Sources & Methodology

At Gymbers, we want every recommendation we surface to be grounded in published evidence. The calculations and guidance below — body mass index, daily calorie and macronutrient targets, strength standards, and training methods — are based on peer-reviewed research, public health bodies, and recognized strength and conditioning literature. Our coaches and engineers reference these sources when designing the features inside the app.

BMI and weight assessment

Gymbers calculates body mass index (BMI) as weight in kilograms divided by the square of height in meters, and groups the result into the World Health Organization's adult classifications (underweight, healthy, overweight, obese). BMI is a population screening tool. It does not directly measure body fat and does not account for muscle mass, bone density, or body composition, so it should be interpreted alongside other health indicators.

• A healthy lifestyle — WHO recommendations: Body mass index.World Health Organization, Regional Office for Europe.
• Assessing your weight.Centers for Disease Control and Prevention.
• Physiology, Body Mass Index.Zierle-Ghosh A, Jan A. StatPearls. Treasure Island (FL): StatPearls Publishing; 2023.
• Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults.National Institutes of Health. Obes Res. 1998 Sep;6 Suppl 2:51S-209S.

Nutritional goal setting

When you set up nutrition targets, Gymbers estimates your basal metabolic rate (BMR) using the Mifflin-St Jeor equation, then multiplies BMR by an activity factor to estimate total daily energy expenditure (TDEE). Your daily calorie target is TDEE adjusted by a deficit or surplus depending on your fitness goal. Macronutrient grams are derived from your calorie target using the Atwater energy values (4 kcal per gram of protein and carbohydrate, 9 kcal per gram of fat). These outputs are estimates — your true energy needs depend on individual physiology, body composition, and activity outside training.

• A new predictive equation for resting energy expenditure in healthy individuals.Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. Am J Clin Nutr. 1990 Feb;51(2):241-7.
• Human energy requirements — Report of a Joint FAO/WHO/UNU Expert Consultation.Food and Agriculture Organization of the United Nations, Rome, 17–24 October 2001. (Activity-level multipliers for TDEE.)
• Food energy — methods of analysis and conversion factors.FAO Food and Nutrition Paper 77. Rome, 2003. (Atwater general factors: 4/4/9 kcal per gram for protein, carbohydrate, and fat.)
• Quantification of the effect of energy imbalance on bodyweight.Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Lancet. 2011 Aug 27;378(9793):826-37. (Basis for calorie deficit/surplus targets.)
• Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids.Institute of Medicine of the National Academies. National Academies Press, 2005.
• Dietary Guidelines for Americans, 2020–2025.U.S. Department of Agriculture and U.S. Department of Health and Human Services. 9th Edition.

Vitamins, minerals, and the rest of the day

A day's nutrient panel in Gymbers measures each nutrient against a reference intake rather than a target you set. Those references come from the Dietary Reference Intakes published by the National Academies — the Recommended Dietary Allowance where one has been established, and the Adequate Intake where the evidence supports only that. They vary by sex and by age, so the number you are measured against is the one for your own row, not a single population average.

Protein, carbohydrate, and fat are deliberately absent from this table. Those already have per-member targets derived from your calorie target and macro split, set well above the population floor, so the panel measures them against your numbers instead.

When we do not know your sex

Recording your sex is optional, and the reference tables have no third column. Where it is unrecorded we fall back to the FDA Daily Value — the single column written for a general adult, and the one printed on the nutrition labels you already read. The panel says which of the two it is using.

Three values that come from your calorie target

Fibre, saturated fat, and added sugar have no single daily figure that applies to everyone, because each scales with how much you eat. We derive them from your own calorie target:

• Fibre — 14 g per 1,000 kcal, the basis the Institute of Medicine used to set its Adequate Intake.
• Saturated fat — under 10% of daily energy, at 9 kcal per gram.
• Added sugar — under 10% of daily energy, at 4 kcal per gram.

Both limits are the Dietary Guidelines for Americans figures. If you have no calorie target set, we fall back to the Daily Value.

Nutrients we state but do not score

Total sugars, trans fat, cholesterol, and alcohol appear as amounts with no reference beside them. No current guideline sets a daily figure for them that we are willing to print as a target, so we state what you ate and stop there.

Why a total can be a floor

Food data is uneven. A packaged product carries whatever its label declares — usually energy, fat, carbohydrate, protein, and sodium — while a whole food from the USDA database carries a full laboratory panel. When some of a day's foods report a nutrient and others say nothing, the total counts only the ones that reported, so the true figure can only be higher. The app marks those totals with ≥.

Where nothing in the day reported a nutrient at all, we name it as untracked rather than showing zero. A missing measurement is not the same as an absence, and we will not print one as the other.

Two known basis mismatches

Our source data reports niacin as preformed niacin in milligrams, while the reference intake is set in niacin equivalents, which also count niacin the body makes from tryptophan. Folate is reported as total folate, while the reference is set in dietary folate equivalents, which weight synthetic folic acid more heavily. In both cases our percentage understates your actual intake slightly. We would rather name that than quietly round it away.

The reference values

Rendered from the same table the app calculates with, so this page cannot drift from what your device shows. Adult values are given here; the app also holds adolescent bands and applies the age adjustments noted below.

• Dietary Reference Intakes for Sodium and Potassium.National Academies of Sciences, Engineering, and Medicine. National Academies Press, 2019.
• Dietary Reference Intakes for Calcium and Vitamin D.Institute of Medicine. National Academies Press, 2011.
• Daily Value on the Nutrition and Supplement Facts Labels.U.S. Food and Drug Administration.
• FoodData Central.U.S. Department of Agriculture, Agricultural Research Service.
• Open Food Facts.A free, open database of food products, contributed and maintained by volunteers.

Strength standards and 1RM estimation

Gymbers estimates your one-rep max (1RM) from sets you log using the Epley and Brzycki repetition-based equations, and compares your strongest lifts to population standards using a Wilks-style normalization that adjusts for bodyweight, age, and gender. Estimated 1RM values become more accurate as the number of reps decreases, and strength categories (untrained, novice, intermediate, advanced, elite) are population benchmarks rather than medical assessments.

The Wilks score shown on your Strength Standards screen is the classic powerlifting total: we sum your one-rep max for the back squat, flat bench press, and conventional deadlift, then apply the gender-specific Wilks coefficient (a polynomial of your bodyweight, originally adopted by the International Powerlifting Federation in 1994). This produces a single number that lets you compare strength fairly across bodyweights — typical recreational lifters land around 200–300, while competitive lifters score 400 and above. The score is shown only once all three lifts have been tracked; until then you’ll see an em-dash, since Wilks is only meaningful on the full squat + bench + deadlift total, not on individual lifts.

• Poundage chart.Epley B. Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985. (Original publication of the Epley 1RM formula.)
• Strength testing — predicting a one-rep max from reps-to-fatigue.Brzycki M. Journal of Physical Education, Recreation & Dance. 1993;64(1):88-90.
• Prediction of one repetition maximum strength from multiple repetition maximum testing and anthropometry.Reynolds JM, Gordon TJ, Robergs RA. J Strength Cond Res. 2006 Aug;20(3):584-92.
• The Wilks Coefficient — bodyweight-normalized strength scoring.Wilks RA. Originally adopted by the International Powerlifting Federation in 1994. (Used as the basis for cross-bodyweight strength comparison.)

Workout programming and training methods

Recommendations around warm-up sets, repetitions in reserve (RIR) and rate of perceived exertion (RPE) targets, set types (warm-up, working, drop set, set to failure), and rest periods are drawn from standard strength and conditioning literature and peer-reviewed exercise science. They are general guidance — the right protocol for any individual depends on training experience, recovery, and goals.

• NSCA's Essentials of Strength Training and Conditioning, 4th edition.Haff GG, Triplett NT, editors. National Strength and Conditioning Association. Champaign, IL: Human Kinetics; 2016. (Warm-up structure, set/rep prescription, rest intervals.)
• Novel resistance training–specific rating of perceived exertion scale measuring repetitions in reserve.Zourdos MC, Klemp A, Dolan C, Quiles JM, Schau KA, Jo E, Helms E, Esgro B, Duncan S, Garcia Merino S, Blanco R. J Strength Cond Res. 2016 Jan;30(1):267-75. (Foundation for RIR/RPE scale.)
• ACSM Position Stand: Progression models in resistance training for healthy adults.American College of Sports Medicine. Med Sci Sports Exerc. 2009 Mar;41(3):687-708. (Set type and progression guidance.)
• Strength and hypertrophy adaptations between low- vs. high-load resistance training: a systematic review and meta-analysis.Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. J Strength Cond Res. 2017 Dec;31(12):3508-3523.
• RPE and velocity relationships for the back squat, bench press, and deadlift in powerlifters.Helms ER, Storey A, Cross MR, Brown SR, Lenetsky S, Ramsay HD, Dillen C, Zourdos MC. J Strength Cond Res. 2017 Feb;31(2):292-297.

Food and nutrition data

The foods you search and log come from public food composition databases published by national food authorities, from the collaborative Open Food Facts product database, and from entries Gymbers writes and maintains itself. Reference databases carry laboratory-measured values for generic and prepared foods; Open Food Facts covers packaged products by barcode. Where a database is published under a licence that requires attribution, the required statement is reproduced below.

• USDA FoodData Central (FNDDS and SR Legacy).U.S. Department of Agriculture, Agricultural Research Service. Public domain.
• Bundeslebensmittelschlüssel (BLS), Version 4.0.Max Rubner-Institut (2025): Bundeslebensmittelschlüssel (BLS), Version 4.0 — Deutsche Nährstoffdatenbank. Karlsruhe. DOI: 10.25826/Data20251217-134202-0. Licensed under CC BY 4.0.
• Table Ciqual 2025.Table Ciqual 2025 — ANSES (Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail), ciqual.anses.fr. Licence Ouverte 2.0 (Etalab).
• Composition of Foods Integrated Dataset (CoFID), 2021.Contains public sector information licensed under the Open Government Licence v3.0. McCance and Widdowson's “Composition of Foods Integrated Dataset” (CoFID), 2021, Public Health England.
• Swiss Food Composition Database.Swiss Food Composition Database, FSVO. Data © Federal Food Safety and Veterinary Office FSVO, naehrwertdaten.ch.
• Open Food Facts.Open, collaborative database of packaged food products. Product data is made available under the Open Database License (ODbL) v1.0; individual contents are available under the Database Contents License v1.0.
• Wikidata.Multilingual food names, dedicated to the public domain under CC0 1.0.
• Gymbers entries.Regional dishes, world-cuisine dishes and restaurant items written and maintained by Gymbers. Each entry records where its numbers come from: a matching reference-database food, a chain's own published nutrition, or a calculation from the recipe using reference values for each ingredient.

Recipe nutrition

Recipe calorie and macronutrient totals are computed by summing the per-100 g nutritional values of each ingredient (see Food and nutrition data) and scaling to the recipe and serving size you log. The same Atwater energy values used for your nutrition goals (see Nutritional goal setting) apply.

Updates to these sources

We revise this page as the underlying evidence evolves and as new features are added to Gymbers. If you spot a citation that needs updating or have a question about how a calculation is made, please reach out at contact@gymbers.com.