TDEE Research Library
The studies behind our calculators and guides, each summarised in plain English: what the researchers did, what they found and where we use it. 46 key papers and reports, grouped by topic.
A summary can’t carry every detail, so each entry links to the original paper. Where a study is small or only covers one group of people, we say so. For how we choose and check sources, see sources and fact-checking; for how the numbers are used in our tools, see our methodology.
On this page
Resting metabolism equations
Harris-Benedict equation (1918)
Measured the resting energy of 239 healthy adults in Boston and produced the first widely used prediction equations. Still in use more than a century later, but built on young, mostly lean people.
Harris JA, Benedict FG. A biometric study of human basal metabolism. Proc Natl Acad Sci USA. 1918;4(12):370-373. Read the source
Used in: Harris-Benedict Equation
Harris-Benedict revised (1984)
Re-analysed the original data with modern statistics and produced the updated coefficients most calculators now use for Harris-Benedict.
Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168-182. Read the source
Used in: Harris-Benedict Equation
Lean body mass predicts BMR best (1980)
Showed that lean body mass on its own explained resting metabolism better than weight, age or sex, and proposed BMR = 500 + 22 × lean mass.
Cunningham JJ. A reanalysis of the factors influencing basal metabolic rate in normal adults. Am J Clin Nutr. 1980;33(11):2372-2374. Read the source
Used in: Katch-McArdle Formula
Mifflin-St Jeor equation (1990)
Measured 498 healthy men and women, including people with obesity, and derived a simpler equation from weight, height, age and sex. It became the default in most modern calculators.
Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. Read the source
Used in: Mifflin-St Jeor Equation
Which equation is most accurate? (2005)
A systematic review for the American Dietetic Association compared the common equations against measured resting energy. Mifflin-St Jeor predicted within 10% of the measured value for more people, with and without obesity, than the others.
Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc. 2005;105(5):775-789. Read the source
Used in: TDEE Formula Comparison
Equations for athletes (2014)
Tested equations in recreational athletes aged 18 to 35. The lean-mass Cunningham equation performed well in this group, supporting its use for active, muscular people.
ten Haaf T, Weijs PJM. Resting energy expenditure prediction in recreational athletes of 18-35 years: confirmation of Cunningham equation and an improved weight-based alternative. PLoS One. 2014;9(10):e108460. Read the source
Activity and daily energy
Human energy requirements (2004)
The joint FAO/WHO/UNU expert report on how much energy people need. It describes lifestyles by physical activity level (total energy ÷ BMR): about 1.40 to 1.69 for sedentary or light, 1.70 to 1.99 for active and 2.00 to 2.40 for vigorous lifestyles.
FAO, WHO, UNU. Human energy requirements: report of a joint FAO/WHO/UNU expert consultation. FAO Food and Nutrition Technical Report Series 1. Rome: FAO; 2004. Read the source
Used in: TDEE Activity Levels
Everyday movement and fat gain (1999)
Sixteen adults were overfed by 1,000 kcal a day for eight weeks. Fat gain varied about tenfold, and the people who gained least were those whose everyday, non-exercise movement rose most.
Levine JA, Eberhardt NL, Jensen MD. Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science. 1999;283(5399):212-214. Read the source
Used in: How to Increase Your TDEE
Non-exercise activity thermogenesis (NEAT) (2002)
A review of the energy we spend on everything that isn’t sleeping, eating or sport. NEAT can differ by up to about 2,000 kcal a day between people of similar size, largely through work and lifestyle.
Levine JA. Non-exercise activity thermogenesis (NEAT). Best Pract Res Clin Endocrinol Metab. 2002;16(4):679-702. Read the source
Used in: Sedentary TDEE
Energy use across the life course (2021)
Pooled doubly labelled water measurements from more than 6,000 people aged eight days to 95 years. Adjusted for body size and composition, energy use was stable from about 20 to 60 and declined after 60.
Pontzer H, Yamada Y, Sagayama H, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808-812. Read the source
Used in: TDEE Calculator for Women Over 40
Measuring physical activity (2013)
Explains how physical activity and its energy cost are measured, including doubly labelled water, and what drives differences between people.
Westerterp KR. Physical activity and physical activity induced energy expenditure in humans: measurement, determinants, and effects. Front Physiol. 2013;4:90. Read the source
Used in: TDEE Activity Multiplier
The energy cost of activities (2024)
The Compendium of Physical Activities lists MET values, multiples of resting energy, for hundreds of activities. Our steps calculator uses its walking values.
Herrmann SD, Willis EA, Ainsworth BE, et al. 2024 Adult Compendium of Physical Activities: a third update of the energy costs of human activities. J Sport Health Sci. 2024;13(1):6-12. Read the source
Used in: Steps to calories calculator
Diet-induced thermogenesis (2004)
Reviewed the energy used to digest and store food: about 10% of intake on a mixed diet, with protein costing more to process than carbohydrate or fat.
Westerterp KR. Diet induced thermogenesis. Nutr Metab (Lond). 2004;1(1):5. Read the source
Used in: What Is TDEE?
Energy balance and weight change
The 3,500-calorie rule (1958)
Estimated the energy in a pound of body weight lost or gained, giving the famous 3,500 kcal per pound (about 7,700 kcal per kilo) rule of thumb.
Wishnofsky M. Caloric equivalents of gained or lost weight. Am J Clin Nutr. 1958;6(5):542-546. Read the source
Used in: 500 Calorie Deficit
The energy behind each kilo lost (2008)
Showed that the energy content of weight lost changes during a diet. Early loss includes more water and glycogen, so the 3,500-calorie rule overestimates how fast weight comes off over time.
Hall KD. What is the required energy deficit per unit weight loss? Int J Obes (Lond). 2008;32(3):573-576. Read the source
Energy imbalance and body weight (2011)
Modelled how body weight responds to a sustained change in intake. Weight changes slowly and levels off rather than falling in a straight line, with about half the change reached in roughly a year.
Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826-837. Read the source
Used in: Weight Loss Plateau
Why “one pound a week” doesn’t last (2013)
A commentary explaining why a fixed 500 kcal daily deficit doesn’t produce a steady pound a week: as weight falls, so does energy expenditure.
Thomas DM, Martin CK, Lettieri S, et al. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Commentary on a commonly accepted rule. Int J Obes (Lond). 2013;37(12):1611-1613. Read the source
Glycogen and water (1992)
Described how stored carbohydrate (glycogen) holds water, explaining the quick drop in weight at the start of a diet and the quick rise when carbohydrates return.
Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. Am J Clin Nutr. 1992;56(1 Suppl):292S-293S. Read the source
Low-fat or low-carb? (DIETFITS) (2018)
609 adults followed a healthy low-fat or a healthy low-carbohydrate diet for 12 months. Weight loss was similar on both, and neither genotype nor insulin secretion predicted who did better.
Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults: the DIETFITS randomized clinical trial. JAMA. 2018;319(7):667-679. Read the source
Dieting and metabolic adaptation
Adaptive thermogenesis (2010)
Reviewed evidence that after weight loss, people burn somewhat less energy than their new body size predicts, partly through lower resting energy and partly through more efficient muscle work.
Rosenbaum M, Leibel RL. Adaptive thermogenesis in humans. Int J Obes (Lond). 2010;34(Suppl 1):S47-S55. Read the source
Metabolism six years after “The Biggest Loser” (2016)
Followed 14 contestants six years after extreme weight loss. Their resting metabolism remained about 500 kcal a day lower than expected for their size, an extreme case that shows adaptation can persist after very aggressive dieting.
Fothergill E, Guo J, Howard L, et al. Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity (Silver Spring). 2016;24(8):1612-1619. Read the source
Used in: Is Your Calorie Deficit Too Large?
Diet breaks (MATADOR) (2018)
Men with obesity dieted for 16 weeks, either continuously or in two-week blocks separated by two weeks at maintenance. The group with breaks lost more weight and fat and kept more of it off six months later.
Byrne NM, Sainsbury A, King NA, Hills AP, Wood RE. Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. Int J Obes (Lond). 2018;42(2):129-138. Read the source
Used in: Weight Loss Plateau
Relative energy deficiency in sport (REDs) (2023)
The International Olympic Committee’s consensus on what happens when athletes eat too little for their training, including effects on hormones, bones, periods and performance.
Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee’s consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073-1097. Read the source
Used in: Is Your Calorie Deficit Too Large?
Protein, muscle and rates of change
How much protein for muscle? (2018)
A meta-analysis of 49 trials of protein with resistance training. Extra protein improved gains in muscle, and the benefit levelled off at about 1.6 g per kg of body weight a day, with some people benefiting up to about 2.2 g.
Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. Read the source
Used in: Protein calculator
High protein in a large deficit (2016)
Young men ate 40% below their needs and trained hard six days a week for four weeks. Those on 2.4 g/kg of protein gained lean mass and lost more fat than those on 1.2 g/kg.
Longland TM, Oikawa SY, Mitchell CJ, Devries MC, Phillips SM. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr. 2016;103(3):738-746. Read the source
Used in: Cutting calorie calculator
Protein for lean athletes in a deficit (2014)
A systematic review suggesting that lean, trained people in a calorie deficit may need 2.3 to 3.1 g of protein per kg of lean mass to protect muscle.
Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127-138. Read the source
Used in: TDEE Calculator for Cutting
Slow versus fast weight loss in athletes (2011)
Elite athletes losing about 0.7% of body weight a week gained lean mass and strength; those losing about 1.4% a week did not gain lean mass.
Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97-104. Read the source
Used in: Is Your Calorie Deficit Too Large?
Nutrition for natural bodybuilding (2014)
Evidence-based recommendations for contest preparation, including losing about 0.5 to 1% of body weight a week and keeping protein high.
Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. Read the source
Off-season (bulking) nutrition (2019)
Recommended a surplus of roughly 10 to 20% for novice and intermediate lifters aiming to gain 0.25 to 0.5% of body weight a week, a smaller surplus for advanced lifters, and 1.6 to 2.2 g/kg of protein.
Iraki J, Fitschen P, Espinar S, Helms E. Nutrition recommendations for bodybuilders in the off-season: a narrative review. Sports (Basel). 2019;7(7):154. Read the source
Used in: Bulking calorie calculator
Is a surplus needed for muscle growth? (2019)
Reviewed whether eating above maintenance is required to build muscle. A surplus probably helps, particularly in trained people, but the ideal size is unknown and large surpluses mainly add fat.
Slater GJ, Dieter BP, Marsh DJ, et al. Is an energy surplus required to maximize skeletal muscle hypertrophy associated with resistance training? Front Nutr. 2019;6:131. Read the source
Used in: TDEE Calculator for Muscle Gain
Training volume and muscle growth (2017)
A meta-analysis finding that 10 or more hard sets per muscle group a week produced more muscle growth than fewer than five.
Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis. J Sports Sci. 2017;35(11):1073-1082. Read the source
Used in: Lean bulk calculator
Cardio and muscle growth (2022)
An updated meta-analysis found that combining aerobic and strength training did not reduce gains in muscle size or maximal strength. Gains in explosive strength were slightly smaller, mainly when both were done in the same session.
Schumann M, Feuerbacher JF, Sünkeler M, et al. Compatibility of concurrent aerobic and strength training for skeletal muscle size and function: an updated systematic review and meta-analysis. Sports Med. 2022;52:601-612. Read the source
Used in: Lean Bulk Calorie Calculator Guide
Body recomposition (2020)
Reviewed studies showing that trained lifters, not only beginners or people with more body fat, can build muscle and lose fat at the same time with progressive resistance training and good nutrition.
Barakat C, Pearson J, Escalante G, et al. Body recomposition: can trained individuals build muscle and lose fat at the same time? Strength Cond J. 2020;42(5):7-21. Read the source
Tracking, wearables and steps
How accurately people report food (1992)
People who described themselves as unable to lose weight on low intakes underreported what they ate by 47% and overreported their exercise by 51%, measured against doubly labelled water.
Lichtman SW, Pisarska K, Berman ER, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med. 1992;327(27):1893-1898. Read the source
Used in: TDEE Not Losing Weight
Smartwatch calorie accuracy (2017)
Sixty volunteers wore seven wrist devices. Heart rate was measured well, but energy estimates were not: the best device had a median error of about 27% and the worst about 93%.
Shcherbina A, Mattsson CM, Waggott D, et al. Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort. J Pers Med. 2017;7(2):3. Read the source
Used in: Smartwatch Calorie Accuracy
Step counting on phones and wearables (2015)
On a treadmill, smartphone apps counted steps within about 7% of the true number, while some wearables undercounted by up to about 23%.
Case MA, Burwick HA, Volpp KG, Patel MS. Accuracy of smartphone applications and wearable devices for tracking physical activity data. JAMA. 2015;313(6):625-626. Read the source
Used in: Steps to calories calculator
How many steps are enough? (2004)
Proposed the step bands still used today: under 5,000 a day sedentary, 5,000 to 7,499 low active, 7,500 to 9,999 somewhat active, 10,000 or more active, and over 12,500 highly active.
Tudor-Locke C, Bassett DR Jr. How many steps/day are enough? Preliminary pedometer indices for public health. Sports Med. 2004;34(1):1-8. Read the source
Used in: Activity level calculator
Daily steps and long life (2022)
Combined 15 studies of 47,471 adults. More steps meant lower risk of death, levelling off at about 6,000 to 8,000 steps a day for adults over 60 and 8,000 to 10,000 for younger adults.
Paluch AE, Bajpai S, Bassett DR, et al. Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. Lancet Public Health. 2022;7(3):e219-e228. Read the source
Used in: How to Increase Your TDEE
Self-monitoring and weight loss (2011)
Reviewed 22 studies of people recording their diet, exercise or weight. More consistent self-monitoring went with more weight loss, although the authors noted methodological weaknesses in many of the studies.
Burke LE, Wang J, Sevick MA. Self-monitoring in weight loss: a systematic review of the literature. J Am Diet Assoc. 2011;111(1):92-102. Read the source
How long food logging takes (2019)
Among 142 adults in an online weight-loss programme, the most successful spent about 23 minutes a day logging food in the first month and under 15 minutes by the sixth. How often people logged mattered more than how long it took.
Harvey J, Krukowski R, Priest J, West D. Log often, lose more: electronic dietary self-monitoring for weight loss. Obesity (Silver Spring). 2019;27(3):380-384. Read the source
How accurate are calorie labels? (2010)
Measured the energy in reduced-calorie foods. Restaurant meals contained on average 18% more calories than stated, and frozen supermarket meals 8% more.
Urban LE, Dallal GE, Robinson LM, et al. The accuracy of stated energy contents of reduced-energy, commercially prepared foods. J Am Diet Assoc. 2010;110(1):116-123. Read the source
Women, teenagers and health conditions
The menstrual cycle and resting metabolism (2020)
Pooled 26 studies of 318 women. Resting metabolism was slightly higher in the luteal phase than in the follicular phase. The effect was small, and in studies published since 2000 it was smaller and not statistically clear.
Benton MJ, Hutchins AM, Dawes JJ. Effect of menstrual cycle on resting metabolism: a systematic review and meta-analysis. PLoS One. 2020;15(7):e0236025. Read the source
Used in: TDEE Calculator for Women
Body composition through menopause (SWAN) (2019)
Followed women through the menopause transition. At its start the rate of fat gain doubled and lean mass began to fall, with both levelling off about two years after the final period. Weight itself rose steadily, without a jump at the transition.
Greendale GA, Sternfeld B, Huang M, et al. Changes in body composition and weight during the menopause transition. JCI Insight. 2019;4(5):e124865. Read the source
Used in: TDEE Calculator for Women Over 40
Energy use across the menopausal transition (2008)
Followed 156 premenopausal women for four years. Those who became postmenopausal gained visceral fat, their energy use during sleep fell more, and the fat they burned for fuel dropped by about a third.
Lovejoy JC, Champagne CM, de Jonge L, Xie H, Smith SR. Increased visceral fat and decreased energy expenditure during the menopausal transition. Int J Obes (Lond). 2008;32(6):949-958. Read the source
Used in: TDEE Calculator for Women Over 40
Preventing obesity and eating disorders in teenagers (2016)
The American Academy of Pediatrics advises against dieting, skipping meals and diet pills for teenagers, and encourages family meals, a positive body image and talking about health rather than weight.
Golden NH, Schneider M, Wood C; Committee on Nutrition, Committee on Adolescence, Section on Obesity. Preventing obesity and eating disorders in adolescents. Pediatrics. 2016;138(3):e20161649. Read the source
Used in: TDEE Calculator for Teenagers
International PCOS guideline (2023)
Found no evidence that any one diet composition is better than another for PCOS, recommends a tailored energy deficit when weight loss is a goal, sets activity targets, and asks clinicians to consider disordered eating regardless of weight.
Teede HJ, Tay CT, Laven J, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Hum Reprod. 2023;38(9):1655-1679. Read the source
Used in: TDEE With PCOS and Thyroid Issues
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