Health Information Sources
Version 1.0
Effective date: 10 October 2026
Last updated 10 October 2026
Every health statement Tallmark makes is listed here, with the published source it comes from. The same list is in the app: Settings › Help & legal › Health sources, and the See the sources links on the result screen and the Coach.
A source supports the statement in the app. It does not mean the source's authors endorse Tallmark. Some sources are cited to show where the evidence does not support a common claim, such as "supplements make you taller".
Tallmark is not a medical device and does not give medical advice. See the Health & safety disclaimer (https://sites.google.com/view/tallmark/medical-disclaimer).
1. Your height estimate
Your predicted adult height is mainly worked out with the Khamis-Roche method, from your height, weight, age and your parents' heights. Source: Khamis HJ, Roche AF. Predicting adult stature without using skeletal age: the Khamis-Roche method. Pediatrics. 1994;94(4):504–507. Erratum: Pediatrics. 1995;95(3):457. Link: https://pubmed.ncbi.nlm.nih.gov/7936860/
"Taller than N% of teens your age", the percentile projection and the projected growth curve use the CDC 2000 growth charts, which also stand in for a weight you have not logged. Source: Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC Growth Charts for the United States: methods and development. Vital Health Stat 11. 2002;(246):1–190. Link: https://pubmed.ncbi.nlm.nih.gov/12043359/
The "genetic target" (stored with each estimate; not shown in the app since 2026-10-09) is the mid-parental height: the average of your parents' heights, adjusted for sex. Source: Tanner JM, Goldstein H, Whitehouse RH. Standards for children's height at ages 2–9 years allowing for height of parents. Arch Dis Child. 1970;45(244):755–762. Link: https://doi.org/10.1136/adc.45.244.755
The range around the estimate is wider while you have more growing left and narrows as you finish, sized against published prediction ranges that also shrink with age. Source: Tanner JM, Whitehouse RH, Marshall WA, Carter BS. Prediction of adult height from height, bone age, and occurrence of menarche, at ages 4 to 16 with allowance for midparent height. Arch Dis Child. 1975;50(1):14–26. Link: https://pubmed.ncbi.nlm.nih.gov/164838/
2. Measuring your height
You lose about half a centimetre of height over a day, so measure at the same time of day. Stretching does not change it for long. Source: Voss LD, Bailey BJR. Diurnal variation in stature: is stretching the answer? Arch Dis Child. 1997;77(4):319–322. Link: https://doi.org/10.1136/adc.77.4.319
You are tallest just after getting up, and much of the day's change happens in the first hour on your feet. Source: Tyrrell AR, Reilly T, Troup JDG. Circadian variation in stature and the effects of spinal loading. Spine. 1985;10(2):161–164. Link: https://pubmed.ncbi.nlm.nih.gov/4002039/
3. Puberty and growth timing
The puberty questions follow the Pubertal Development Scale, a self-report questionnaire. Source: Petersen AC, Crockett L, Richards M, Boxer A. A self-report measure of pubertal status: reliability, validity, and initial norms. J Youth Adolesc. 1988;17(2):117–133. Link: https://doi.org/10.1007/BF01537962
How far through your growth you may be is estimated from your age and height using the Moore maturity-offset equations. Source: Moore SA, McKay HA, Macdonald H, et al. Enhancing a somatic maturity prediction model. Med Sci Sports Exerc. 2015;47(8):1755–1764. Link: https://doi.org/10.1249/MSS.0000000000000588
Most adult height is already reached by the start and peak of the growth spurt. Source: Sanders JO, Qiu X, Lu X, et al. The uniform pattern of growth and skeletal maturation during the human adolescent growth spurt. Sci Rep. 2017;7:16705. Link: https://doi.org/10.1038/s41598-017-16996-w
The growth spurt comes at different ages for different people, and growing slows in the couple of years after periods begin. Source: Bordini B, Rosenfield RL. Normal pubertal development: part II: clinical aspects of puberty. Pediatr Rev. 2011;32(7):281–292. Link: https://pubmed.ncbi.nlm.nih.gov/21724902/
How much height comes after periods start varies a lot. Source: Gaete X, Ferrer-Rosende P, Pereira A, Mericq V. Post-menarcheal growth patterns in a contemporary cohort of Latino girls. Horm Res Paediatr. 2025;98(1):66–74. Link: https://pubmed.ncbi.nlm.nih.gov/38295778/
Two people the same age can be years apart in development — timing is not a ranking. Source: Miller BS, Sarafoglou K, Addo OY. Development of Tanner stage–age adjusted CDC height curves for research and clinical applications. J Endocr Soc. 2020;4(9):bvaa098. Link: https://doi.org/10.1210/jendso/bvaa098
The stages of puberty the questions are based on (girls). Source: Marshall WA, Tanner JM. Variations in pattern of pubertal changes in girls. Arch Dis Child. 1969;44(235):291–303. Link: https://doi.org/10.1136/adc.44.235.291
The stages of puberty the questions are based on (boys). Source: Marshall WA, Tanner JM. Variations in the pattern of pubertal changes in boys. Arch Dis Child. 1970;45(239):13–23. Link: https://doi.org/10.1136/adc.45.239.13
4. Sleep
Teenagers aged 13 to 18 need 8 to 10 hours of sleep a night. Source: Paruthi S, Brooks LJ, D'Ambrosio C, et al. Recommended amount of sleep for pediatric populations: a consensus statement of the American Academy of Sleep Medicine. J Clin Sleep Med. 2016;12(6):785–786. Link: https://doi.org/10.5664/jcsm.5866
Adults should sleep 7 or more hours a night, regularly. Source: Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. J Clin Sleep Med. 2015;11(6):591–592. Link: https://doi.org/10.5664/jcsm.4758
A regular bedtime helps, and phones and screens late at night keep teenagers up. Source: Owens J; Adolescent Sleep Working Group; Committee on Adolescence. Insufficient sleep in adolescents and young adults: an update on causes and consequences. Pediatrics. 2014;134(3):e921–e932. Link: https://doi.org/10.1542/peds.2014-1696
5. Movement and strength
5 to 17 year olds should average 60 minutes of moderate-to-vigorous activity a day across the week. Source: World Health Organization. WHO guidelines on physical activity and sedentary behaviour. Geneva: WHO; 2020. Link: https://www.who.int/publications/i/item/9789240015128
Sensible, supervised strength training is safe for teenagers and does not harm growth. Source: Stricker PR, Faigenbaum AD, McCambridge TM; Council on Sports Medicine and Fitness. Resistance training for children and adolescents. Pediatrics. 2020;145(6):e20201011. Link: https://doi.org/10.1542/peds.2020-1011
Jumping, running and other impact while you are still growing builds denser bones. Source: Weaver CM, Gordon CM, Janz KF, et al. The National Osteoporosis Foundation's position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations. Osteoporos Int. 2016;27(4):1281–1386. Link: https://doi.org/10.1007/s00198-015-3440-3
Whether an activity counts as moderate or vigorous comes from its MET value in the Compendium of Physical Activities. Source: Ainsworth BE, Haskell WL, Herrmann SD, et al. 2011 Compendium of Physical Activities: a second update of codes and MET values. Med Sci Sports Exerc. 2011;43(8):1575–1581. Link: https://doi.org/10.1249/MSS.0b013e31821ece12
6. Food and nutrients
Teens need roughly 34 to 56 g of protein a day, depending on age and sex. Source: Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academies Press; 2005. Link: https://doi.org/10.17226/10490
1300 mg of calcium a day for 9 to 18 year olds. Source: NIH Office of Dietary Supplements. Calcium: fact sheet for health professionals. Link: https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/
600 IU (15 µg) of vitamin D a day. Source: NIH Office of Dietary Supplements. Vitamin D: fact sheet for health professionals. Link: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
8 to 11 mg of zinc a day, depending on age and sex. Source: NIH Office of Dietary Supplements. Zinc: fact sheet for health professionals. Link: https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/
In trials, supplements have not changed how tall well-fed teenagers end up. Source: Kang K, Sotunde OF, Weiler HA. Effects of milk and milk-product consumption on growth among children and adolescents aged 6–18 years: a meta-analysis of randomized controlled trials. Adv Nutr. 2019;10(2):250–261. Link: https://doi.org/10.1093/advances/nmy081
Calcium supplements make a small difference to bone and none to height. Source: Winzenberg T, Shaw K, Fryer J, Jones G. Effects of calcium supplementation on bone density in healthy children: meta-analysis of randomised controlled trials. BMJ. 2006;333(7572):775. Link: https://doi.org/10.1136/bmj.38950.561400.55
7. What is not cited, and why
Water. Tallmark does not recommend a daily amount of water. The goal is one you choose; the default (1500 ml, six 250 ml glasses) is a round starting number, and the app says it is not a recommended intake. No claim is made, so no source is cited.
Calories. Tallmark sets no calorie target and hides calories unless you turn them on. No claim is made.
Everyday suggestions. A few tips are suggestions about comfort and habit rather than health claims — a cool, dark room for sleep, a short afternoon nap, lifting your screen to eye level, carrying a bag on both shoulders. They are offered as ideas to try, not as findings.
8. Things Tallmark says are not supported
These are cited above because the app tells you the evidence does not support them:
that posture work, hanging, stretching or "decompression" adds centimetres (Voss and Bailey 1997, Tyrrell 1985: the effect is the normal daily change, and it reverses overnight);
that milk, calcium or vitamin D supplements make well-fed teenagers taller (see the milk, calcium and supplement sources in section 6);
that strength training stunts growth (see the strength training source in section 5);
that more sleep, in a teenager who already sleeps enough, adds adult height (no study has shown it; the sleep guideline we cite is about health, not height).
9. Report a problem
If a link is broken or you think a statement is wrong, email tallmark.support@newversion.studio.