Methodology

The
Science
Behind It.

TRYFI's nutrition engine isn't a quiz-and-average system. It applies peer-validated metabolic formulas with 12 clinical input variables to generate a prescription accurate enough that dietitians have approved it.

Step 1

Basal Metabolic Rate

The Mifflin-St Jeor equation is the most validated formula for resting metabolic rate, consistently outperforming the Harris-Benedict and Katch-McArdle formulas in clinical trials.

Published in Journal of the American Dietetic Association, 1990, it has become the standard formula used by registered dietitians worldwide.

Unlike simpler calorie calculators, the equation produces a sex-stratified estimate that accounts for the physiological difference in lean mass distribution between males and females.

Mifflin-St Jeor BMR

If Male (sex = 1):

BMR = (10 × W) + (6.25 × H) − (5 × A) + 5

If Female (sex = 0):

BMR = (10 × W) + (6.25 × H) − (5 × A) − 161

W = weight in kg

H = height in cm

A = age in years

Step 2

Total Daily Energy Expenditure

CategoryDescriptionMultiplier

SedentaryDesk job, little exercise1.2×

Light1–3x/week light activity1.375×

Moderate3–5x/week exercise1.55×

ActiveHard training 6–7x/week1.725×

Very ActiveAthlete / physical job1.9×

BMR represents only the energy your body uses at complete rest. TDEE accounts for all movement — from walking to heavy training — via a validated activity factor multiplier.

TDEE Calculation

TDEE = BMR × activity_factor

For users with training_hours specified, we apply a fine-tuning modifier beyond the category alone, improving accuracy for athletes who train significantly more or less than their category average.

Step 3

Goal-Rate Calibration

The goal-rate is a continuous scale from -1.0 (aggressive deficit) to +1.0 (aggressive surplus). At the extremes, it applies a 20% caloric offset to TDEE — the clinically recommended maximum for safe body composition change.

Target Calorie Calculation

target_kcal = TDEE + (TDEE × goal_rate × 0.20)

goal_rate = -1.0 → 20% deficit (max fat loss)

goal_rate = 0.0 → maintenance

goal_rate = +1.0 → 20% surplus (max muscle gain)

Macro Split (v1 — Fixed)

protein_g = target_kcal × 0.30 / 4

fat_g = target_kcal × 0.25 / 9

carbs_g = target_kcal × 0.45 / 4

Protein × 4 kcal/g
Fat × 9 kcal/g
Carbs × 4 kcal/g

Full Variable List

12 Clinical Inputs

VariableSymbolClinical Impact

Weight (kg)WPrimary driver of BMR. Higher mass = higher resting energy requirement.

Height (cm)HContributes to lean mass estimation and surface area calculations.

Date of BirthAAge reduces BMR at a known rate. Applied as a direct multiplier reduction.

Biological SexSMen have higher muscle mass distributions; separate formula constants applied.

Activity CategoryAF5-tier multiplier (1.2 → 1.9+) applied to BMR to derive total TDEE.

Training Hours/WeekTHFine-tunes the activity multiplier beyond category alone.

Goal TypeGDetermines the direction of caloric offset — surplus, deficit, or maintenance.

Goal RateGRA -1.0 to +1.0 scale. At ±1.0, applies a 20% caloric adjustment to TDEE.

Smoker StatusSMTriggers elevated Vitamin C, B12, and antioxidant micronutrient flags.

PregnancyPRActivates Iron, Folate, Calcium, and DHA supplementation overlays.

DeficienciesDFUser-reported deficiencies (Iron, Vit D, B12 etc.) generate targeted micro flags.

Dietary TagsDTVegan, Jain, Diabetic-friendly etc. constrain the meal matching algorithm.

See It Applied to You.

Your prescription is generated in under 100ms from your inputs.