Research — Vitalis

We show our work.

Every formula, threshold, screener, and reference dataset in the four Vitalis apps traces back to a peer-reviewed paper or an authoritative body — never a "vibes-based" health score. Below is the working bibliography we maintain alongside the codebase.

30+

Peer-reviewed citations

Validated mental-health screeners

Authoritative bodies cited

Made-up health scores

The most-cited foundations.

Twelve of the thirty-plus references that show up most often in the apps — the ones that power the screens you'll use every day. Tap any to read the full citation. The complete bibliography is in the "Full bibliography" section further down.

Vitalis Core

PHQ-9 — Depression screener

9-item screening instrument with 88 %/88 % sensitivity & specificity at cutoff ≥ 10. Powers Core's mental-wellness screener, with built-in safety surfacing on item 9.

Kroenke K, Spitzer RL, Williams JB. J Gen Intern Med. 2001;16(9):606–613.

Vitalis Core

GAD-7 — Anxiety screener

7-item anxiety scale. Sensitivity 89 %, specificity 82 % at ≥ 10. Used in Core's Mental Wellness tab and tracked over time.

Spitzer RL, Kroenke K, Williams JB, Löwe B. Arch Intern Med. 2006;166(10):1092–1097.

Vitalis Core

HRV percentile benchmarks

Age-decade × sex p25 / p50 / p75 RMSSD thresholds drive Core's "Poor / Fair / Good / Excellent" HRV tier label and percentile copy. Dataset of n=84,772.

Tegegne BS, et al. Lifelines Cohort Study, 2020.

Vitalis Motion

Tanaka HRmax formula

Age-predicted maximum heart rate (208 − 0.7 × age). Default HRmax for zone calculation when no user-tested max is provided.

Tanaka H, Monahan KD, Seals DR. J Am Coll Cardiol. 2001;37(1):153–156.

Vitalis Motion

Compendium METs — calorie estimation

MET tables for 16 workout types × 4 intensities. Powers MET-based calorie estimation. Used preferentially for resistance training (see Vezina).

Ainsworth BE, Haskell WL, Herrmann SD, et al. Med Sci Sports Exerc. 2011;43(8):1575–1581.

Vitalis Motion

Keytel HR-based calorie regression

Sex-specific kJ/min regression from heart rate, weight, and age. Used for steady-state cardio where HR is a valid proxy. The engine's preferred path when HR + sex + age are all known.

Keytel LR, Goedecke JH, Noakes TD, et al. J Sports Sci. 2005;23(3):289–297.

Vitalis Motion

Why HR fails for strength training

Heart-rate methods overestimate resistance-training calories by 25–50 % vs. measured VO₂. Drives Motion's hard rule: never use HR for strength workouts.

Vezina JW, Der Ananian CA, Greer K, et al. J Strength Cond Res. 2014;28(4):1026–1031.

Vitalis Somna

Sleep Restriction Therapy

Foundational CBT-I protocol that consolidates sleep by restricting time in bed. Powers Somna's weekly maintain / expand / restrict titration engine.

Spielman AJ, Saskin P, Thorpy MJ. Sleep. 1987;10(1):45–56.

Vitalis Somna

Consensus Sleep Diary

Standardized prospective sleep self-monitoring instrument. Defines Somna's diary fields: SOL, WASO, EMA, TIB, SE %.

Carney CE, Buysse DJ, Ancoli-Israel S, et al. Sleep. 2012;35(2):287–302.

Vitalis Nourish

Mifflin–St Jeor — BMR equation

Most-accurate predictive equation for resting energy expenditure in healthy adults. Drives Nourish's calorie target.

Mifflin MD, St Jeor ST, Hill LA, et al. Am J Clin Nutr. 1990;51(2):241–247.

Vitalis Nourish

IOM AMDR — Macro distribution

Acceptable Macronutrient Distribution Ranges: protein 10–35 %, carbs 45–65 %, fat 20–35 % of energy. Default macro splits in Nourish.

Institute of Medicine. Dietary Reference Intakes. National Academies Press, 2005.

Vitalis Nourish

USDA FoodData Central

Authoritative U.S. food-composition database. Source of every calorie and macro value in Nourish's food library (SR Legacy + Foundation + Branded).

U.S. Department of Agriculture. FoodData Central, 2024.

Who we trust.

When a formula is not from a single paper, we cite an authoritative body. The list is short on purpose — we lean on organisations whose recommendations are peer-reviewed, transparently funded, and slow to change.

American Heart Association (AHA)

Cardiovascular-risk longevity claim · Core

Centers for Disease Control (CDC)

NHANES anthropometric population data · Motion

European Food Safety Authority (EFSA)

Water Adequate Intake · Nourish

Institute of Medicine (IOM) / National Academies

DRIs and AMDRs · Nourish & Core

NIH Office of Dietary Supplements

Micronutrient reference values · Core

SAMHSA / 988 Lifeline

Crisis-resource referrals · Core

U.S. Department of Agriculture (USDA)

FoodData Central nutrient values · Nourish

Full bibliography.

Every citation referenced anywhere in the codebase, grouped by app. Updated whenever a new clinical reference is added to a Vitalis app — the page below is generated from the same master bibliography we maintain in the engineering Notion workspace.

Full bibliography 30+ entries

Vitalis Core — Vitals, mental health, cycle, cardiovascular

PHQ-9 — Patient Health Questionnaire (depression)

Kroenke K, Spitzer RL, Williams JB. The PHQ-9: validity of a brief depression severity measure. J Gen Intern Med. 2001;16(9):606–613.

9-item depression screener. Sensitivity 88 %, specificity 88 % at cutoff ≥ 10. Item 9 triggers Core's crisis-resource surfacing.

GAD-7 — Generalized Anxiety Disorder scale

Spitzer RL, Kroenke K, Williams JB, Löwe B. A brief measure for assessing generalized anxiety disorder. Arch Intern Med. 2006;166(10):1092–1097.

7-item anxiety screener. Sensitivity 89 %, specificity 82 % at cutoff ≥ 10.

DASS-21 — Depression, Anxiety, Stress Scales (21-item)

Lovibond SH, Lovibond PF. Manual for the Depression Anxiety Stress Scales (2nd ed.). Sydney: Psychology Foundation; 1995.

Three 7-item subscales (Depression, Anxiety, Stress) scored on a 0–3 Likert. Subscores ×2 to be comparable to the full 42-item DASS.

MEQ-5 — Morningness-Eveningness Questionnaire

Adan A, Almirall H. Horne & Östberg morningness-eveningness questionnaire: a reduced scale. Personality and Individual Differences. 1991;12(3):241–253.

5-item chronotype classifier. Used in Core's chronotype assessment to personalize sleep + activity scheduling.

HRV percentile benchmarks (RMSSD)

Tegegne BS, et al. Reference values of heart rate variability from 10-second resting electrocardiograms: the Lifelines Cohort Study (n=84,772). 2020 systematic-review meta-analysis.

Age-decade × biological-sex p25 / p50 / p75 RMSSD thresholds power Core's HRV tier label, percentile copy, and typical-range string.

Cardiac Autonomic Neuropathy cutoffs

Common clinical-cardiology references. RMSSD < 24.94 ms and SDNN < 17.13 ms used as CAN-risk flags.

Surfaces a research-grade caution on the HRV detail card when readings fall under threshold.

AHA 2025–2026 Heart Disease & Stroke Statistics

American Heart Association. 2025–2026 Heart Disease and Stroke Statistics. Circulation, 2025.

Backs the longevity framing for modifiable cardiovascular-risk factors (BMI, BP, cholesterol, smoking, diabetes).

Menstrual-cycle metabolite research

Nature Scientific Reports — menstrual-cycle effects on > 200 metabolites; NIH/PMC menstrual-cycle research corpus.

Framing of why cycle stage matters for HDL, cholesterol, neurotransmitters, and metabolism in Core's Cycle tab.

988 Suicide & Crisis Lifeline + findahelpline.com

SAMHSA / 988 Lifeline (US); FindAHelpline.com directory (international).

Crisis-resource card triggered at moderate-or-above screener scores or any non-zero PHQ-9 item 9.

Vitalis Motion — Heart rate, calorie estimation, anthropometrics

Tanaka HRmax

Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001;37(1):153–156.

Formula: HRmax = 208 − 0.7 × age. Default HRmax when no user-tested max is set. Fallback of 190 bpm applies when age is also unknown.

Karvonen — Heart-Rate-Reserve zones

Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Ann Med Exp Biol Fenn. 1957;35(3):307–315.

Optional HRR-based zone classification (vs. %HRmax) when resting HR is available.

Compendium of Physical Activities — MET tables

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.

All MET-based calorie estimation in the engine. Full MET tables encoded for 16 WorkoutType × 4 IntensityLevel combos.

Keytel HR-based calorie regression

Keytel LR, Goedecke JH, Noakes TD, et al. Prediction of energy expenditure from heart rate monitoring during submaximal exercise. J Sports Sci. 2005;23(3):289–297.

Sex-specific kJ/min regression. Used for steady-state cardio when HR + biological sex + age are all known.

Vezina — HR is unreliable for resistance training

Vezina JW, Der Ananian CA, Greer K, et al. An examination of the differences between two methods of estimating energy expenditure in resistance training activities. J Strength Cond Res. 2014;28(4):1026–1031.

HR-based methods overestimate strength-training kcal by 25–50 %. Drives the engine rule: never use HR for strength workouts.

CDC NHANES — Population-median bodyweight

Centers for Disease Control and Prevention. NHANES 2017–18 Anthropometric Reference Data for Children and Adults. National Center for Health Statistics, 2021.

80 kg fallback weight when UserProfile.weightKg is nil. Engine warns the user to set weight in Settings to sharpen the estimate.

Vitalis Somna — CBT-I protocols, sleep diary standards

Sleep Restriction Therapy (SRT)

Spielman AJ, Saskin P, Thorpy MJ. Treatment of chronic insomnia by restriction of time in bed. Sleep. 1987;10(1):45–56.

Weekly Maintain / Expand / Restrict titration engine based on rolling 7-day Sleep Efficiency. 5.5-hour minimum-TIB floor enforced.

Consensus Sleep Diary (CSD)

Carney CE, Buysse DJ, Ancoli-Israel S, et al. The Consensus Sleep Diary: standardizing prospective sleep self-monitoring. Sleep. 2012;35(2):287–302.

Defines the clinical sleep-metric vocabulary used throughout Somna: SE %, SOL, WASO, EMA, TIB.

Imagery Rehearsal Therapy (IRT)

Krakow B, Hollifield M, Johnston L, et al. Imagery rehearsal therapy for chronic nightmares in sexual assault survivors with PTSD: a randomized controlled trial. JAMA. 2001;286(5):537–545.

Dream-rescripting fields on the sleep diary (dreamDistress, isNightmare, rescriptedDream).

Stimulus Control Therapy (SCT)

Bootzin RR. Stimulus control treatment for insomnia. Proc Am Psychol Assoc. 1972;7:395–396.

Behavioral guidance content reinforcing the bed-sleep association. Referenced in the educational module.

Vitalis Nourish — BMR, macros, hydration, nutrient database

Mifflin–St Jeor — BMR equation

Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.

Drives Nourish's calorie target. Considered the most accurate predictive equation for healthy adults.

IOM Dietary Reference Intakes — Macros (AMDR)

Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Washington, DC: National Academies Press; 2005.

Default macro-target splits in Nourish's goal builder. Protein 10–35 %, carbs 45–65 %, fat 20–35 % of total energy.

Holliday–Segar + EFSA — Hydration

Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823–832. · EFSA Panel on Dietetic Products. Scientific Opinion on Dietary Reference Values for water. EFSA Journal. 2010;8(3):1459.

35 ml/kg bodyweight default + EFSA Adequate Intake (~2.0 L women, ~2.5 L men) reference.

USDA FoodData Central

U.S. Department of Agriculture. FoodData Central, 2024. fdc.nal.usda.gov.

Calorie and macronutrient values for every food in Nourish's library (Standard Reference Legacy + Foundation Foods + Branded subset).

NIH Office of Dietary Supplements — DRIs

National Institutes of Health, Office of Dietary Supplements. Dietary Reference Intakes (DRI). ods.od.nih.gov.

Source of all micronutrient AI/RDA reference values surfaced in Core's nutrient-deficiency analysis.

How we keep this honest.

Every formula or screener added to a Vitalis app passes through a four-step protocol: (1) the citation lands here first; (2) the citation string is added to the corresponding per-app disclaimer code; (3) the disclaimer surface is attached to the UI screen where the output is consumed; (4) a unit test is written for the formula with at least one published-value sanity check.

The bibliography is maintained alongside the codebase, not as an after-the-fact marketing artifact. If you find a citation that's out of date or missing, email feedback@vitalisapp.com and we'll fix it within a week.