Where the numbers and suggestions come from
Wellby calculates your target and suggests meals using equations and public databases. They are all listed here, with links for you to review them.
What this is not. Wellby does not replace an assessment by a doctor, dietitian or exercise professional. If you have a health condition, confirm these numbers with an appropriate professional before following them.
Wellby targets, projections and suggestions are estimates based on population averages. They do not know your medical history, tests or medication.
Resting energy expenditure above BMI 25
Your daily calorie target starts from this equation when your weight is above the healthy range for your height. If you did not provide sex, we use the average of the male and female versions.
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. «A new predictive equation for resting energy expenditure in healthy individuals». The American Journal of Clinical Nutrition, 1990; 51(2): 241–247.
Resting energy expenditure below BMI 25
When your weight is within or below the healthy range, the target starts from this equation, which is more accurate in that range. If you did not provide sex, we use the average of the male and female versions.
Roza AM, Shizgal HM. «The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass». The American Journal of Clinical Nutrition, 1984; 40(1): 168–182.
Weight ranges for height
The notices Wellby shows about your rate of weight loss use the World Health Organization classification.
World Health Organization. “Obesity and overweight”, fact sheet.
Food calories and nutrients
The values for each food in the catalogue — calories, protein, carbohydrates and fat — come from this public database maintained by the United States Department of Agriculture.
USDA FoodData Central. Public domain.
Calories burned during workouts
The estimate for each activity uses the metabolic equivalent (MET) published in this compendium, multiplied by the minutes you recorded.
Ainsworth BE, Haskell WL, Herrmann SD, et al. «2011 Compendium of Physical Activities: a second update of codes and MET values». Medicine & Science in Sports & Exercise, 2011; 43(8): 1575–1581.
Intermittent fasting
The fasting durations offered by Wellby — from 12 to 18 hours, including the well-known 16:8 schedule — follow time-restricted eating protocols described in this review of the health effects of fasting.
de Cabo R, Mattson MP. «Effects of Intermittent Fasting on Health, Aging, and Disease». The New England Journal of Medicine, 2019; 381(26): 2541–2551.
Who should avoid fasting
The warning shown before you begin a fast — pregnancy and breastfeeding, insulin-treated diabetes, a history of eating disorders and being under age — follows the precautions described in this clinical review.
Varady KA, Cienfuegos S, Ezpeleta M, Gabel K. «Clinical application of intermittent fasting for weight loss: progress and future directions». Nature Reviews Endocrinology, 2022; 18(5): 309–321.
Weekly physical activity
Suggestions for weekly activity — for example, 150 to 300 minutes of moderate aerobic activity and strength training on two or more days — follow World Health Organization guidelines.
Bull FC, Al-Ansari SS, Biddle S, et al. «World Health Organization 2020 guidelines on physical activity and sedentary behaviour». British Journal of Sports Medicine, 2020; 54(24): 1451–1462.
Strength, cardio and flexibility training
Wellby’s general workout guidance — frequency, intensity and progression for cardio, strength and flexibility — follows the official position of the American College of Sports Medicine.
Garber CE, Blissmer B, Deschenes MR, et al. «Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults». Medicine & Science in Sports & Exercise, 2011; 43(7): 1334–1359.
Resistance-training progression
Suggestions for increasing load, sets and repetitions over time follow this American College of Sports Medicine position for healthy adults.
American College of Sports Medicine. «Progression models in resistance training for healthy adults». Medicine & Science in Sports & Exercise, 2009; 41(3): 687–708.
Protein for muscle gain
When Wellby suggests an amount of protein for muscle gain — around 1.6 to 2.0 grams per kilogram of body weight per day together with strength training — it is based on this systematic review. This is a general reference; anyone with kidney disease should follow medical advice.
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». British Journal of Sports Medicine, 2018; 52(6): 376–384.
Daily water intake
The water target is a simple estimate — 35 ml per kilogram of body weight, between 500 ml and 8 litres — and serves as a starting point. EFSA sets reference values for total water intake of 2.0 litres per day for women and 2.5 litres for men, including water from food. Anyone with kidney or heart disease should follow medical advice.
EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). «Scientific Opinion on Dietary Reference Values for water». EFSA Journal, 2010; 8(3): 1459.