Nutrition Sources
How Luko gets the numbers
Luko uses established nutrition science for your daily plan, AI-assisted estimates when you log meals, and estimated burn for Workout with Luko sessions. Homestead Planet weather is a decorative scene effect, not a calorie or recovery number. Numbers are estimates to help you build awareness — not medical advice. For health conditions, pregnancy, injuries, or clinical diets, talk with a qualified clinician.
1. Your daily calorie budget
Your target is personalized from the profile you set in onboarding (and can adjust in Settings): age, sex, height, weight, activity, and goal.
Resting energy (BMR)
We estimate basal metabolic rate with the Mifflin–St Jeor equation:
- Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
- Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
Source: Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.
Daily energy need (TDEE)
BMR is multiplied by an activity factor (same family as common Harris–Benedict / FAO-style multipliers):
| Activity (as asked in Luko) | Multiplier |
|---|---|
| Little / sedentary (default) | 1.2 |
| 2–3× per week | 1.375 |
| 4–5× per week | 1.55 |
| 6–7× per week | 1.725 |
Background: Harris JA, Benedict FG. A Biometric Study of Human Basal Metabolism. Proc Natl Acad Sci USA. 1918;4(12):370–373. Modern activity factors are widely used adaptations of that tradition (e.g. FAO/WHO/UNU energy requirement frameworks).
Goal adjustment
| Goal | Calorie adjustment vs estimated maintenance |
|---|---|
| Lose weight | ~20% below TDEE (×0.8) |
| Maintain | TDEE (×1.0) |
| Gain / build muscle | ~10% above TDEE (×1.1) |
| General health (default) | TDEE (×1.0) |
Moderate deficits/surpluses are preferred over extreme cuts. Rapid loss is harder to sustain and more likely to reduce lean mass.
Related reading: Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826–837. Dietary Guidelines for Americans (current edition) — healthy adult calorie ranges and sustainable weight management.
Safety floors
We never set a target below:
- the higher of ~80% of BMR, or
- 1,200 kcal/day (women) / 1,500 kcal/day (men)
Very low intakes raise deficiency risk. Settings copy already notes a general adult range of about 1,600–3,000 kcal/day.
Background: Institute of Medicine / National Academies guidance on energy and nutrient adequacy; clinical practice commonly uses similar minimums for unsupervised adult plans.
2. Macronutrients (protein, carbs, fat)
Energy from macros (Atwater factors)
When we convert between grams and calories:
- Protein ≈ 4 kcal/g
- Carbohydrate ≈ 4 kcal/g
- Fat ≈ 9 kcal/g
Source: Atwater WO. Principles of Nutrition and Nutritive Value of Food. USDA Farmers’ Bulletin No. 142 (and later USDA adaptations). Still the standard used on nutrition labels in many countries.
How Luko builds the split
- Protein first — grams from body weight × a goal-based rate (g/kg), then boosted slightly for higher activity, and +10% if age ≥ 65.
- Remaining calories — split between fat and carbs (fat share of remaining calories depends on goal; carbs take the rest).
Illustrative protein rates used in-app (before activity/age boosts):
| Goal | Protein (g/kg body weight) |
|---|---|
| Lose weight | ~2.2 |
| Gain muscle | ~2.0 |
| Maintain | ~1.8 |
| General health | ~1.4 |
Scientific context:
- International protein RDA is often cited near 0.8 g/kg for sedentary healthy adults (IOM / WHO) — a minimum, not an optimal sports/weight-loss target.
- Higher intakes (~1.6–2.2 g/kg) are commonly studied for preserving lean mass in deficit or supporting resistance training (Phillips / Helms and related work).
- Older adults often benefit from higher protein (PROT-AGE recommendations).
Fat and carb shares are chosen so the day still adds up to your calorie target; they are planning defaults, not medical prescriptions. You can override the % split in Settings → Macronutrients.
AMDR context (adult Acceptable Macronutrient Distribution Ranges, IOM): roughly carbs 45–65%, fat 20–35%, protein 10–35% of energy — Luko’s goal-based plans are meant to stay in a practical band within that spirit, not to replace clinical dietetics.
3. Fiber
Onboarding sets a default fiber target of 25 g/day.
Settings guidance (aligned with U.S. Dietary Guidelines–style ranges):
- Women < 50: ~25–28 g
- Men < 50: ~31–34 g
- Women ≥ 51: ~22 g
- Men ≥ 51: ~28 g
Sources: Dietary Guidelines for Americans; Institute of Medicine Adequate Intake for total fiber (~14 g per 1,000 kcal historically used as a basis).
4. BMI (context only)
BMI = weight(kg) / height(m)², with adult labels:
- < 18.5 Underweight
- 18.5–24.9 Healthy range
- ≥ 25 Overweight (app uses a simplified “Overweight” band above 25)
Source: WHO. Obesity: preventing and managing the global epidemic / WHO BMI classification for adults.
BMI is a population screening tool. It does not measure body fat, muscle, or health by itself. Luko may show reminders for very low or high target BMIs; it does not diagnose.
5. Weight-change pace
Onboarding pace options map to approximate weekly change:
| Pace | ~kg / week |
|---|---|
| Slow | 0.25 |
| Balanced | 0.5 |
| Speedy | 0.8 |
Settings currently suggests a gentler band (~0.13–0.25 kg/week) in the weight-plan callout — prefer the slower end if you’re unsure.
Background: Many public-health programs suggest about 0.5–1 lb (≈0.2–0.5 kg) per week as a sustainable loss rate; faster rates need more supervision. See CDC healthy weight guidance and Dietary Guidelines discussions of gradual change.
Goal-date estimates assume steady weekly change; real progress varies with adherence, water, hormones, and measurement noise.
6. Meal logging: calories & macros on food
| Method | How numbers are produced |
|---|---|
| Scan (photo) | Backend AI analyzes the image (food_scan) and returns estimated items + calories/macros. |
| Describe (text) | Backend AI structures your description (food_text) into items + estimates. |
| Manual entry | You enter calories and macros; Luko stores them as-is (no AI rewrite). |
Estimates depend on what the model can see or parse: portion size, preparation, sauces, and packaging all affect accuracy. You can edit items and servings before confirming so daily totals stay closer to what you ate.
Meal nutrition is AI-estimated from your photo or description, then editable by you. Treat logged values as guidance for trends, not lab assays.
Related science on estimation error: Self-reported and photo-based intake often misestimates portions; editing servings improves usefulness for tracking trends (see literature on dietary assessment error, e.g. work by Livingstone / Subar on underreporting).
7. Workout estimated burn
When you finish or save a Workout with Luko session, Luko may show an estimated calorie burn for the completed work. That number is produced by our servers from the session snapshot (exercises completed, prescription, duration) — it is not measured from heart rate, Apple Health / HealthKit, a wearable, or continuous motion sensors.
Treat burn estimates like meal nutrition estimates: useful for trends and motivation, not lab calorimetry. Individual energy cost varies with body size, intensity, form, rest, and other factors the app does not measure.
8. Planet weather (not a nutrition number)
If you allow Apple Health / HealthKit, Adventure may change the Homestead Planet’s decorative weather from sleep, steps, active energy, workouts, heart rate, and heart-rate variability already on your iPhone. That derivation stays on the device. It is not a measured calorie burn, readiness score, or medical reading, and it is not used to set your food plan.
Workout estimated burn (section 7) is still computed from the Luko session snapshot on our servers. It does not come from HealthKit.
9. What Luko is — and isn’t
- Is: A planning and logging companion using published energy equations, common activity factors, Atwater macro math, AI meal estimates, and session-based workout burn estimates, plus a decorative Planet that can react to on-device HealthKit patterns.
- Isn’t: A substitute for medical nutrition therapy, clinical exercise prescription, diagnosis, or treatment.
- Your control: You can change calorie target, macro %, fiber, activity, and weight plan in Settings; you can correct any meal before it counts toward the day; you can edit or skip workout steps before they are logged; you can decline HealthKit or location and still use Adventure.
Key references (short list)
- Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990 — resting energy equation.
- Harris JA, Benedict FG. PNAS. 1918 — foundational BMR work (activity multipliers are later practice).
- Atwater / USDA — metabolizable energy factors (4 / 4 / 9).
- Institute of Medicine — DRIs / AMDRs for macronutrients; fiber AI.
- WHO — adult BMI classification.
- Dietary Guidelines for Americans (current) — calorie ranges, fiber, sustainable weight change.
- Phillips / Helms / PROT-AGE — higher protein in sport, deficit, and older adults.
- Hall KD, et al. Lancet. 2011 — energy imbalance and body weight dynamics.
- USDA FoodData Central — (cite only if backend confirms use).