You may have heard the term Thermogenesis thrown around in the gym or in your HIIT class. Personal trainers and coaches love using training terminology, like posterior chain, or the “after-burn effect”. While thermogenesis is also one of those phrases, what exactly is thermogenesis, and how does thermogenesis work? We’re going to get into the nitty gritty details, so you know the ins and outs of thermogenics and how thermogenesis and metabolism relate.

What Is Thermogenesis

The therm, I mean term thermogenesis comes from the Greek word thermos for heat. All metabolic processes produce heat as a thermodynamic inefficiency or byproduct. In general, however, thermogenesis refers to the process of heat generation, in relation to metabolism and the heat expended in direct response to the food you eat. The heat your body burns is measured in calories. The greater the thermogenic effect of your body, the high number of calories you’ll expend [R].

Seemingly, thermogenesis is simple. It’s the process of heat generation as a result of the metabolic process. But there is more than just one type of thermogenesis.

In general, there are three different classifications of thermogenesis 

• Diet Induced Thermogenesis (DIT)
• Exercise Associated Thermogenesis (EAT)
• Non-exercise activity thermogenesis (NEAT)—not including sleeping, eating, or exercise

Diet-Induced Thermogenesis

Some of the calories you eat are used to digest, absorb, metabolize, and store food, while some other calories are burned off as heat. This process is known by several different names including diet induced thermogenesis (DIT), specific dynamic action (SDA), and the thermic effect of food (TEF).

DIT or the thermic effect of food is essentially the energy “cost” it takes to breakdown your food, digest it, and turn it into fuel. While the cumulative effect of the thermic effect of food on total daily expenditure is small, it still contributes to burning more total calories and supporting your weight loss goals. 

A general estimate of the thermic effect of food is around 10% of total daily caloric intake, though the effect varies significantly with different types of foods. The energy required to digest each macronutrient or the (TEF) can be expressed as a percentage of the energy provide by each macronutrient [R].

• Fat: 9 calories per gram with a TEF of 0–3%.
• Carbohydrate: 4 calories per gram with a TEF of 5–10%.
• Protein: 4 calories per gram with a TEF of 20–30%.

Thus, if a meal contains 500kcal then the thermic effect of processing that meal is about 50kcal.

Essentially eating healthier foods, will help you burn even more calories by boosting your metabolism. Yet another reason to eat a healthy mix of lean proteins, quality carbohydrates, and healthy fats.

The thermic effect of food is one of the components of metabolism or total daily energy expenditure (TDEE). Daily energy expenditure consists of three components: basal metabolic rate which includes EAT, diet-induced thermogenesis, and the energy cost of physical activity or NEAT [R].

Basal Metabolic Rate

Often used interchangeably with resting metabolic rate, your basal metabolic rate is defined as the minimum number of calories your body burns to exist without any other outside influences. BMR is the amount of energy that is expended at rest in a neutral environment after the digestive system has been inactive for about 12 hours. It is the rate of one’s metabolism when waking in the morning after “fasting” during sleep [R].

Resting metabolic rate is defined as the energy required by your body to perform basic functions at rest. Some of these essential functions include basic brain activities, blood circulation, sleep, nutrient absorption, digestion, temperature regulation, and breathing. RMR represents the minimum amount of energy required to keep your body functioning.

BMR does not consider the variable effect of physical activity and accounts for approximately 60% of daily energy expenditure [R].

Exercise Associated Thermogenesis

The third form of thermogenesis comes from physical activity, also known as the thermic effect of physical activity (TEPA). Exercise burns more calories. Burning calories comes from the thermodynamics your body produces from the activity you engage in.

Aerobic metabolism, requires oxygen and uses either fats or carbohydrates to produce energy, required for low-intensity activity. Anaerobic metabolism converts carbohydrates to ATP when energy is required more rapidly.

TEPA includes both exercise and non-exercise activity thermogenesis (NEAT), which could include things like the energy it requires to walk your dog, take the garbage out, or carry the groceries up the stairs.

How To Increase Thermogenesis

1. Thermogenic Supplements

Thermogenics are often associated with dietary supplements, which are used and marketed for increasing thermogenesis, specifically burning more calories at rest, or enhancing the calorie-burning process, which can help you lose weight faster.

Thermogenics can support weight loss goals, and help you optimize your results when taken consistently. There are several thermogenics which have been proven to increase the production of heat and burn more calories at rest such as ginger root, green tea extract, and turmeric.

Green Tea Extract

Green tea contains catechins, and epigallocatechin gallate (EGCG) a powerful polyphenol thought to help stimulate the process of fat oxidation and lipolysis. Green tea works to mobilize fat cells by inhibiting an enzyme that breaks down the fat-burning hormone norepinephrine (noradrenaline). When this enzyme is inhibited, noradrenaline increases, thus promoting more fat to breakdown.

RELATED ARTICLE Can Green Tea Help You Lose Weight

The thermic effect of green tea also contributes to its powerful fat burning properties. Studies suggest that supplementing with green tea extract or EGCG can increase the number of calories you burn at rest 3-8% [R]. Adding in a few cups of green tea per day, and/or a thermogenic weight loss supplement that contains green tea before your workouts, will help you burn more calories and body fat. In fact, studies show that green tea extract taken pre-workout can increase your fat burning ability 17% [R].

RECOMMENDED PRODUCT Therm (50mg of Green Tea and 20 active weight loss ingredients, 90 Servings)

Turmeric

Recent evidence suggests that Turmeric may help promote weight loss. Turmeric contains compounds with anti-inflammatory and medicinal properties called curcuminoids. The most vital compound within turmeric is its active ingredient curcumin. A large body of evidence shows that in addition to curcumin, turmeric contains over one hundred unique chemical properties that contribute to its countless therapeutic and anti-inflammatory effects.

Research suggests that curcumin has protective effects against regaining weight, through the inhibition of adipose tissue growth and increasing insulin sensitivity [R].

A study evaluating the effects of curcumin on extended weight loss, administered 44 subjects who had lost at least 2% of their total body weight with 800mg of curcumin with 8mg of piperine twice per day for thirty days post diet and training. The results showed that curcumin increased weight loss, (1.88 to 4.91%), enhanced body fat reduction (from 0.70 to 8.43%), increased waistline reduction (from 2.36 to 4.14%), improved hip circumference reduction from 0.74 to 2.51% and enhanced reduction of BMI (from 2.10 to 6.43%). Although this is a preliminary study, the findings suggest that curcumin could positively influence weight management [R].

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2. Physical Activity

The thermic effect of exercise or any type of training will ultimately help you burn more calories. However, the best training mode to increase thermogenesis, is resistance training.

The more muscle mass you have, the more calories you burn at rest. Strength training will help build more muscle mass, therefore burning more calories at rest, boosting your metabolic rate, aka increasing your body’s thermic effect. Resting muscle tissue burns 6kcal/lb per day at rest, thus the more muscle you have, the more calories you burn.

Post workout your metabolism stays elevated through a process called excess post-exercise oxygen consumption (EPOC). EPOC also known as the after-burn effect, refers to the oxygen and energy (in calories) it takes for your body to repair your muscle tissue during recovery. EPOC can be a major contributor to your total daily caloric expenditure by increasing your body’s thermic effect [R]. Prolonged workouts with more intense resistance training at heavier weights have been associated with a more substantial EPOC [R]. 

3. Thermogenic Foods

Certain types of foods have a more significant effect on thermogenesis and metabolism than others. Protein for example has a thermic effect ranging between 20-30%, meaning that 20-30% of the protein you eat, is used as energy to process and metabolize. Compare that with 0-3% for fat, which has little to no effect on thermogenesis.

A mixed diet including healthy fats, lean proteins, and quality carbohydrates will result in 5-15% of total daily energy expenditure through diet induced thermogenesis. Although DIT is the smallest contributing component to daily expenditure, including thermogenic foods in your diet does play a critical role in maintaining weight and contributing to weight loss.

4. Non Exercise Activity Thermogenesis 

Non-energy exercise activity thermogenesis (NEAT) is the energy expended conducting normal day activities other than planned exercise and training, or (sleeping, eating, and breathing). NEAT includes activities such as walking, cooking, cleaning, yardwork, and involuntary movements like fidgeting.

While it may seem small, even trivial movements and activities substantially increase metabolic rate and the calorie burning process and attribute to the cumulative effect of NEAT. A cohort study published in the American Journal Of Preventative Medicine, followed 12,778 women for 12 years to investigate the effects of fidgeting and sedentary time on mortality rates. Results found that fidgeting may reduce the risk of death associated with excessive sedentary time [R]

What Is Thermogenesis: Takeaway

Simply put, by increasing thermogenesis, you are in fact increasing your metabolism and its rate, thereby helping your body burn more calories. If your goal is to maintain your weight, lose body fat, or lose a few pounds, increasing your daily energy expenditure is key. While diet and exercise is the tried and true method of reaching your health and fitness goals, including more lean protein, a proven thermogenic supplement, and lifting weights, will induce a greater thermic response and help you burn more calories.

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References

Westerterp, K.R. Diet induced thermogenesis. Nutr Metab (Lond) 1, 5 (2004). https://doi.org/10.1186/1743-7075-1-5

Himms-Hagen J. Role of thermogenesis in the regulation of energy balance in relation to obesity. Can J Physiol Pharmacol. 1989 Apr;67(4):394-401. doi: 10.1139/y89-063. PMID: 2667732.

John W. Pelley, in Elsevier's Integrated Review Biochemistry (Second Edition), 2012

Trayhurn, in Encyclopedia of Food Sciences and Nutrition (Second Edition), 2003