy expenditure may help create a calorie deficit, a key element of weight loss.
Research shows that as little as a single milligram of caffeine can help burn one-tenth of a calorie in the 24 hours after taking it . We can extrapolate from that that taking 250 mg may help you lose an extra 25 calories. Studies show that taking 3-5 mg per kg of body weight is appropriate for producing a metabolism-boosting effect .
A number of variables, such as dosage, individual sensitivity, and tolerance, influence caffeine's efficiency as a thermogenic fat burner. Dosages between 100 and 400 mg per day are frequently used in thermogenic fat burners. Consuming too much coffee might have adverse effects like jitteriness, an accelerated heart rate, and sleep difficulties.
If you want the benefits of caffeine without having to guzzle down energy drinks, check our article on the 7 Best Caffeine Pills.
Green tea, a traditional beverage recognized for its health advantages, has also won praise as an effective thermogenic fat burner ingredient. This is due to its high quantity of bioactive components, including catechins and caffeine.
Catechins are a type of plant compound known as flavonoids. The most abundant catechin in green tea is epigallocatechin gallate (EGCG). Researchers have discovered that this compound has a host of health-giving benefits, one of which is the ability to boost metabolism, promoting the burning of calories. Even though coffee has a higher level of caffeine than green tea, it can still burn fat due to its impact on several physiological systems.
Green tea catechins, particularly EGCG, have been discovered to boost thermogenesis by altering the enzyme activity that controls fat metabolism. They may also increase the activity of brown adipose tissue to produce heat. EGCG has been shown to increase hormone-sensitive lipase (HSL) production, an enzyme that releases fatty acids from adipose tissue, speeding up the breakdown of stored body fat into energy.
Green tea's catechins and caffeine seem to have complementary effects on metabolism, as shown in several studies on how green tea affects metabolism to promote weight loss. In fact, the thermogenic reaction may be amplified by caffeine since it improves catechin absorption. That's why caffeinated green tea supplements can raise energy expenditure, encourage fat oxidation, and perhaps aid in weight loss.
Other research shows that frequent use of green tea catechins may result in minor decreases in body weight and fat mass. In one study, obese study subjects who took a green tea extract every day for 12 weeks lost an average of 0.04 kg . Another study, over the same duration, produced a more significant average weight loss of 1.3 kg .
Studies on green tea supplements' impact on abdominal fat, which is frequently thought of as metabolically active and linked to health hazards, have also been conducted. According to some research, green tea catechins may help prevent the buildup of visceral fat .
While there is no single ideal dose that will always provide thermogenic effects, studies have frequently used amounts that are comparable to several cups of green tea per day.
To learn more about green tea specifically, read our article Is Green Tea Good For Weight Loss?
Capsaicin, the compound in chili peppers that gives it its hot kick, has been demonstrated to have qualities that can affect metabolism, energy expenditure, and fat oxidation.
Several physiological pathways allow capsaicin to provide its thermogenic effects. It activates brown adipose tissue, a kind of fat tissue that produces heat by burning calories rather than storing them. It has also been demonstrated that capsaicin stimulates non-shivering thermogenesis. As a result, energy expenditure increases, and there may be a drop in body fat.
Consuming foods or supplements high in capsaicin has been connected to a momentary rise in metabolic rate. It increases body temperature, with the increased heat boosting energy expenditure. Capsaicin may also promote the release of fatty acids from adipose tissue, increasing fat oxidation.
Studies on the thermogenic effects of capsaicin have produced quite impressive results. According to several studies, taking capsaicin supplements might cause slight drops in body weight and reduce body fat. In one study, capsaicin supplements resulted in an average calorie burn increase of 50 calories compared to a control group . Another study showed that the capsaicin group burned 10% more calories than the control group 24 hours after taking the supplement .
Research also suggests that capsaicin may aid in suppressing hunger and enhancing feelings of satiety. By lowering total caloric intake, this impact may indirectly aid in weight management.
Researchers have also examined how capsaicin affects abdominal fat, which is frequently linked to higher health risks. In one study, a dosage of 6 mg was shown to produce a slight reduction in waist measurement after 12 weeks of supplementation . According to that study, capsaicin may aid in reducing the buildup of visceral fat as well.
The tropical fruit Garcinia Cambogia, or Malabar Tamari, has become widely used as an ingredient in weight loss pills and thermogenic fat burners. Its key active ingredient is hydroxycitric acid (HCA), which is believed to increase metabolism, suppress appetite, and increase fat burn.
Researchers believe HCA inhibits citrate lyase, an enzyme that turns extra carbs into fat for storage. By blocking this enzyme, HCA may lessen the body's capacity to store fat made by dietary carbs. HCA may also affect serotonin levels in the brain, which may result in suppressed appetite and desires. This may help dieters to eat fewer calories and achieve the daily negative calorie balance needed for sustained weight loss.
It's been suggested that HCA will promote fat oxidation, encouraging using stored lipids for energy. A 2011 meta-analysis showed that taking a garcinia cambogia extract for between two and twelve weeks resulted in an average weight loss of 1% more than that experienced by the control group . In other studies, though, the effects are often modest and can differ depending on the dosage, the subject's reaction, and the study's methodology.
Some research indicates that using garcinia cambogia supplements may cause people to feel less hungry and eat less.
Garcinia Cambogia lacks the direct thermogenic qualities of caffeine or capsaicin, but it does have indirect thermogenic benefits on metabolism and appetite control that may help people lose weight fast. Check to make sure any garcinia cambogia supplements you are thinking about are standardized to have a consistent concentration of hydroxycitric acid.
Citrus aurantium, also referred to as bitter orange, has gained popularity as a thermogenic fat burner and weight reduction supplement additive. The bitter orange's active ingredients, especially synephrine, have been linked to potential impacts on metabolism and energy expenditure.
Synephrine is the crucial active ingredient in bitter orange. This plant compound stimulates the adrenal glands, increasing metabolic rate and energy to burn body fat. It is also thought to boost fatty acid release from adipose tissue, which could result in more fat burned and energy used.
Synephrine is believed to have similar effects to the compound ephedrine, which was banned in 2004 due to several heart-related deaths. Synephrine has not been shown to have the same negative cardiovascular side effects . According to some studies, synephrine may affect appetite control and decrease food intake, thereby assisting with weight loss efforts. The adrenergic, or ability to stimulate neurotransmitters, effects of synephrine may increase energy expenditure and metabolic rate.
According to research, consuming bitter orange extracts that feature synephrine may result in slight drops in body weight and fat . However, they can vary depending on dosage and personal response. Synephrine's direct thermogenic effects are not as strong as those of other thermogenic substances like caffeine or capsaicin.
Studies show that an effective dose of synephrine to achieve a thermogenic effect is 50 mg per day . This amount has been shown to produce an average increased energy burn of 65 calories per day.
Yohimbine, an alkaloid produced from the bark of the Pausinystalia yohimbe tree, is thought to affect weight management via several mechanisms. It can inhibit sympathetic nervous system receptors, resulting in greater norepinephrine release. This neurotransmitter can increase fat lipolysis and raise metabolism, potentially producing higher calorie burn.
Yohimbine's effect on alpha-2 adrenergic receptors may promote fat oxidation by enhancing the availability of fatty acids for generating energy. Some research shows that yohimbine may also affect appetite management, lowering calorie intake and assisting with weight loss goals .
Individual reactions to yohimbine can differ depending on the dosage, tolerance, and general state of health. Some people could develop negative side effects, including elevated blood pressure, anxiety, and heart rate.
Thermogenic supplements may have unwanted side effects, particularly if misused or in excess. It's crucial to keep in mind that every person will react differently, and some may be more susceptible to the side effects of thermogenics than others.
Here are the most common possible adverse effects linked to thermogenic supplements:
Increased Blood Pressure and Heart Rate: Stimulants like caffeine, yohimbine, and synephrine can elevate both heart rate and blood pressure.
Jitters: Thermogenic stimulants may produce a wired, jittery reaction in some people, especially those sensitive to substances like caffeine.
Sleep Disruption: The stimulants in thermogenics may result in insomnia and impaired sleep quality and quantity. For this reason, you should not take a thermogenic before bedtime.
Gastrointestinal Upset: Some people may suffer from gastrointestinal problems, including stomach upset, gas, bloating, and diarrhea.
Headaches: Some people sensitive to coffee or other stimulants may get headaches or migraines after using thermogenics.
Dizziness and Lightheadedness: These symptoms might be brought on by a combination of an elevated heart rate and possible dehydration from using thermogenic supplements.
Tolerance and Dependence: Over time, consistent usage of thermogenics may cause the body to become tolerant to their effects. As a result, people might require bigger doses to have the same results, which could eventually result in dependence.
Medical Interactions: Some thermogenic ingredients may interact with medicines, particularly those that treat blood pressure, heart problems, and other medical diseases.
Allergic Reactions: Some people may have allergic reactions to one or more of the ingredients in a thermogenic supplement.
Dehydration: Thermogenic supplements can increase the body's temperature, potentially leading to fluid loss. If that fluid is not replaced, dehydration could result.
To ensure quality and safety, choose thermogenic supplements from reliable sources. Start with smaller doses to determine your personal tolerance and reaction. Observe the dosage recommendations listed on the product's label.
To reduce the risk of negative effects, avoid combining different stimulants or caffeine sources. Be aware of your body's reaction and stop using it if you see any adverse effects.
At SET FOR SET, we've spent literally hundreds of hours doing that research. Our top recommended thermogenic supplement for both men and women is PhenQ. All of its products are manufactured in an FDA-approved facility.
Their fat-burning formula is not only formulated by nutrition specialists, it's undergone several independent scientific studies to prove its effectiveness. It's combination of premium, 100% natural ingredients such as capsimax powder, caffeine anhydrous, and more make it one of the best thermogenic supplements on the market
Let's answer some more of your questions before we close out.
A thermogenic diet consists of foods that speed up metabolism and encourage fat burning, such as high-protein diets, spicy foods, and fat-burning supplements.
The best time to take a thermogenic fat burner is about 30 minutes before your first meal or first workout of the day. Your metabolism will rise was you eat breakfast or get moving, so a thermogenic fat burner will accelerate that process.
Yes, thermogenic fat burners can elevate your internal body temperature without exercise, but the weight loss results will be limited. For best results, combine fat burners with a regular exercise regimen, a healthy diet, and lots of sleep.
For body temperature elevation, a thermogenic fat burner starts working immediately after you take it. Increased metabolic activity starts to kick in about 30-60 minutes as your body digests the supplement. However, long-term fat loss results and timing depends heavily on other lifestyle factors
Many thermogenics, such as caffeine and bitter orange extract, are also stimulants and can keep you awake at night. Individual ingredients like the catechins in green tea won't keep you awake, but they're typically combined with other stimulating elements in thermogenic fat burners. As such, it's best to avoid taking thermogenic supplements at night.
The key to maximizing thermogenic supplements is not simply including them in your routine but making informed product decisions. The market is flooded with thermogenic supplements claiming to have the key to quick weight loss, improved body composition, and enhanced fitness. To find the ones that really do what they claim, you've got to do your research.
Look for a supplement that uses effective quantities of such proven ingredients as caffeine, green tea extract, and synephrine. Check for accreditations, independent testing, and professional recommendations. And select supplements from established providers who place a high priority on transparency and quality assurance.
Zierer, J., Jackson, M.A., Kastenmüller, G.et al. The fecal metabolome as a functional readout of the gut microbiome. Nat Genet 50, 790–795 (2018). https://doi.org/10.1038/s41588-018-0135-7
Hursel R, Viechtbauer W, Dulloo AG, Tremblay A, Tappy L, Rumpler W, Westerterp-Plantenga MS. The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: a meta-analysis. Obes Rev. 2011 Jul;12(7):e573-81. doi: 10.1111/j.1467-789X.2011.00862.x. Epub 2011 Mar 2. PMID: 21366839.
Harpaz E, Tamir S, Weinstein A, Weinstein Y. The effect of caffeine on energy balance. J Basic Clin Physiol Pharmacol. 2017 Jan 1;28(1):1-10. doi: 10.1515/jbcpp-2016-0090. PMID: 27824614.
Jurgens TM, Whelan AM, Killian L, Doucette S, Kirk S, Foy E. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev. 2012 Dec 12;12(12):CD008650. doi: 10.1002/14651858.CD008650.pub2. PMID: 23235664; PMCID: PMC8406948.
Hursel R, Viechtbauer W, Westerterp-Plantenga MS. The effects of green tea on weight loss and weight maintenance: a meta-analysis. Int J Obes (Lond). 2009 Sep;33(9):956-61. doi: 10.1038/ijo.2009.135. Epub 2009 Jul 14. PMID: 19597519.
Kwak J, Shin D. Association between Green Tea Consumption and Abdominal Obesity Risk in Middle-Aged Korean Population: Findings from the Korean Genome and Epidemiology Study. Int J Environ Res Public Health. 2022 Feb 26;19(5):2735. doi: 10.3390/ijerph19052735. PMID: 35270427; PMCID: PMC8910422.
Whiting S, Derbyshire E, Tiwari BK. Capsaicinoids and capsinoids. A potential role for weight management? A systematic review of the evidence. Appetite. 2012 Oct;59(2):341-8. doi: 10.1016/j.appet.2012.05.015. Epub 2012 May 22. PMID: 22634197.
Janssens PL, Hursel R, Martens EA, Westerterp-Plantenga MS. Acute effects of capsaicin on energy expenditure and fat oxidation in negative energy balance. PLoS One. 2013 Jul 2;8(7):e67786. doi: 10.1371/journal.pone.0067786. PMID: 23844093; PMCID: PMC3699483.
Snitker S, Fujishima Y, Shen H, Ott S, Pi-Sunyer X, Furuhata Y, Sato H, Takahashi M. Effects of novel capsinoid treatment on fatness and energy metabolism in humans: possible pharmacogenetic implications. Am J Clin Nutr. 2009 Jan;89(1):45-50. doi: 10.3945/ajcn.2008.26561. Epub 2008 Dec 3. PMID: 19056576; PMCID: PMC3151435.
Onakpoya I, Hung SK, Perry R, Wider B, Ernst E. The Use of Garcinia Extract (Hydroxycitric Acid) as a Weight loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials. J Obes. 2011;2011:509038. doi: 10.1155/2011/509038. Epub 2010 Dec 14. PMID: 21197150; PMCID: PMC3010674.
Stohs SJ. Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p-Synephrine. Phytother Res. 2017 Oct;31(10):1463-1474. doi: 10.1002/ptr.5879. Epub 2017 Jul 28. PMID: 28752649; PMCID: PMC5655712.
Stohs SJ, Preuss HG, Shara M. A review of the human clinical studies involving Citrus aurantium (bitter orange) extract and its primary protoalkaloid p-synephrine. Int J Med Sci. 2012;9(7):527-38. doi: 10.7150/ijms.4446. Epub 2012 Aug 29. PMID: 22991491; PMCID: PMC3444973.
Stohs SJ, Preuss HG, Keith SC, Keith PL, Miller H, Kaats GR. Effects of p-synephrine alone and in combination with selected bioflavonoids on resting metabolism, blood pressure, heart rate and self-reported mood changes. Int J Med Sci. 2011 Apr 28;8(4):295-301. doi: 10.7150/ijms.8.295. PMID: 21537493; PMCID: PMC3085176.
Alkhatib A, Seijo M, Larumbe E, Naclerio F. Acute effectiveness of a "fat-loss" product on substrate utilization, perception of hunger, mood state and rate of perceived exertion at rest and during exercise. J Int Soc Sports Nutr. 2015 Nov 25;12:44. doi: 10.1186/s12970-015-0105-8. PMID: 26612980; PMCID: PMC4660661.
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