Scientific Basis
Every calculation in NutriPlan is grounded in peer-reviewed research. This page explains each formula, its source, and the safety rules we enforce.
1. BMR — Basal Metabolic Rate
We use the Mifflin-St Jeor equation, the most validated formula for general populations, published in the American Journal of Clinical Nutrition in 1990.
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, 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):241-7. DOI: 10.1093/ajcn/51.2.241
2. TDEE — Total Daily Energy Expenditure
TDEE is estimated by multiplying BMR by an activity factor. This accounts for the energy cost of physical activity beyond baseline metabolism.
| Level | Factor | Description |
|---|---|---|
| Sedentary | 1.20 | Desk job, no exercise |
| Lightly Active | 1.375 | 1–3 days/week light exercise |
| Moderately Active | 1.55 | 3–5 days/week moderate exercise |
| Very Active | 1.725 | 6–7 days/week hard exercise |
| Extra Active | 1.90 | Athlete, physical job |
3. Caloric Deficit & Target Calories
Based on the Wishnofsky Rule — approximately 7,700 kcal of energy deficit equals 1 kg of fat loss. This is a widely used clinical heuristic, though actual rates vary with body composition.
Daily deficit = (weight_to_lose_kg × 7,700 kcal) / goal_days
Target calories = TDEE − daily_deficit
Safety Rules (enforced by NutriPlan)
- Minimum 1,500 kcal/day for men
- Minimum 1,200 kcal/day for women
- Warning if daily deficit exceeds 1,000 kcal/day
- Hard block if daily deficit exceeds 1,200 kcal/day
- BMI <18.5 with weight-loss goal triggers medical consultation alert
Source: Wishnofsky M.
Caloric equivalents of gained or lost weight.
Am J Clin Nutr. 1958;6(5):542-6. DOI: 10.1093/ajcn/6.5.542
4. Macronutrient Split
NutriPlan uses a weight-loss optimized macro split that prioritizes protein to preserve lean muscle mass during a caloric deficit.
Protein: 30% of target calories ÷ 4 kcal/g (min 0.8g per lb body weight)
Carbohydrates: 40% of target calories ÷ 4 kcal/g
Fat: 30% of target calories ÷ 9 kcal/g
Source: Helms ER, Zinn C, Rowlands DS, Brown SR.
A systematic review of dietary protein during caloric restriction in resistance trained lean athletes.
Int J Sport Nutr Exerc Metab. 2014. DOI: 10.1123/ijsnem.2013-0054
5. BMI — Body Mass Index
BMI is calculated as weight in kilograms divided by height in meters squared. It is a population-level screening tool and does not directly measure body fat percentage.
< 18.5
Underweight
18.5 – 24.9
Normal weight
25.0 – 29.9
Overweight
≥ 30.0
Obese
Source: World Health Organization.
Obesity: preventing and managing the global epidemic.
WHO Technical Report Series 894. 2000.
Glossary of Acronyms
| Term | Full Name | Definition |
|---|---|---|
| BMR | Basal Metabolic Rate | Calories your body burns at complete rest to maintain basic functions (breathing, circulation, organ function). Represents ~60–70% of total daily calorie burn. |
| TDEE | Total Daily Energy Expenditure | Total calories burned per day, including BMR + physical activity + digestion (TEF). This is your true maintenance calorie number. |
| TEF | Thermic Effect of Food | Energy spent digesting and metabolizing food. ~10% of total calories consumed. |
| BMI | Body Mass Index | Ratio of weight to height squared. A population-level screening tool — not a direct measure of body fat or health. |
| kcal | Kilocalorie | The standard unit of food energy. What people commonly call a 'calorie' on nutrition labels is technically 1 kcal. |
| EPOC | Excess Post-exercise Oxygen Consumption | Elevated calorie burn that continues after intense exercise (especially HIIT). Colloquially called the 'afterburn effect.' |
| LBM | Lean Body Mass | Total body weight minus fat mass. Includes muscle, bone, organs, and water. Higher LBM = higher BMR. |
| WHO | World Health Organization | UN agency that sets global BMI classification standards. |
| g | Grams | Unit of weight used for macronutrient quantities. |
| oz | Ounces | Imperial unit of weight. 1 oz = 28.35 g. |
| lb | Pounds | Imperial unit of weight. 1 lb = 0.4536 kg. |
| ft / in | Feet / Inches | Imperial units of height. 1 ft = 30.48 cm; 1 in = 2.54 cm. |
NutriPlan provides educational information based on published research. It is not a substitute for advice from a registered dietitian, nutritionist, or physician. Always consult a qualified healthcare professional before making significant changes to your diet or exercise routine.