Gym Log

Calorie, TDEE and macro calculator.

Estimate your daily calorie needs (TDEE) and calculate protein, fat, and carbohydrate targets based on your body, activity level, and goal.

For generally healthy adults

This educational planning tool is not medical advice. It is not intended for people under 18, pregnancy or breastfeeding, diagnosed metabolic, kidney, liver, endocrine, or eating disorders, medical nutrition therapy, or anyone needing a measured resting metabolic rate or individual clinical advice.

1

Resting energy

Choose a published equation and enter its required measurements.

Units
Resting-energy method

Used by the resting-energy and protein calculations.

Required for Mifflin–St Jeor.

Adults 18–120. Mifflin’s source sample was aged 19–78.

Sex
2

Estimated maintenance energy

Choose a sourced lifestyle range, then adjust the PAL value if needed.

Physical activity category

Activities of daily living with little strenuous leisure activity. Published PAL range: 1.40–1.69.

Editable from 1.40–2.40. Category midpoints are Gym Log interface defaults within FAO ranges, not FAO prescriptions.

3

Daily calorie adjustment

Apply explicit arithmetic to estimated maintenance. Preset names do not promise a weight-change rate.

Adjustment preset
4

Macronutrient allocation

Set protein and fat. Carbohydrate makes up the rest of your daily calorie target.

Allowed: 0.8–3.1. Evidence-oriented training band: 1.4–2.0 g/kg/day for most healthy exercising adults.

Allowed: 10–50%. The adult AMDR is 20–35% of energy; values outside it remain available with a note.

Higher protein intakes of 2.3–3.1 g/kg/day have been discussed for resistance-trained people during energy restriction. This context applies to healthy exercising adults and is not an automatic recommendation or medical guidance.

Static worked example

A 30-year-old man at 80 kg and 180 cm has a Mifflin–St Jeor estimated REE of 1,780 kcal/day. At PAL 1.60, estimated maintenance is 2,848 kcal/day. A custom −300 kcal adjustment gives a 2,548 kcal/day target.

Protein and fat

Protein at 1.6 g/kg gives 128 g and 512 kcal. Fat at 25% gives 637 kcal and 70.78 g.

Remaining carbohydrate

2,548 − 512 − 637 leaves 1,399 kcal, or 349.75 g carbohydrate.

Equations and methodology

Peer-reviewed derivation equation

Mifflin–St Jeor estimated REE

Male REE = 10w + 6.25h − 5a + 5
Female REE = 10w + 6.25h − 5a − 161

The study measured resting energy expenditure by indirect calorimetry in 498 healthy adults: 247 women and 251 men, aged 19–78, including 264 normal-weight and 234 obese participants. The result is predicted REE, not measured BMR.

Mifflin et al. (1990).1

Historical data reanalysis

Cunningham estimated BMR

Lean body mass = weight × (1 − body fat % ÷ 100)
Estimated BMR = 500 + 22 × lean body mass

Cunningham reanalysed data for 223 subjects from Harris and Benedict’s 1919 studies; this was not a new modern athlete cohort. An estimated body-fat input compounds two estimation errors. This equation is not labelled “Katch–McArdle”.

Cunningham (1980).2

Intergovernmental expert report

Physical activity level

Estimated maintenance = predicted resting energy × PAL

FAO/WHO/UNU defines PAL as TEE ÷ BMR. Applying PAL to predicted resting energy is a practical approximation; neither component is measured. Sustainable adult ranges are 1.40–1.69, 1.70–1.99, and 2.00–2.40.

FAO/WHO/UNU (2004).3

Position stand and systematic review

Protein allocation

Protein grams = weight × g/kg/day
Protein calories = protein grams × 4

The 1.6 g/kg/day default is a general evidence-oriented starting point, not an optimum for every person. The ISSN position stand reports 1.4–2.0 g/kg/day as sufficient for most healthy exercising adults.

Jäger et al. (2017); Morton et al. (2018).4

National Academies report

Fat allocation

Fat calories = target × fat % ÷ 100
Fat grams = fat calories ÷ 9

The adult AMDR of 20–35% of energy is visible as population guidance, not an individual prescription. The calculator allows informed custom values from 10–50% with a warning outside the AMDR.

National Academies (2024).5

Intergovernmental expert report

Carbohydrate remainder and Atwater factors

Carbohydrate calories = target − protein calories − fat calories
Carbohydrate grams = carbohydrate calories ÷ 4

The general Atwater factors are protein 4, fat 9, and carbohydrate 4 kcal/g. Real foods can differ slightly; these factors support transparent allocation, not precise food calorimetry.

FAO (2003).6

Why this is an estimate

Resting-energy equations predict from population data. PAL is also selected rather than measured. Multiplying the two is useful for forming a starting hypothesis, but it is not the same as indirect calorimetry or measured total energy expenditure.

Compare the estimate with consistent body-weight trends over several weeks. Day-to-day scale changes reflect water, glycogen, food mass, and other factors, so adjust from longer observations rather than a single reading.

Why the calculator does not predict exact weight change

The historical static energy-equivalent rule is not implemented as a forecast. Body weight responds dynamically as energy expenditure, body composition, and appetite change, so fixed arithmetic overstates long-term predictability.

Wishnofsky’s 1958 paper is cited for the history of the static rule, not to predict weekly loss or gain. Hall and colleagues modelled dynamic responses to energy imbalance. For a research-based dynamic model, use the NIH/NIDDK Body Weight Planner.

Sources

  1. Peer-reviewed derivation equationMifflin, M. D., St Jeor, S. T., Hill, L. A., Scott, B. J., Daugherty, S. A., & Koh, Y. O. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 51(2), 241–247. DOI PubMed
  2. Historical data reanalysisCunningham, J. J. (1980). A reanalysis of the factors influencing basal metabolic rate in normal adults. American Journal of Clinical Nutrition, 33(11), 2372–2374. DOI PubMed
  3. Intergovernmental expert reportFAO/WHO/UNU. (2004). Human Energy Requirements: Report of a Joint FAO/WHO/UNU Expert Consultation. FAO Food and Nutrition Technical Report Series 1. Report Adult PAL table
  4. Position standJäger, R., Kerksick, C. M., Campbell, B. I., et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. JISSN, 14, 20. DOI PubMed Full text
    Systematic review / meta-analysisMorton, R. W., Murphy, K. T., McKellar, S. R., et al. (2018). A systematic review, meta-analysis and meta-regression of protein supplementation and resistance training outcomes. British Journal of Sports Medicine, 52(6), 376–384. DOI PubMed
  5. National Academies reportNational Academies of Sciences, Engineering, and Medicine. (2024). Rethinking the Acceptable Macronutrient Distribution Range for the 21st Century: A Letter Report. National Academies Press. DOI Adult AMDR table
  6. Intergovernmental expert reportFAO. (2003). Food Energy – Methods of Analysis and Conversion Factors. FAO Food and Nutrition Paper 77. Report Energy-conversion chapter
  7. Historical energy-equivalent paperWishnofsky, M. (1958). Caloric equivalents of gained or lost weight. American Journal of Clinical Nutrition, 6(5), 542–546. DOI PubMed
  8. Dynamic modelling researchHall, K. D., Sacks, G., Chandramohan, D., et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet, 378(9793), 826–837. DOI NIDDK research summary