The science

Where your numbers come from.

Your AI makes the plans and sets the targets. When it wants a reference number, it asks Memory.fit's calculators, and these are the 43 sources they are built on: position stands from the people who write the guidelines, trials and reviews. Every one is listed, so you can read it yourself.

Prior, not fence

These are a starting point, not a rulebook. Population research is the best estimate for an athlete we don't know yet; once your own data says something different, your data wins. If you thrive on more carbs per hour than the research suggests, you are not doing it wrong — the average simply stopped describing you.

The calculators

What your AI can check its numbers against.

Energy & weight

Your daily burn from training load, how a weight goal becomes a deficit, and the energy-availability floor of about 30 kcal per kg of fat-free mass.

6 sources

Fueling during sessions

Carbs per hour that climb with duration more than effort, mixed sugars for higher intakes, and training the gut to take them.

13 sources

Hydration & sweat

Fluid and sodium per hour from your own sweat tests, and a plan that never asks you to drink more than you sweat.

4 sources

Protein & recovery

A daily protein target spread across the day, and what to eat before and after a session.

5 sources

Sleep & HRV

What a short night or a falling HRV changes, read against your own baseline rather than someone else's.

9 sources

Safety guardrails

The few lines the calculators hold: they flag a target under the energy-availability floor, never plan fluid beyond your sweat rate and never suggest more than 6 mg of caffeine per kg. While you are pregnant or breastfeeding, Memory.fit refuses any calorie target below maintenance.

15 sources

Bibliography

43 sources, by topic.

Last reviewed 21 July 2026

Your daily calories

How your baseline burn and training load become a calorie target.

3 sources

  1. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  2. 2024 Adult Compendium of Physical Activities: A third update of the energy costs of human activities

    Herrmann SD, Willis EA, Ainsworth BE, et al · Journal of Sport and Health Science 13(1):6-12.

    Reference dataset · 2024 · doi:10.1016/j.jshs.2023.10.010

  3. Caloric equivalents of gained or lost weight

    Wishnofsky M · The American Journal of Clinical Nutrition 6(5):542-546.

    Study · 1958 · doi:10.1093/ajcn/6.5.542

Losing or gaining weight

How a body-composition goal is turned into a deficit, and when that deficit steps aside.

3 sources

  1. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  2. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs)

    Mountjoy M, Ackerman KE, Bailey DM, et al · British Journal of Sports Medicine 57(17):1073-1097.

    Consensus statement · 2023 · doi:10.1136/bjsports-2023-106994

  3. Does Relative Energy Deficiency in Sport (REDs) Syndrome Exist?

    Jeukendrup AE, Areta JL, Van Genechten L, et al · Sports Medicine 54(11):2793-2816.

    Review · 2024 · doi:10.1007/s40279-024-02108-y

Carbohydrate for the day

Why your daily carb number moves with how much you train.

2 sources

  1. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  2. New Horizons in Carbohydrate Research and Application for Endurance Athletes

    Podlogar T, Wallis GA · Sports Medicine 52(Suppl 1):5-23.

    Review · 2022 · doi:10.1007/s40279-022-01757-1

Fueling during a session

Carbs per hour, and why the number climbs with duration rather than effort.

10 sources

  1. A Step Towards Personalized Sports Nutrition: Carbohydrate Intake During Exercise

    Jeukendrup A · Sports Medicine 44(Suppl 1):25-33.

    Review · 2014 · doi:10.1007/s40279-014-0148-z

  2. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  3. Nutrition for Endurance Sports: Marathon, Triathlon, and Road Cycling

    Jeukendrup A · Journal of Sports Sciences 29(Suppl 1):S91-S99.

    Review · 2011 · doi:10.1080/02640414.2011.610348

  4. Carbohydrate and exercise performance: the role of multiple transportable carbohydrates

    Jeukendrup AE · Current Opinion in Clinical Nutrition and Metabolic Care 13(4):452-457.

    Review · 2010 · doi:10.1097/MCO.0b013e328339de9f

  5. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners

    Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro A, Seco-Calvo J, Urdampilleta A · Nutrients 12(5):1367.

    Randomized trial · 2020 · doi:10.3390/nu12051367

  6. Superior Endurance Performance with Ingestion of Multiple Transportable Carbohydrates

    Currell K, Jeukendrup AE · Medicine & Science in Sports & Exercise 40(2):275-281.

    Randomized trial · 2008 · doi:10.1249/mss.0b013e31815adf19

  7. New Horizons in Carbohydrate Research and Application for Endurance Athletes

    Podlogar T, Wallis GA · Sports Medicine 52(Suppl 1):5-23.

    Review · 2022 · doi:10.1007/s40279-022-01757-1

  8. Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance

    Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, Gibson P · Applied Physiology, Nutrition, and Metabolism 42(5):547-557.

    Study · 2017 · doi:10.1139/apnm-2016-0453

  9. Training the Gut for Athletes

    Jeukendrup AE · Sports Medicine 47(Suppl 1):101-110.

    Review · 2017 · doi:10.1007/s40279-017-0690-6

  10. Gastrointestinal Complaints During Exercise: Prevalence, Etiology, and Nutritional Recommendations

    de Oliveira EP, Burini RC, Jeukendrup A · Sports Medicine 44(Suppl 1):79-85.

    Review · 2014 · doi:10.1007/s40279-014-0153-2

Fluid and sodium

What to drink during sessions — and the one place we refuse to be talked upward.

4 sources

  1. National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active

    McDermott BP, Anderson SA, Armstrong LE, et al · Journal of Athletic Training 52(9):877-895.

    Position stand · 2017 · doi:10.4085/1062-6050-52.9.02

  2. American College of Sports Medicine Position Stand: Exercise and Fluid Replacement

    Sawka MN, Burke LM, Eichner ER, et al · Medicine & Science in Sports & Exercise 39(2):377-390.

    Position stand · 2007 · doi:10.1249/mss.0b013e31802ca597

  3. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability

    Baker LB · Sports Medicine 47(Suppl 1):111-128.

    Review · 2017 · doi:10.1007/s40279-017-0691-5

  4. Statement of the 3rd International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015

    Hew-Butler T, Rosner MH, Fowkes-Godek S, et al · Clinical Journal of Sport Medicine 25(4):303-320.

    Consensus statement · 2015 · doi:10.1097/JSM.0000000000000221

Protein

The daily target, and why it is spread evenly across the day rather than stacked on dinner.

4 sources

  1. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  2. International Society of Sports Nutrition Position Stand: Protein and Exercise

    Jäger R, Kerksick CM, Campbell BI, et al · Journal of the International Society of Sports Nutrition 14:20.

    Position stand · 2017 · doi:10.1186/s12970-017-0177-8

  3. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis

    Areta JL, Burke LM, Ross ML, et al · Journal of Physiology 591(9):2319-2331.

    Randomized trial · 2013 · doi:10.1113/jphysiol.2012.244897

  4. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein

    Macnaughton LS, Wardle SL, Witard OC, et al · Physiological Reports 4(15):e12893.

    Randomized trial · 2016 · doi:10.14814/phy2.12893

Before and after training

Pre-session fuel, recovery carbs and protein, and how urgent the window really is.

3 sources

  1. International Society of Sports Nutrition Position Stand: Nutrient Timing

    Kerksick CM, Arent S, Schoenfeld BJ, et al · Journal of the International Society of Sports Nutrition 14:33.

    Position stand · 2017 · doi:10.1186/s12970-017-0189-4

  2. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  3. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein

    Macnaughton LS, Wardle SL, Witard OC, et al · Physiological Reports 4(15):e12893.

    Randomized trial · 2016 · doi:10.14814/phy2.12893

Fat

Why fat is what's left once carbohydrate and protein are set.

1 source

  1. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

Sleep and recovery

What a rough night changes about your fueling — and what it deliberately doesn't.

9 sources

  1. Intermittent-sprint performance and muscle glycogen after 30 h of sleep deprivation

    Skein M, Duffield R, Edge J, Short MJ, Mündel T · Medicine & Science in Sports & Exercise.

    Study · 2011 · doi:10.1249/MSS.0b013e31820abc5a

  2. Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite

    Spiegel K, Tasali E, Penev P, Van Cauter E · Annals of Internal Medicine 141(11):846-850.

    Study · 2004 · doi:10.7326/0003-4819-141-11-200412070-00008

  3. Insufficient sleep undermines dietary efforts to reduce adiposity

    Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD · Annals of Internal Medicine 153(7).

    Randomized trial · 2010 · doi:10.7326/0003-4819-153-7-201010050-00006

  4. Training Adaptation and Heart Rate Variability in Elite Endurance Athletes: Opening the Door to Effective Monitoring

    Plews DJ, Laursen PB, Stanley J, Kilding AE, Buchheit M · Sports Medicine 43(9):773-781.

    Review · 2013 · doi:10.1007/s40279-013-0071-8

  5. Monitoring training status with HR measures: do all roads lead to Rome?

    Buchheit M · Frontiers in Physiology 5:73.

    Review · 2014 · doi:10.3389/fphys.2014.00073

  6. Evaluating Training Adaptation With Heart-Rate Measures: A Methodological Comparison

    Plews DJ, Laursen PB, Kilding AE, Buchheit M · International Journal of Sports Physiology and Performance 8(6):688-691.

    Study · 2013 · doi:10.1123/ijspp.8.6.688

  7. Sleep and the athlete: narrative review and 2021 expert consensus recommendations

    Walsh NP, Halson SL, Sargent C, et al · British Journal of Sports Medicine 55(7):356-368.

    Consensus statement · 2021 · doi:10.1136/bjsports-2020-102025

  8. Nutritional Support for Exercise-Induced Injuries

    Tipton KD · Sports Medicine 45(Suppl 1):S93-S104.

    Review · 2015 · doi:10.1007/s40279-015-0398-4

  9. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

Female physiology

Where the evidence is female-specific, where it is honestly thin, and why no deficit is stored in pregnancy.

8 sources

  1. Recommendations and Nutritional Considerations for Female Athletes: Health and Performance

    Holtzman B, Ackerman KE · Sports Medicine 51(Suppl 1):43-57.

    Review · 2021 · doi:10.1007/s40279-021-01508-8

  2. Impact of Nutrition-Based Interventions on Athletic Performance during Menstrual Cycle Phases: A Review

    Helm MM, McGinnis GR, Basu A · International Journal of Environmental Research and Public Health 18(12):6294.

    Review · 2021 · doi:10.3390/ijerph18126294

  3. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs)

    Mountjoy M, Ackerman KE, Bailey DM, et al · British Journal of Sports Medicine 57(17):1073-1097.

    Consensus statement · 2023 · doi:10.1136/bjsports-2023-106994

  4. Dietary Reference Intakes for Energy

    National Academies of Sciences, Engineering, and Medicine · Washington, DC: The National Academies Press.

    Consensus statement · 2023 · doi:10.17226/26818

  5. Weight Gain During Pregnancy: Reexamining the Guidelines

    Institute of Medicine and National Research Council; Rasmussen KM, Yaktine AL, eds · Washington, DC: The National Academies Press.

    Consensus statement · 2009 · doi:10.17226/12584

  6. Physical Activity and Exercise During Pregnancy and the Postpartum Period: ACOG Committee Opinion No. 804

    American College of Obstetricians and Gynecologists · Obstetrics & Gynecology 135(4):e178-e188.

    Position stand · 2020 · doi:10.1097/AOG.0000000000003772

  7. Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 1 — exercise in women planning pregnancy and those who are pregnant

    Bø K, Artal R, Barakat R, Brown W, et al · British Journal of Sports Medicine 50(10):571-589.

    Consensus statement · 2016 · doi:10.1136/bjsports-2016-096218

  8. Exercise and pregnancy in recreational and elite athletes: 2016/17 evidence summary from the IOC Expert Group Meeting, Lausanne. Part 3 — exercise in the postpartum period

    Bø K, Artal R, Barakat R, Brown WJ, et al · British Journal of Sports Medicine 51(21):1516-1525.

    Consensus statement · 2017 · doi:10.1136/bjsports-2017-097964

Caffeine

Doses that help, variation between people, and the ceiling we won't advise past.

1 source

  1. International Society of Sports Nutrition position stand: caffeine and exercise performance

    Guest NS, VanDusseldorp TA, Nelson MT, et al · Journal of the International Society of Sports Nutrition 18(1):1.

    Position stand · 2021 · doi:10.1186/s12970-020-00383-4

Sport-specific

Where swimming and strength work depart from the general endurance picture.

3 sources

  1. Nutrition for Swimming

    Shaw G, Boyd KT, Burke LM, Koivisto A · International Journal of Sport Nutrition and Exercise Metabolism 24(4):360-372.

    Review · 2014 · doi:10.1123/ijsnem.2014-0015

  2. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance

    Thomas DT, Erdman KA, Burke LM · Medicine & Science in Sports & Exercise 48(3):543-568.

    Position stand · 2016 · doi:10.1249/MSS.0000000000000852

  3. Nutrition Considerations for Open-Water Swimming

    Shaw G, Koivisto A, Gerrard D, Burke LM · International Journal of Sport Nutrition and Exercise Metabolism 24(4):373-381.

    Review · 2014 · doi:10.1123/ijsnem.2014-0018

Also cited

Work that contests, qualifies or predates the guidance above. We keep it visible rather than citing only what agrees with us.

3 sources

  1. Performance effects of periodized carbohydrate restriction in endurance trained athletes — a systematic review and meta-analysis

    Gejl KD, Nybo L · Journal of the International Society of Sports Nutrition 18:37.

    Meta-analysis · 2021 · doi:10.1186/s12970-021-00435-3

  2. What is the required energy deficit per unit weight loss?

    Hall KD · International Journal of Obesity 32(3):573-576.

    Study · 2008 · doi:10.1038/sj.ijo.0803720

  3. National Athletic Trainers' Association Position Statement: Fluid Replacement for Athletes

    Casa DJ, Armstrong LE, Hillman SK, et al · Journal of Athletic Training 35(2):212-224.

    Position stand · 2000

    Superseded by newer guidance; kept for the record.

The same list is in the Memory.fit app under Settings › Help › Sources. Memory.fit is not medical advice; talk to a doctor or dietitian about medical conditions. See also what to ask your AI.

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