How to Calculate TDEE (Total Daily Energy Expenditure)

If you want to know how many calories you should eat to build muscle or lose fat, you’ll want to read this article.

“How many calories should I eat?”

This question is asked more often than you would believe, especially by those entering the fitness lifestyle for the first time.

The answer to that question is — it depends.

Do you want to build muscle? Do you want to lose body fat? Or, do are you satisfied with your current physique and you would like to maintain your weight where it is.

Different goals require different calorie intakes. And, to further complicate the matter every person is different. Even if two people are roughly the same age, sex, height, and weight, and they have a similar amount of lean body mass, the could still have very different calorie needs.

You see there isn’t a one size fits all solution to the common question of “how many calories should I eat?”

But, despair not, as we’re going to show you in this article how to calculate the number of calories you need for your body based on your goals.

No matter if your goal is muscle gain, fat loss, body recomposition, or performance, the information in the article can help you achieve the results you want.

And, it all starts with a little something called TDEE.

What is TDEE?

TDEE stands for Total Daily Energy Expenditure. It is the total number of calories you burn in a given day. Your TDEE is determined by four key factors:

  • Basal Metabolic Rate
  • Thermic Effect of Food
  • Non-Exercise Activity Thermogenesis
  • Thermic Effect of Activity (Exercise)

Basal Metabolic Rate (BMR)

Basal metabolic rate refers to the number of calories your body burns each day to keep you alive. BMR does not include physical activity, the process of digestion, or things like walking from one room to another.

Basically, BMR is the number of calories your body would expend in a 24 hour period if all you did was lay in bed all day long. This is the absolute bare minimum of calories it takes to ensure your survival.

Thermic Effect of Food (TEF)

When we eat food, our body must expend energy to digest the food we eat. This energy expenditure is referred to as the Thermic Effect of Food, and it involves breaking down the protein, carbohydrates, and fat you consume into the individual amino acids, sugars, and fatty acids that are then absorbed and used to by the body to carry out all of its processes including (but not limited to) building new tissue, synthesizing hormones, producing neurotransmitters, etc.

Research notes that the Thermic Effect of Food generally accounts for 10% of your total daily energy expenditure, but can be slightly higher or lower based on the exact macronutrient composition of your diet.[1]

For example, protein requires more energy to digest than carbohydrates or fat. So, if you’re eating a high protein diet, you will burn more calories, slightly, than if you were to eat the same number of calories, but with a significantly lower amount of protein.

Non-Exercise Activity Thermogenesis (NEAT)

Non-exercise Activity Thermogenesis (NEAT) constitutes the number of calories expended during daily movement that is not categorized as structured exercise. NEAT includes activities such as walking the dog, moving from one room to another, or taking the stairs to your office.

NEAT is highly variable from one person to another and can play a rather large or small role in your overall TDEE depending on how physically active your job or daily happenings are. For example, a waitress or construction worker will have a significantly greater NEAT than an office worker who sits at a desk for 8 hours of the day and spends 2 hours commuting to and from work.

Thermic Effect of Activity (TEA)

Thermic Effect of Activity is the number of calories burned as a result of exercise (i.e. steady-state cardio, resistance training, HIIT, sprints, CrossFit, etc.). Similar to NEAT, thermic effect of exercise is highly variable from one person to another or even from one day to another for the same person, as the intensity of training, length of the workout, and training frequency all impact your weekly thermic effect of activity.

Your TDEE is the sum of these four factors, so to put the above parameters into a math equation for simplicity sake, calculating TDEE looks a little something like this:

TDEE = BMR + TEF + NEAT + TEA

When you add all of these numbers together, you get an estimate of the number of calories you need on a daily basis to maintain your current weight.

Now, let’s take a look at how you can calculate your individual TDEE.

How to Calculate TDEE

Figuring out your total daily energy expenditure begins with calculating your BMR. The reason we’re starting with BMR is that it contributes the biggest portion of your TDEE.

Now, there are a lot of handy calculators readily available on the internet for calculating BMR as well as TDEE. But, the way to truly understand how those fancy calculators work is by understanding the equations powering them.

So, that’s exactly what we’re going to do.

Calculating Basal Metabolic Rate

Researchers have developed a number of models for calculating BMR, and one of the most popular ones is the Harris-Benedict Equation, which takes into account age, height, and weight.

Here’s a step-by-step guide to calculate your BMR using the Harris-Benedict Equation:

  • Women BMR = 655 + (9.6 X weight in kg) + (1.8 x height in cm) – (4.7 x age in yrs)
  • Men BMR = 66 + (13.7 X weight in kg) + (5 x height in cm) – (6.8 x age in yrs)

As an example, let’s take a 30-year-old male named John who is 6 feet tall and weighs 185 lbs.

So, John’s stats converting from imperial units to metric yields:

Age: 30

Height: 6’0” = 72 inches = 182.88cm (to convert inches to centimeters, multiply your height in inches by 2.54)

Weight: 185 lbs = 84.09kg (to convert pounds to kilograms, divide your weight in pounds by 2.2)

Using the Harris-Benedict Equation for men, and plugging the above numbers into the equation gives you:

BMR = 66 + (13.7 x 84.09) + (5 x 182.88) – (6.8 x 30)

BMR = 66 + 1152.03 + 914.4 – 204

BMR = 1928.43

So, as a bare minimum to sustain life and ensure longevity, our example male John would need to consume roughly ~1930 calories.

The next step in figuring out TDEE would be to calculate the thermic effect of food as well as the non-exercise and exercise factors. However, these calculations are extremely tedious and the equations to model the caloric expenditure each requires isn’t the most reliable.

Fortunately, you don’t have to spend hours performing more tedious calculations. You don’t even have to use a fitness monitor or rely on those erroneous “Calories Burned” readouts on cardio machines to figure out the rest of the components of your TDEE.

Researchers have determined a set of “activity multipliers, known as the Katch-McArdle multipliers.

To calculate your approximate TDEE, simply multiply these activity factors by your BMR:

  • Sedentary (little to no exercise + work a desk job) = 1.2
  • Lightly Active (light exercise 1-3 days / week) = 1.375
  • Moderately Active (moderate exercise 3-5 days / week) = 1.55
  • Very Active (heavy exercise 6-7 days / week) = 1.725
  • Extremely Active (very heavy exercise, hard labor job, training 2x / day) = 1.9

Going back to our example guy John, let’s assume he trains 3 days per week following a high-frequency full body training program with no additional steady-state cardio or HIIT training during the week. This puts John in the “Moderately Active” category.

To calculate John’s approximate TDEE, multiply his BMR by 1.55. This gives us:

TDEE = 1.55 x BMR

TDEE = 1.55 x 1928.43

TDEE = 2989.07

So, our example guy John needs to consume about 2990 calories each day just to maintain his current weight.

Now, at this point, it’s important we stress that these equations and activity multipliers provide AN ESTIMATE for your daily calorie requirements. That is, your actual TDEE could be a little higher or lower than the number you calculate when you use the formula. But, it should be fairly close, and at the very least, it gives you a rough idea of where to start when figuring out a meal plan and setting macronutrient goals.

Speaking of goals, now let’s look at how you can use your TDEE to enhance your body composition whether it be for muscle gain or fat loss.

Manipulating TDEE for Muscle Gain and Fat Loss

So, how does knowing your TDEE help you gain muscle or lose fat?

While there’s endless debate in the fitness world about the “optimal” way to go about reshaping your body, this much is true:

  • If you want to lose fat, you need to eat fewer calories than your TDEE. Doing so forces your body to draw energy from its fat stores to compensate for the calories you’re not consuming each day. Do this long enough and you will lose weight and body fat
  • If you want to gain muscle mass, you need to eat more calories than your TDEE.To gain weight, you must be in a caloric surplus. Coupled with a rigorous training program following the principles of progressive overload, those extra calories will be put to building new muscle tissue.

Now, let’s see how to put this into practice

For Fat Loss

To lose fat, we typically recommend that using a caloric deficit of 20%. Once again using John as an example, if he wanted to cut fat, his caloric intake would be:

20% of TDEE = 0.20 x 2990 = 598

Daily calorie intake for weight loss: 2990 – 598 = 2,392 calories

At a 598 daily calorie deficit, John would lose a little over 1 pound per week, as 1 pound of fat equals approximately 3500 calories.

Now that we have the caloric intake needed for fat loss, we need to set John’s macros.

Protein: 1 gram per pound of bodyweight

Fat: 0.3 – 0.5 grams per pound of bodyweight

Carbohydrates: The number of calories remaining after protein and fat requirements are met.

Going back to our example guy John his daily macros, while eating at a 20% caloric deficit, would be:

  • Protein: 1g / lb x 185 lbs = 185g (Calories = 185g x 4 calories / g of protein = 740)
  • Fat:5g / lb x 185 lbs = 92.5g (Calories = 92.5g x 9 calories / g of fat = 832.5)Note: Fat can range from 0.3-0.5 grams per pound of bodyweight. Adjust up or down based on your own dietary preferences. If you enjoy eating a higher fat diet, use the 0.5g/lb multiplier, and if you enjoy a higher carb, lower fat diet use 0.3g/lb.
  • Carbs are determined by subtracting your protein and fat calories from the daily calorie total, then dividing by 4 to get the number of carbs you eat per day (as each gram of carbohydrate contains 4 calories). Calories left after removing protein and fat Calories = 2,392 – 740 – 832.5 Calories alloted for carbohydrate = 819.5 (which we’ll round up to 820 for simplicity)Now, divide 820 by 4 to get the total grams of carbohydrates John needs to consume each day:820 / 4 = 205g Carbohydrates

Therefore, John would consume the following macronutrient profile to lose fat while preserving lean muscle mass:

Protein: 185g
Fats: 92.5g
Carbohydrates: 205g

Eating at this calorie level should have John losing a little over one pound per week. Now, remember, the TDEE and BMR calculations are estimates. If you find, after performing your own calculations, that you’re not losing weight, then remove another 100 calories from your daily calorie intake and assess progress over the next 2 weeks.

If however, you find yourself losing more than 2 pounds per week, add 100 calories back into your diet. While it might seem great, losing too much weight too fast typically results in muscle loss as well, which is not what you want in the least.

Now, let’s look at how to manipulate TDEE for gaining muscle.

Muscle Gain

Gaining weight, and preferably muscle, requires consuming more calories than your body expends on a daily basis. When combined with a structured resistance training program, a caloric surplus provides the essential nutrients needed to optimize performance and build muscle.

For the longest time, it was preached that in order to get big, you had to eat big too. But, as sports nutrition has developed over the years, lifters and researchers alike have learned that the surplus needed to build lean muscle tissue isn’t a huge as we were once led to believe.

Simply put, the body can synthesize a finite amount of muscle tissue at any given time. That means that eating substantially more than what is required to build new muscle just leads to excess fat gain. Therefore, the trick to minimizing fat gain while trying to build muscle is to use a moderate calorie surplus, giving your body just enough to grow bigger, stronger, and faster, without getting fatter. This approach to muscle gain is known today as lean bulking.

To build muscle and limit fat gain, you need to consume roughly 200-300 calories above your TDEE.

So, using our example guy John again, whose TDEE was 2990. He would need to consume between 3190-3290 calories consistently day in and day out to gain muscle.

When undertaking a mass gaining phase, most coaches recommend that you get your surplus calories from carbohydrates, as they fuel performance in training, enhance recovery, and prevent muscle breakdown. They also help raise insulin levels, which is great for shuttling nutrients into your muscles cells needed for repair and growth.

But, if you find you enjoy more fat in your diet, you can feel free to get the extra 200-300 calories from fat or any mix of protein, carbohydrates, and fat. There’s no set in stone ideal ratio for gaining muscle once your minimums are taken care of.

Now, if you find that you are not gaining at least 0.25 lb/week, add another 100 calories to the daily caloric intake. If, however, you’re gaining over 1 lb per week, reduce your calorie intake by 100-200 calories. Gaining too much weight too fast usually means that you’re gaining a good bit of fat in addition to muscle, which means you’re eventually going to have to spend more time cutting later on in your fitness journey.

Takeaway

Total daily energy expenditure is the number of calories your body burns in a given day taking everything into account from sleep to digestion to exercise. TDEE calculators offer a way for you to figure out a close approximation to the actual number of calories you burn in a day, which you can then use to structure a diet for building muscle or burning fat.

Through proper manipulation and application of your TDEE, you have the power to reshape your body in your own ideal image and never ever have to settle for another cookie cutter meal plan or diet protocol. When knowing how many calories you need to eat for muscle gain or fat loss, you can eat the foods you enjoy while adhering to the calorie and macronutrient goals you set.

The saying goes “with knowledge comes power.” Well, we’ve now given you the knowledge and power to craft your ideal physique. It’s up to you to do the rest!

References

  1. Tappy, L. (1996). Thermic effect of food and sympathetic nervous system activity in humans. Reproduction, Nutrition, Development, 36(4), 391–397. http://www.ncbi.nlm.nih.gov/pubmed/8878356/

A Close Up on the Amino Acids in Protein Powder

Protein powder is quite frequently the very first supplement (outside of a multivitamin) you purchased when starting to workout. You were told protein was important for building muscles, and you were also probably told that whey protein is one of the best proteins to take for building muscle and recovering from training.

On the surface, protein powders seem pretty simple and straightforward. They include one or more forms of powdered protein (i.e. whey, casein, egg, milk, pea, etc.) along with salt, artificial sweeteners, and one or two thickeners and stabilizers. On top of that, using them couldn’t be any simpler. Simply add water, milk, or whatever liquid you want, shake, drink, and BOOM! You’ve got your quick fix of protein to support muscle recovery and growth.

But, have you ever given any thought to what your actual protein is made of?

More specifically, the individual amino acids that make up your favorite whey protein powder?

Probably not, and there’s nothing wrong with that. That’s where this quick reference guide comes in.

Ahead, we’ll explain what each of the different amino acids that go into making a complete whey protein powder is, and how they support your athletic goals.

But first, let’s make a quick distinction…

Naturally Occurring Amino Acids vs Spiked Protein Powders

While this issue isn’t nearly as much of a problem as it was 5-10 years ago, it still exists — spiked protein powders. What we mean by “spiked” is that extra free form amino acids, such as L-Glutamine, L-Taurine, or Creatine, were added in addition to whey protein in countless mass market protein powders.

These added amino acids artificially inflated the protein count on many protein powders, meaning that you weren’t really getting as much protein as the label claimed.

How can you tell if your protein is spiked?

Take a look at the ingredients panel and if you see a bunch of free-form amino acids listed before or after the whey protein, chances are pretty good that it’s spiked.

Now, the amino acids that we’re about to discuss below are the ones naturally occurring in whey protein, they’re not separate ones added to artificially enhance the protein content. Most protein powders will list which amino acids are naturally occurring in their whey protein powder on the side of the tub, but few people rarely know what those amino acids do, outside of the BCAAs, and that brings us back to the point of this article — a close up look at the individual amino acids in your whey protein powder.

So, let’s get to it!

The Amino Acids in Whey Protein

Whole food proteins, such as whey protein, chicken, steak, etc., are made from a combination of essential amino acids (EAA), conditional amino acids (CAA) and nonessential amino acids (NAA).

Essential Amino Acids are those that the body cannot synthesize on its own and they must be obtained from the diet. Nonessential Amino Acids are those that the body can produce from other essential amino acids, carbohydrates, and fats. Conditional Amino Acids can usually be synthesized by the human body; however, under certain conditions like illness or stress the body might not be able or might be limited in the ability to synthesize them.

What about BCAAs (branched-chain amino acids)?

The three BCAAs (leucine, isoleucine, and valine) are a special subcategory of the essential amino acids, that serves as nitrogen carriers, which assist muscles in creating other amino acids required for anabolism (muscle growth).

With all of that squared away, let’s learn a little more about the amino acids in your whey protein powder:

Alanine (NAA): Not to be confused with the beta alanine, alanine is a nonessential amino acid that plays a critical role in glucose production and blood sugar regulation. Alanine also supports optimal functioning of the immune system as well as kidney stone prevention.*

Arginine (CAA): The most well-known function of arginine is to serve as the substrate for the production of nitric oxide, a powerful vasodilator that enhances blood flow and pumps during training and supports cardiovascular function. Arginine also plays a role in the healthy functioning of the pituitary gland and works with two other amino acids in L-Ornithine and phenylalanine.

Aspartic Acid (NAA): Aspartic acid serves a key role in the Krebs Cycle (TCA cycle) that provides energy to the body through its production of ATP (adenosine triphosphate). This nonessential amino acid is also needed for the production of immunoglobulins, antibodies, and DNA. In case you weren’t aware, immunoglobulins and antibodies are responsible for recognizing, binding, and eventually destroying harmful viruses and bacteria that invade the body.*

Cystine (CAA): Synthesized in the liver from the essential amino acid methionine, cysteine fulfills several important functions in the body. First and foremost, cysteine is needed for the production of glutathione, one of the most powerful antioxidants in the body. This amino acid also helps slow down the aging process, and some research indicates it may be helpful in preventing dementia and multiple sclerosis.*

Glutamic Acid (CAA): Glutamic acid belongs to the same family of amino acids as L-Glutamine, the most abundant amino acid in the body. Glutamic acid plays a key role in immune function and digestion as well as serving as an important excitatory neurotransmitter in the brain.*

Glycine (NAA): Glycine is the smallest and simplest of the 20+ amino acids found in the human body and the second most abundant found in human proteins and enzymes. Formed in the liver from serine and threonine, glycine plays an important role in the central nervous system and the digestive system and is needed for the production of many important acids including nucleic acid, bile acids, and creatine phosphate.*

Histidine (CAA): Histidine is an aromatic amino acid used to synthesize proteins and affects numerous metabolic reactions in the body. It also regulates the pH value of the blood and helps form the myelin sheath, a protective coating that surrounds all nerve cells and protects them from damage.*

Isoleucine (EAA): The “weaker” and younger brother of leucine, Isoleucine stimulates muscle protein synthesis in the body, though not quite as powerfully as leucine does. However, where isoleucine does stand out is its role in enhancing glucose uptake by skeletal muscle as well as glucose utilization during intense exercise.*

Leucine (EAA): The “king” of amino acids, leucine is most well known for being the most powerful stimulator of the mTOR pathway in the body, which drives muscle protein synthesis.

Lysine (EAA): Lysine is needed for the production of antibodies, and has been found to be beneficial for protecting against the herpes virus. Additionally, lysine is also needed for the production of carnitine – a substance that helps the body use fat for energy. This essential amino acid also aids calcium absorption and is needed for protein synthesis.*

Methionine (EAA): Methionine is vital to the production of L-Cysteine, an incredibly potent antioxidant that combats oxidative stress induced by intense training. This essential amino acid also aids the liver with the digestion of fats and serves as a “building block” for the production of carnitine, adrenaline, choline, and melatonin.*

Phenylalanine (EAA): A precursor to tyrosine, phenylalanine is important in the synthesis of the important neurotransmitters. Due to this amino acid’s role in neurotransmission, phenylalanine has been investigated as a possible treatment for depression and several other illnesses including multiple sclerosis, Parkinson’s disease, and ADD.*

Proline (CAA): Manufactured in the liver from ornithine, glutamine, and glutamate, proline is a secondary amino acid that is one of the primary amino acids used to generate collagen, the fundamental protein of skin, bones, ligaments, and tendons. This amino acid also fortifies the artery walls and protects the endothelium layer, highlighting its importance in maintaining cardiovascular health.*

Serine (NAA): Formed from glycine, serine plays a central role in the proper functioning of the central nervous system and production of antibodies. It is also required for the production of phospholipids used in cell production. To top it off, this amino acid also serves a role in the function of DNA and RNA, fat metabolism, and muscle formation.*

Threonine (EAA): A precursor to glycine and serine, threonine is essential for protein synthesis, and it also supports proper functioning of the central nervous, immune, digestive, and skeletal muscle systems of the body. Threonine is needed to produce antibodies, which bolster the immune system, and the mucus gel layer that covers the digestive tract.*

Tryptophan (EAA): Tryptophan plays a critical crucial role in lifting mood, as the uses this amino acid to generate serotonin, one of the “happy hormones”. Another important function of this essential amino acid is that it supports the synthesis of niacin, an essential B vitamin involved in energy production.

Tyrosine (CAA): Tyrosine is an incredibly important amino acid affecting mood, motivation, and reward. Moreover, tyrosine also plays a role in regulating pain sensitivity, stress, and appetite.*

Valine (EAA): The final component of the trio of BCAAs, valine is the least studied of the lot. As one of the BCAAs, valine helps drive muscle protein synthesis and is essential for glycogen synthesis in muscle tissue as well as energy conversion. On top of that, valine also has a supporting role in the proper cognitive function and immune system function.*

Takeaway

Protein is essential for building muscle, and when you’re looking for one of the best forms of protein to aid you in your fitness journey, there’s no better place to look than whey. It’s packed full of all the amino acids you need to repair, recover, and grow bigger and stronger. Next time you pick up your favorite tub of protein, see what amino acids it lists, and use this guide to help understand all of what goes into this fitness-lifestyle favorite.

References

  1. Saccà L, Trimarco B, Perez G, Rengo F. Studies on the Mechanism Underlying the Influence of Alanine Infusion on Glucose Dynamics in the Dog. Diabetes. 1977;26(4):262 LP-270. http://diabetes.diabetesjournals.org/content/26/4/262.abstract.
  2. Bode-Böger SM, Böger RH, Alfke H, et al. l-Arginine Induces Nitric Oxide–Dependent Vasodilation in Patients With Critical Limb Ischemia. Circulation. 1996;93(1):85 LP-90. http://circ.ahajournals.org/content/93/1/85.abstract.
  3. Wang H, Thomas C, Christensen E. OF ACETATE ACID AND PYRUVATE IN YEAST. J. Biol. Chem. 1952, 197:663-667.
  4. Stanislaus R, Gilg AG, Singh AK, Singh I. N-acetyl-L-cysteine ameliorates the inflammatory disease process in experimental autoimmune encephalomyelitis in Lewis rats. Journal of Autoimmune Diseases. 2005;2:4. doi:10.1186/1740-2557-2-4.
  5. Marmo, E. (1988), L‐glutamic acid as a neurotransmitter in the CNS. Med. Res. Rev., 8: 441-458. doi:10.1002/med.2610080305
  6. Nagana Gowda GA, Shanaiah N, Cooper A, Maluccio M, Raftery D. Bile Acids Conjugation in Human Bile Is Not Random: New Insights from 1H-NMR Spectroscopy at 800 MHz. Lipids. 2009;44(6):527-535. doi:10.1007/s11745-009-3296-4.
  7. Singer, M. and Salpeter, M. M. (1966), The transport of 3H‐l‐histidine through the Schwann and myelin sheath into the axon, including a reevaluation of myelin function. J. Morphol., 120: 281-315. doi:10.1002/jmor.1051200305
  8. Doi M, et al. Isoleucine, a potent plasma glucose-lowering amino acid, stimulates glucose uptake in C2C12 myotubes . Biochem Biophys Res Commun. (2003
  9. Gran P, Cameron-Smith D. The actions of exogenous leucine on mTOR signalling and amino acid transporters in human myotubes. BMC Physiology. 2011;11:10. doi:10.1186/1472-6793-11-10.
  10. Griffith RS, Walsh DE, Myrmel KH, Thompson RW, Behforooz A. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. 1987;175(4):183-190.
  11. Brosnan JT, Brosnan ME. The Sulfur-Containing Amino Acids: An Overview. J Nutr. 2006;136(6):1636S-1640.
  12. Beckmann H, Strauss MA, Ludolph E. Dl-phenylalanine in depressed patients: an open study. J Neural Transm. 1977;41(2-3):123-134.
  13. Rath M. (1992). Reducing the risk for cardiovascular disease with nutritional supplements. Journal of Orthomolecular Medicine. Volume 7, (pp. 153–162).
  14. Calderini G, Aporti F, Bonetti AC, Zanotti A, Toffano G. Serine phospholipids and aging brain. Prog Clin Biol Res. 1985;192:383-386.
  15. Feng L, Peng Y, Wu P, et al. Threonine Affects Intestinal Function, Protein Synthesis and Gene Expression of TOR in Jian Carp (Cyprinus carpio var. Jian). Merrifield D, ed. PLoS ONE. 2013;8(7):e69974. doi:10.1371/journal.pone.0069974.
  16. Jenkins TA, Nguyen JCD, Polglaze KE, Bertrand PP. Influence of Tryptophan and Serotonin on Mood and Cognition with a Possible Role of the Gut-Brain Axis. Nutrients. 2016;8(1):56. doi:10.3390/nu8010056.
  17. Deijen J and Orlebeke J. (1994). Effect of tyrosine on cognitive function and blood pressure under stress. Brain Research Bulletin. Volume 33, Issue 3, (pp. 319-23).
  18. Jellinger K et al (1978). Brain monoamines in hepatic encephalopathy and other types of metabolic coma. Journal of Neural Transmission Supplementum. Volume 14, (pp. 103-120).

The Complete Guide to Sweat

If you want to know what sweat is, why you sweat, and why sweat smells, you want to read this article.

Following a grueling weightlifting or high-intensity cardio session, there are a few noticeable things:

  • Your Muscles Ache
  • Your Lungs Burn
  • Your Shirt is Drenched in Sweat

Sweat is a sign of accomplishment, a sign of hard work, a sign of commitment. It’s also a sign of nervousness; thus, the expression, “he’s sweating bullets.”

We’ve all experienced the sensation of sweating, and had those unsightly “pit stains” at the most inopportune of moments. But, why do we sweat, what is sweat made of, and why does it stink sometimes?

Ahead, we’ll answer all of those questions and a whole lot more, as we get up close and personal with all things sweat.

Let’s start by answering a very simple question…

What is Sweat?

Sweating, a.k.a. perspiring, is the production of fluids secreted through the skin of animals. As such, sweat is an NBF — normal body function.

It’s composed mostly of water (about 99%) [5], but also contains a host of other compounds and biomarkers including:

  • Minerals (sodium, chloride, potassium)
  • Ammonia
  • Ethanol
  • Cortisol
  • Urea
  • Lactate
  • Neuropeptides
  • Cytokines

Due to this abundance of biomarkers, researchers have begun exploring the use of sweat as a means for continuous bio-monitoring as opposed to other fluids, such as saliva or urine.

While there are several types of sweat glands, sweat is primarily produced via one of two types of sweat glands [2]:

Eccrine glands

Eccrine glands cover most of your body but are found predominantly in on the forehead, palms, armpits, and soles of your feet. Sweat from eccrine glands is watery but doesn’t taste like water due to the presence of salt, protein, ammonia, and urea in it.

Sweat from eccrine glands is clear, odorless, and mostly water, but does contain many of the compounds we just detailed. It has a pH ranging from 4-6.8[6]

Here’s a closeup look at the eccrine gland [4]:

Apocrine glands

Apocrine glands are larger than eccrine glands and localized primarily in the armpits, groin, and breast area. As opposed to eccrine glands, which secrete sweat directly onto the surface of the skin, apocrine glands secrete sweat into the pilary canal of the hair follicle. Since apocrine glands secrete sweat near hair follicles, they generally smell the worst.

As such, sweat produced from these glands is most often associated with body odor.

Apocrine glands are most active during periods of stress and sexual excitement. Interestingly enough, sweat from apocrine glands contains pheromone-like compounds.

It’s also worth mentioning that these glands don’t really start functioning until puberty.

On average, an individual will have between two to four million sweat glands with an average density of 200 sweat glands per square centimeter. However, the amount of sweat you release is actually determined more by fitness level, body weight, gender, genetics, and various environmental factors.

Why Do We Sweat?

The body generates sweat for two big reasons:

  • Thermoregulation
  • As a Response to Stress

Let’s look a little bit deeper into each one of these.

Thermoregulation

Our bodies crave homeostasis or balance. This applies especially to our core body temperature. While it can tolerate a wide range of external temperatures, the internal temperature of the body has a rather limited range of temperatures it can withstand before activating its countermeasures, i.e. thermoregulatory sweat.

For instance, if core temperature is constantly above 104°F (40°C), cell death and protein denaturation can occur, eventually leading to organ failure. To combat this elevated body temperature, the body will begin sweating to remove heat from the body and help lower core body temperature. FYI, if this cooling mechanism fails (for whatever reason) it can lead to hyperthermia and death. So, when you look at it front that point of view, sweating is actually a very good, life-preserving thing!

In addition to helping cool the body off, sweat also removes waste from the body by secreting sodium salts and nitrogenous waste (such as urea) onto the skin surface.

How does this happen?

It all starts with thermosensitive neurons in the hypothalamus. These neurons regulate sweating in response to “reading” the temperature of the skin and body. Stimulation occurs via activation by acetylcholine (a powerful neurotransmitter), which binds to the eccrine glands muscarinic receptors. [7]

Other factors that can affect thermoregulatory sweating include:

  • Gender
  • Menstrual Cycle
  • Circadian Rhythm
  • Air Humidity
  • Exercise

The primary driver behind thermoregulatory sweating is the sum of internal body temperature and mean (average) skin temperature, such that sweating will commence with internal body temperature exceeds mean skin temperature by a factor of 10. [3,8]

Cooling of the body occurs via evaporation of sweat from the skin surface. This is due to the phenomenon of evaporative cooling, whereby thermal energy is released by the evaporation of water from the skin surface, leading to a reduction in skin and core temperature.

Stress

Sweat induced by stress is commonly referred to as “emotional sweating”. In addition to stress, this emotional sweating can also be brought on by pain, fear, and/or anxiety. And, while it can occur all over the body, it’s most obvious on the palms of your hands, soles of your feet and under your arms.

Researchers believe the reason emotional stress manifests itself on the palms and soles is in part due to evolution. When encountering a stressor (i.e. a wild predator), the body would secrete sweat onto the palms and soles to increase friction, thereby preventing slipping when climbing or running. [9]

In contrast to thermoregulatory sweat, emotional sweat doesn’t depend on external temperature, and as such, it will decrease during periods of relaxation and sleep.

Additionally, while thermoregulatory sweat is produced by the eccrine glands, emotional stress is secreted by the apocrine glands. It has a higher pH (6-7.5) compared to eccrine sweat, and it looks a bit different too.

While eccrine (thermoregulatory) sweat is colorless and odorless, apocrine-secreted sweat is oily, cloudy, and viscous. And, just like eccrine sweat, apocrine (stress) sweat contains a bounty of compounds including:

  • Water
  • Protein
  • Fats (lipids)
  • Carbohydrate Waste Material
  • Steroids

Gustatory

While not nearly as prevalent as the thermoregulatory and emotional sweating, there is a third type of sweating that deserves mention — gustatory sweat.

Gustatory sweat is caused by ingestion of certain foods that directly or indirectly trigger a thermal effect. First, eating food increases metabolism, leading to elevated body temperature, which can signal thermoregulatory sweating.

Second, spicy, peppery foods (cayenne, jalapeno, etc.) induce sweating of the forehead, scalp, and neck. This is due to a fiery little substance in spicy foods called capsaicin. It’s the molecule that gives chile peppers their bite and when we consume capsaicin, it binds to heat sensors in our mouth leading to a thermoregulatory response. [5]

Why Does Sweat Stink?

On its own, sweat is odorless. However, the warm, damp conditions of our armpits are the perfect breeding ground for bacteria. When we sweat, it comes into contact with this bacteria on our skin, and the hungry bacteria feast on the sweat, producing an abundance of stinky compounds, which we all know too well as body odor — B.O.

The longer the sweat and bacteria mingle, the worse the smell gets — this is the reason a dirty workout shirt smells 100x worse the next day.

Why Does Sweat Stain Shirts?

Similar to what we discussed above, sweat isn’t the actual cause of your pit stains (i.e. underarm area of shirts turning yellow). Sweat is actually colorless.

However, the yellowing of the armpit region of shirts comes as the result of a chemical reaction between your sweat and the chemicals present in your antiperspirant or clothing. For example, aluminum, the active ingredient in most antiperspirants, mixes with the salt in your sweat and leads to yellow stains.

Sweat Can Make You Happy

We all know the sense of accomplishment and satisfaction that accompanies a tough workout and have the shirt caked in sweat for proof.

But, did you know that sweat (or rather smelling someone else’s sweat) can make you happy?

Apparently, it can, according to some research conducted in 2015.

Chemosignals are chemical signals your body gives off, typically through sweat. Other people can interact or encounter these chemical signals and react to them.

Researchers found that chemosignals emitted from people in a “happy state” resulted in “facial expression and perceptual-processing style indicative of happiness in the receivers of those signals.”[10]

In other words, by being around happy people who are sweating, you can pick up on the “good vibes” and receive a boost in mood and happiness.

For a while, researchers have known that negative feelings could be transferred via chemosignals, but now, it appears you can also improve your mood by simply changing the type of people you are around — and it’s all thanks to sweat!

Takeaway

Sweat gets a bad rap for things like pit stains and body odor, but upon further inspection, sweat isn’t the bad guy — bacteria is!

Sweat is an essential bodily function that helps regulate internal core temperature. It’s triggered by a number of things including temperature, emotional stress, and even the food we eat. Sweat helps cool us off, and it might even be able to lift our mood.

And, if you’re looking to really sweat it out during your training sessions, take a serving of Steel Sweat.

Steel Sweat® is a moderately stimmed pre-workout supplement scientifically formulated to increase thermogenesis, boost metabolism, ramp up fat burning and perspiration. Take it before morning cardio or before your resistance training sessions and get ready to sweat like never before!

References

  1. Mosher HH (1933). “Simultaneous Study of Constituents of Urine and Perspiration” (PDF). The Journal of Biological Chemistry. 99 (3): 781–790.
  2. Hanukoglu I, Boggula VR, Vaknine H, Sharma S, Kleyman T, Hanukoglu A (January 2017). “Expression of epithelial sodium channel (ENaC) and CFTR in the human epidermis and epidermal appendages”. Histochemistry and Cell Biology. 147 (6): 733–748. doi:10.1007/s00418-016-1535-3
  3. Jessen, C. Temperature Regulation in Humans and Other Mammals, 193 pp. Springer-Verlag, Berlin (2001).
  4. Sonner, Z., Wilder, E., Heikenfeld, J., Kasting, G., Beyette, F., Swaile, D., … Naik, R. (2015). The microfluidics of the eccrine sweat gland, including biomarker partitioning, transport, and biosensing implications. Biomicrofluidics, 9(3). https://doi.org/10.1063/1.4921039
  5. Wilke, K., Martin, A., Terstegen, L., & Biel, S. S. (2007). A short history of sweat gland biology. International Journal of Cosmetic Science, 29(3), 169–179. https://doi.org/10.1111/j.1467-2494.2007.00387.x
  6. Draelos, Zoe Diana (2010). “Prevention of Cosmetic Problems”. In Norman, R. A. Preventive Dermatology. Springer. p. 182. doi:10.1007/978-1-84996-021-2_16
  7. Shibasaki, Manabu; Wilson, Thad E.; Crandall, Craig G. (2006). “Neural control and mechanisms of eccrine sweating during heat stress and exercise”. Journal of Applied Physiology. 100 (5): 1692–1701. doi:10.1152/japplphysiol.01124.2005. ISSN 8750-7587. PMID 16614366
  8. Johnson, J.M. and Proppe, D.W. Cardiovascular adjustments to heat stress. In: Handbook of Physiology. Section 4: Environmental Physiology (Fregly, M.J. and Blatteis, C.M. eds), pp. 215–243. Oxford University Press, Oxford (1996).
  9. Folk Jr, G. Edgar; Semken Jr, A. (1 September 1991). “The evolution of sweat glands”. International Journal of Biometeorology. 35 (3): 180–186. doi:10.1007/BF01049065. ISSN 0020-7128
  10. de Groot, J. H. B., Smeets, M. A. M., Rowson, M. J., Bulsing, P. J., Blonk, C. G., Wilkinson, J. E., & Semin, G. R. (2015). A Sniff of Happiness. Psychological Science, 26(6), 684–700. https://doi.org/10.1177/0956797614566318