DFUNLIFE Intelligence

DFUNLIFE Intelligence helps you track your own eating plan and the health data in Apple Health against the targets you set. It is for general wellness. It does not diagnose, treat or prevent any condition, and it is not for medication or insulin dosing.

What I Eat: The Gap Between Looking Healthy and Being Healthy, by Devin Mack (ENQUAL LLC, 2026).

What it is. An engineer's field guide to personal metabolic tracking: the practices the author layered in over 25 years, including the Build and Clean day plan the DFUNLIFE Intelligence app follows.

What it is not. Not a medical text, not a diet book and not the work of a clinician. The author is not a physician.

Not a low-carb or zero-carb plan. The book treats carbohydrate as something to time, more on Build days and less on Clean days, not something to eliminate.

Nothing in the app or the book is medical advice, a diagnosis or a treatment. It is not for insulin or medication dosing. Check with your doctor before you begin, change or stop any diet, supplement, exercise or medication, especially if you take prescription medication or manage a health condition.

• Medical thresholds (blood pressure, blood sugar, adult BMI, adult sleep duration): from the professional bodies listed below. How the app averages and grades your readings is the app's own method, described with each entry.
• Health calculations (energy, estimated lifts, heart-rate zones, averages): some use the published methods named below; others are the app's own methods, labelled as such with their limits. Estimates are labelled as estimates.
• Your plan's targets (carb-to-protein ratio bands, fat, calories): on the book plans, the author's plan from What I Eat; if you changed a target, it is your own setting. They are not medical guidelines, and how each number was first chosen was not recorded. Research listed with them is background, not their source.

Tile 10 · Blood pressure

• Blood pressure categories: Medical threshold: Normal, Elevated, Stage 1 and Stage 2. The categories are the guideline's; the app's 7-day average is its own method (see the next entry). Jones DW, Ferdinand KC, Taler SJ, et al. 2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ASPC/NMA/PCNA/SGIM Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults. Hypertension. 2025;82(10):e212–e316. https://doi.org/10.1161/HYP.0000000000000249
• "Very high" warning: The American Heart Association calls a reading above 180/120 severe. The app warns when the top number is 180 or higher, or the bottom number is 120 or higher, to be cautious. The page also advises taking the reading again and calling emergency services if a very high reading comes with symptoms such as chest pain or shortness of breath. How long the app suggests resting before the repeat reading is the app's own advice. American Heart Association. Understanding Blood Pressure Readings. https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings
• 7-day home average: The app's own method: the mean of usable blood pressure readings in Apple Health over 7 days, with at least 4 readings. Readings come from any app or device that writes blood pressure to Apple Health; readings outside what a home cuff can measure are left out. A home average is not a diagnosis.

Tile 10 · Blood glucose

• Fasting blood sugar ranges: Medical threshold: the American Diabetes Association's fasting plasma glucose ranges (100–125 mg/dL and 126 mg/dL or above, confirmed by repeat testing). The app compares your morning readings with these ranges; that comparison is the app's own method, is not a laboratory test and cannot diagnose diabetes. American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1). https://doi.org/10.2337/dc26-S002
• Low blood sugar: Medical threshold: below 70 mg/dL is low; below 54 mg/dL is Level 2 (clinically significant) low blood sugar, and a low that needs another person's help is Level 3 at any reading. If you feel unwell or can't treat a low yourself, get urgent help. American Diabetes Association Professional Practice Committee. 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes—2026. Diabetes Care. 2026;49(Suppl 1):S132–S149. https://doi.org/10.2337/dc26-S006

Tile 10 · Trends and units

• Trend arrows and glucose units: The app's own method: a trend arrow shows a change only when it is larger than a set margin (for example 3 mmHg for blood pressure or 3 mg/dL for glucose) and enough readings exist; smaller changes show as steady. Glucose in mmol/L is converted at 18.016 mg/dL per mmol/L. Arrows describe your readings, not your health.

Tile 10 · Watch estimates

• VO2 max, breathing rate and blood oxygen: These are Apple Watch estimates: VO2 max shows the latest estimate; breathing rate and blood oxygen show overnight averages. The app doesn't grade them, and they are not medical measurements.

Tile 10 · Your targets

• Daylight and everyday-movement energy: Graded only against targets you set. Everyday-movement energy is Apple Watch active energy minus workout energy, the app's own method.

Sleep

• Adult sleep duration: Medical threshold: adults 18–60 should sleep 7 or more hours a night, regularly. Your sleep target and the dial's grades (including deep sleep) are your plan's settings, not part of this statement. 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. https://www.aasm.org/resources/pdf/adultsleepdurationconsensus.pdf
• Sleep averages: The app's own method: a 7-night average needs at least 4 nights with sleep recorded, and a monthly point at least 15. Sleep stages are Apple Watch estimates, not a sleep study.
• Deep sleep and hormones (background): Background, not a target: a small study in eight healthy young men, in which a drug was used to deepen sleep, found growth hormone release tracked deep sleep. A second small study found cortisol release was held lower during early-night deep sleep. Neither shows an effect on next-day stress. Van Cauter E, Plat L, Scharf MB, et al. J Clin Invest. 1997;100(3):745–753. https://doi.org/10.1172/JCI119587 · Bierwolf C, Struve K, Marshall L, Born J, Fehm HL. Slow wave sleep drives inhibition of pituitary-adrenal secretion in humans. J Neuroendocrinol. 1997;9:479–484. https://doi.org/10.1046/j.1365-2826.1997.00605.x
• Short sleep, hunger and blood sugar: Background: in small studies of healthy young men, a few nights of restricted sleep raised hunger and appetite, and several nights of sleep debt slowed the body's handling of glucose. These are study results, not a prediction for any one night. Spiegel K, Tasali E, Penev P, Van Cauter E. Ann Intern Med. 2004;141(11):846–850. https://doi.org/10.7326/0003-4819-141-11-200412070-00008 · Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999;354(9188):1435–1439. https://doi.org/10.1016/S0140-6736(99)01376-8

Sleep HRV

• HRV baseline and heart-rate dip: The app's own method: each night's HRV is the mean of Apple Watch readings while you sleep, compared with the average of your recent nights on the same watch (your plan's baseline window); the grade bands and the heart-rate dip floors are your plan's settings. The dip is estimated from Apple Health heart rate and is shown for information only.
• Heart rate variability: Background: HRV is the variation in time between heartbeats, and it differs widely between healthy people of the same age, which is why this app compares you only with yourself. Shaffer F, Ginsberg JP. An overview of heart rate variability metrics and norms. Front Public Health. 2017;5:258. https://doi.org/10.3389/fpubh.2017.00258

Stress

• Stress dial signals: The app's own method: the Stress dial counts how many of four signals (low sleep HRV, raised resting heart rate, low deep sleep and high active energy, a heavy training day) are off your own recent average by your plan's set percentages. It is not a mood score or a diagnosis. Background on HRV: see the Sleep HRV entry.

Steps

• Daily steps: Your steps target is set by your plan. Background: more daily steps were linked with lower risk of death, levelling off at lower counts in older adults; this is an association, not a personal target. Paluch AE, Bajpai S, Bassett DR, et al. Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. Lancet Public Health. 2022;7:e219–e228. https://pmc.ncbi.nlm.nih.gov/articles/PMC9289978/
• Everyday movement (NEAT): Background: movement outside exercise (walking, chores, standing) can account for most of the energy a person uses above rest, and varies a lot between people. Levine JA. Non-exercise activity thermogenesis (NEAT). Best Pract Res Clin Endocrinol Metab. 2002;16(4):679–702. https://doi.org/10.1053/beem.2002.0227

Water

• Water: Your water target is set by your plan. Background: the adequate intake is total water from food and drink; the app counts the drinks you log. National Academies. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (2004). https://www.nationalacademies.org/news/report-sets-dietary-intake-levels-for-water-salt-and-potassium-to-maintain-health-and-reduce-chronic-disease-risk

Weight and body fat

• Weight trend and rate: The app's own method: a 7-day average weight, needing 4 weigh-ins. The green rate of 0.25–1.0% of body weight a week is the app's own rule. For comparison, a review for lean athletes losing weight suggests about 0.5–1% a week to help keep muscle. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. https://doi.org/10.1186/1550-2783-11-20
• Body fat from a home scale: Background: home scales estimate body fat by bioelectrical impedance, which is sensitive to how much water you're carrying, so readings are best compared at the same time each day. Kyle UG, Bosaeus I, De Lorenzo AD, et al. Bioelectrical impedance analysis—part I: review of principles and methods. Clin Nutr. 2004;23(5):1226–1243. https://doi.org/10.1016/j.clnu.2004.06.004 · Part II: utilization in clinical practice. Clin Nutr. 2004;23(6):1430–1453. https://doi.org/10.1016/j.clnu.2004.09.012

Antioxidants

• Fat and antioxidant absorption: Background: adding avocado fat raised lycopene absorption from salsa; in a small study of one vitamin E preparation (alpha-tocopheryl acetate), more fat in a meal raised its absorption; lycopene from tomato paste was absorbed better than from fresh tomatoes. The amount the app suggests (1 tablespoon of oil, or about 15 g of fat in the meal) is the plan's rule, not a research threshold. Unlu NZ, Bohn T, Clinton SK, Schwartz SJ. J Nutr. 2005;135(3):431–436. https://doi.org/10.1093/jn/135.3.431 · Jeanes YM, Hall WL, Ellard S, Lee E, Lodge JK. Br J Nutr. 2004;92(4):575–579. https://doi.org/10.1079/BJN20041249 · Gärtner C, Stahl W, Sies H. Am J Clin Nutr. 1997;66(1):116–122. https://doi.org/10.1093/ajcn/66.1.116

Weight goal (BMI)

• Adult BMI categories: Medical threshold: for adults 20 and over, a BMI below 18.5 is underweight. BMI is a screening measure, not a diagnosis, and adult categories don't apply to teenagers. Centers for Disease Control and Prevention. Adult BMI Categories. https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html

Your body

• Lean mass and body-fat estimate: The app's own arithmetic: lean mass = weight × (1 − body fat ÷ 100). Without a body-fat reading in Apple Health, the range you pick is used at its midpoint (37.5% for 35%+). Both are estimates, and every target built on them carries the same uncertainty.
• Energy used: The app's own method: the mean of resting plus active energy in Apple Health over the last 30 days (with 7 to 29 days it's labelled an estimate). These are device estimates.

Energy estimate

• Energy from lean mass: Health calculation (estimate), used until Apple Health has 7 or more days with both resting and active energy: estimated resting energy = 370 + 21.6 × lean mass in kg; multiplied by an activity factor, it gives an estimate of the energy you use in a day. It is not a measurement, and individuals differ. Katch–McArdle equation: McArdle WD, Katch FI, Katch VL. Exercise Physiology: Energy, Nutrition and Human Performance. 4th ed. Baltimore: Williams & Wilkins; 1996 [page to confirm]. As stated in Branco MC, Alves FD, Zanella PB, de Souza CG. Comparison between equations for estimation of resting energy expenditure and indirect calorimetry in gymnasts. Rev Bras Nutr Esportiva. 2018;12(70):195–203. https://dialnet.unirioja.es/descarga/articulo/6379653.pdf
• Activity multipliers: The activity multipliers (1.2–1.725) are a common estimate, not a guideline. Once Apple Health has 7 or more days with both resting and active energy (from any source), the app uses their average instead, itself a device estimate (the app's rule). For comparison, the FAO/WHO/UNU physical activity levels differ from these factors. FAO/WHO/UNU. Human energy requirements. Report of a joint expert consultation (Rome, October 2001; published 2004). https://www.fao.org/3/y5686e/y5686e08.htm
• Low-energy warning: The app's own screening rule: it warns when your lowest planned intake, less your average workout energy, comes to under 35 kcal per kg of fat-free mass. That's an estimate from your plan, not a measurement of each day. The IOC statement explains that the often-quoted 45 and 30 levels came from small, short-term studies and that no single cutoff fits everyone, so a value above 30 is not a sign of safety. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073–1097. https://doi.org/10.1136/bjsports-2023-106994

Protein

• Protein per kilogram: Background. The app sets protein per kilogram of lean mass, the author's plan rule; this position stand gives ranges per kilogram of body weight (1.4–2.0 g/kg for most exercising people). Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. https://doi.org/10.1186/s12970-017-0177-8

Your plan's targets (protein)

• Your plan's protein targets: On the book plans, protein targets per kilogram of lean mass are the author's plan from What I Eat (Tables 5.1 and 5.2); if you changed them, they are your own settings. Not a medical guideline, and how each number was first chosen was not recorded. Background on protein per kilogram of body weight: see the Protein entry.

Food checks

• Food energy factors: The app's food checks are simple arithmetic using general factors: 4 kcal per gram of protein and carbohydrate, 9 for fat and 2 for fibre (the label check leaves fibre out). Labels may use other permitted methods, so a mismatch doesn't mean a label is wrong. FAO. Food energy – methods of analysis and conversion factors (2003). https://www.fao.org/4/Y5022E/y5022e05.htm · US FDA. 21 CFR 101.9. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9
• Net carbs and label formats: Net carbs in this app are total carbohydrate minus fibre, the app's own definition. US labels include fibre in Total Carbohydrate (US FDA 21 CFR 101.9. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9). EU and UK labels list carbohydrate without fibre, so fibre is not subtracted again (Regulation (EU) No 1169/2011, Annex I. https://eur-lex.europa.eu/eli/reg/2011/1169/oj). Canadian labels also include fibre in carbohydrate (Health Canada. Carbohydrates. https://www.canada.ca/en/health-canada/services/nutrients/carbohydrates.html).

Sodium and potassium

• Sodium: Background for the sodium limit: under 2,300 mg a day for people 14 and older. US HHS/USDA. Dietary Guidelines for Americans 2025–2030 (January 2026). https://cdn.realfood.gov/DGA.pdf
• Potassium: Background for the potassium amount: the adult adequate intake is 3,400 mg a day for men and 2,600 mg for women. It is not a treatment target; people with kidney disease or on some medicines need their doctor's advice. NASEM. Dietary Reference Intakes for Sodium and Potassium. 2019. https://doi.org/10.17226/25353
• Sodium relative to potassium: Background: in a review of studies, a lower ratio of sodium to potassium in urine went with lower blood pressure. It doesn't set a ratio target. Ndanuko RN, Ibrahim R, Hapsari RA, et al. Association between the urinary sodium to potassium ratio and blood pressure in adults: a systematic review and meta-analysis. Adv Nutr. 2021;12(5):1751–1767. https://doi.org/10.1093/advances/nmab036 The study measured sodium and potassium in 24-hour urine, not food logs, so it doesn't set a target for the app's food figures.

Juice notes

• Grapefruit and medicines: Grapefruit can slow CYP3A4, an enzyme that helps clear some medicines; the effect varies with the person, the medicine and the amount. If a medicine you take carries a grapefruit warning, ask your doctor or pharmacist how much grapefruit, if any, is safe. US Food and Drug Administration. Grapefruit Juice and Some Drugs Don't Mix. https://www.fda.gov/consumers/consumer-updates/grapefruit-juice-and-some-drugs-dont-mix
• Oxalate and calcium: Calcium eaten in the same meal binds oxalate in the gut, so less is absorbed. This doesn't mean a particular smoothie prevents kidney stones; if you've had stones, ask your doctor or dietitian. National Kidney Foundation. Kidney Stones Diet and Prevention. https://www.kidney.org/kidney-topics/kidney-stones-diet-and-prevention

Workouts

• Estimated best lift: Health calculation (estimate): your best single lift estimated from a set, weight × (1 + reps ÷ 30). It's an estimate, less accurate at high reps, not a measured maximum. Epley B. Poundage Chart (1985), as evaluated in LeSuer DA, McCormick JH, Mayhew JL, et al. The accuracy of prediction equations for estimating 1-RM performance in the bench press, squat, and deadlift. J Strength Cond Res. 1997;11(4):211–213. https://doi.org/10.1519/00124278-199711000-00001

Heart-rate zones (export file)

• Heart-rate zones (export file): Maximum heart rate is estimated as 208 − 0.7 × age, an average for healthy adults; individuals vary widely. Tanaka H, Monahan KD, Seals DR. J Am Coll Cardiol. 2001;37(1):153–156. https://pubmed.ncbi.nlm.nih.gov/11153730/ · Zones use the heart-rate reserve method: Karvonen MJ, Kentala E, Mustala O. Ann Med Exp Biol Fenn. 1957;35(3):307–315. https://pubmed.ncbi.nlm.nih.gov/13470504/ · If you entered your own maximum heart rate, the app uses that instead. The 50–90% banding is the app's convention.

Insights (resting heart rate, breathing rate)

• Resting heart rate and breathing rate: The rules are the app's own: resting heart rate at least your plan's set percentage above your plan's baseline average on 3 or more days in a row, and breathing rate during sleep 2 or more breaths a minute above your 30-night average on 2 or more nights in a row. A rise above your own baseline is worth noting; it can happen with illness, and it is not a diagnosis. Background, from studies of infection: Mishra T, et al. Nat Biomed Eng. 2020;4:1208–1220. https://doi.org/10.1038/s41551-020-00640-6 · Miller DJ, et al. PLoS ONE. 2020;15(12):e0243693. https://doi.org/10.1371/journal.pone.0243693

Insights (HRV and recovery)

• HRV, training load and recovery insights: The rules are the app's own: they compare your HRV, deep sleep and activity with your own averages and your plan's ranges, and say what was measured. They don't measure recovery or diagnose anything. Background on HRV: see the Sleep HRV entry.

Insights (steps)

• Walking pace: A brisk walk is about 100 steps a minute, so 20 minutes is roughly 2,000 steps. Tudor-Locke C, Aguiar EJ, Han H, et al. Walking cadence (steps/min) and intensity in 21–40 year olds: CADENCE-adults. Int J Behav Nutr Phys Act. 2019;16:8. https://doi.org/10.1186/s12966-019-0769-6

Insights (water)

• Fluid, cortisol and HRV: Background, from small studies: people who drank little had a bigger cortisol response to a stress test, and dehydration after exercise was followed by lower HRV. Neither looked at mild dehydration and the next morning. Kashi DS, Hunter M, Edwards JP, et al. J Appl Physiol. 2025;139(3):698–708. https://doi.org/10.1152/japplphysiol.00408.2025 · Castro-Sepúlveda M, Cerda-Kohler H, Pérez-Luco C, et al. Nutr Hosp. 2015;31(3):1273–1277. https://doi.org/10.3305/nh.2015.31.3.8523

Insights (weight)

• Glycogen and water: Background: muscle stores water with glycogen, roughly 3–4 g of water for each gram, so a rise in weight after a higher-carb day is consistent with stored glycogen and water. It isn't proof that no fat was gained. Olsson KE, Saltin B. Variation in total body water with muscle glycogen changes in man. Acta Physiol Scand. 1970;80(1):11–18. https://doi.org/10.1111/j.1748-1716.1970.tb04764.x · Review: Shiose K, Takahashi H, Yamada Y. Nutrients. 2023;15(1):155. https://doi.org/10.3390/nu15010155

Insights (fiber)

• Fiber floor: On book plans the fiber floor is the Adequate Intake: men 38 g a day (30 g over 50), women 25 g (21 g over 50). These are the app's choices when details are missing: if Apple Health doesn't give your sex, the women's values are used; without a birth date, ages 40 and over, or no age group, use the over-50 values. On the author's plan it is the author's own target. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005. https://doi.org/10.17226/10490

Help · carb-to-protein ratio

• Carbs eaten after protein: Background for the ratio Help: in a small study of adults with type 2 diabetes, eating protein and vegetables before carbohydrate lowered the rise in blood sugar after the meal. Shukla AP, Iliescu RG, Thomas CE, Aronne LJ. Food order has a significant impact on postprandial glucose and insulin levels. Diabetes Care. 2015;38(7):e98–e99. https://doi.org/10.2337/dc15-0429

Your plan's targets (Build and Clean days)

• Carb-to-protein ratio: The app's own arithmetic: the day's net carbs divided by the day's protein, both rounded to whole grams first (for example 93 g ÷ 170 g = 0.547). The ratio describes what you ate; the bands it is graded against are your plan's targets.
• Your plan's ratio, fat and calorie targets: On the book plans these are the author's plan from What I Eat; if you changed them, they are your own settings. Not a medical guideline, and how each number was first chosen was not recorded. Build and Clean are the plan's names for its two kinds of day; the app does not measure your cells. Background on the cell pathways those names refer to (not evidence that alternating these days produces those states, or for these numbers): Saxton RA, Sabatini DM. mTOR signaling in growth, metabolism, and disease. Cell. 2017;168(6):960–976. https://pmc.ncbi.nlm.nih.gov/articles/PMC5394987/ · Inoki K, Kim J, Guan KL. AMPK and mTOR in cellular energy homeostasis and drug targets. Annu Rev Pharmacol Toxicol. 2012;52:381–400. https://pubmed.ncbi.nlm.nih.gov/22017684/ · A study of protein with or without carbohydrate after one exercise session: Staples AW, et al. Med Sci Sports Exerc. 2011;43(7):1154–1161. https://pubmed.ncbi.nlm.nih.gov/21131864/

Energy balance

• Energy balance: The app's own arithmetic: food energy logged minus the energy used that day (resting plus active energy in Apple Health). Both sides are estimates, so the balance is approximate.

Siri

• Siri answers: Siri reads app and plan values: your day type and day number, your carb-to-protein ratio and its grade, and your plan's targets. Their sources are the plan entry (Your plan's ratio, fat and calorie targets) and the carb-to-protein ratio entry. Siri doesn't diagnose and reads no medical threshold.

Questions about a source: support@enqual.us