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Calculation Methodology

How FeedAI calculates your personalized nutrition targets

Summary: FeedAI uses the Mifflin-St Jeor equation, a scientifically validated formula, to estimate your daily calorie and macronutrient needs. These calculations provide a starting point for tracking - not a medical prescription. Individual needs vary, and you should consult a healthcare provider for personalized guidance.

Overview

FeedAI calculates your personalized nutrition targets through a four-step process:

  1. Calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation
  2. Adjust for your activity level to determine Total Daily Energy Expenditure (TDEE)
  3. Modify calories based on your dietary goal (weight loss, maintenance, muscle gain, or keto)
  4. Distribute calories among macronutrients (protein, carbs, fat) according to goal-specific ratios

1Basal Metabolic Rate (BMR)

We use the Mifflin-St Jeor equation (1990), which research has shown to be the most accurate predictive equation for estimating resting energy expenditure in healthy adults.

Male: BMR = (10 x weightkg) + (6.25 x heightcm) - (5 x ageyears) + 5 Female: BMR = (10 x weightkg) + (6.25 x heightcm) - (5 x ageyears) - 161

Where weight is in kilograms, height is in centimeters, and age is in years.

This formula calculates the number of calories your body needs to maintain basic physiological functions while at complete rest - breathing, circulation, cell production, and other vital processes.

2Total Daily Energy Expenditure (TDEE)

Your BMR is multiplied by an activity factor to estimate your Total Daily Energy Expenditure - the total calories you burn in a day including physical activity.

Activity Level Multiplier Description
Sedentary 1.2 Little or no exercise, desk job
Lightly Active 1.375 Light exercise 1-3 days/week
Moderately Active 1.55 Moderate exercise 3-5 days/week
Very Active 1.725 Hard exercise 6-7 days/week
Extra Active 1.9 Very hard exercise, physical job, or training twice per day
TDEE = BMR x Activity Multiplier

Example: BMR of 1,800 calories x 1.55 (moderate) = 2,790 calories/day

3Goal-Based Calorie Adjustment

Your TDEE is adjusted based on your dietary goal to create an appropriate caloric surplus or deficit:

Dietary Goal Adjustment Rationale
Weight Loss -500 cal/day Creates ~3,500 cal/week deficit for approximately 1 lb/week loss
Maintenance No change Maintains current body weight
Muscle Gain +300 cal/day Provides caloric surplus to support muscle protein synthesis
Keto -300 cal/day Slight deficit often combined with ketogenic approach

4Macronutrient Distribution

Once your daily calorie target is determined, FeedAI distributes those calories among the three macronutrients according to your goal:

Goal Protein Carbs Fat
Weight Loss 35% 25% 40%
Maintenance 30% 30% 40%
Muscle Gain 30% 35% 35%
Keto 25% 5% 70%

Converting Percentages to Grams

To convert from percentages to grams, we use the caloric values of each macronutrient:

Protein (g) = (Target Calories x Protein%) / 4 Carbs (g) = (Target Calories x Carb%) / 4 Fat (g) = (Target Calories x Fat%) / 9

Example Calculation

Profile: 30-year-old male, 175 cm (5'9"), 75 kg (165 lbs), moderate activity, weight loss goal

  1. BMR: (10 x 75) + (6.25 x 175) - (5 x 30) + 5 = 1,698.75 ≈ 1,699 calories
  2. TDEE: 1,699 x 1.55 = 2,633.45 ≈ 2,633 calories
  3. Goal Adjustment: 2,633 - 500 = 2,133 calories
  4. Macros:
    • Protein (35%): (2,133 x 0.35) / 4 = 186.6 ≈ 187g
    • Carbs (25%): (2,133 x 0.25) / 4 = 133.3 ≈ 133g
    • Fat (40%): (2,133 x 0.40) / 9 = 94.8 ≈ 95g

Fiber Targets

Alongside your macros, FeedAI tracks dietary fiber against a daily target. The default target is 28 grams per day, the reference intake based on NIH Dietary Reference Intake (DRI) guidance for adults on a 2,000-calorie diet.

Per-Day Dynamic Goals (Premium)

With FeedAI Premium, connected AI assistants (Claude or ChatGPT, via the FeedAI MCP server) can set macro targets for individual days. This enables day-by-day periodization - more carbs before a hard workout, tighter calories on rest days - without changing your standing goals.

Every AI-set goal includes a written rationale that is visible in the app, so you always know why a given day's targets differ from your usual numbers.

How targets are resolved for any given day:

  1. Per-day goal - a target set specifically for that date (by you or a connected AI)
  2. Standing goal - your saved custom targets, if you have set any
  3. Calculated defaults - the targets computed by the four-step methodology above

Nutrient Limits & Sources

Some nutrients are tracked as limits rather than goals. Limit ("budget") rings fill as you approach a daily cap, helping you stay under it rather than reach it. FeedAI's default caps come from published guidance:

Nutrient Daily Limit Source
Added Sugar 25g (women) / 36g (men) American Heart Association
Saturated Fat 20g FDA Daily Value
Sodium 2,300mg FDA
Caffeine 400mg FDA

Micronutrients tracked as targets use NIH Recommended Dietary Allowance (RDA) values for adults:

Micronutrient Daily Target (NIH RDA)
Potassium 3,400mg
Calcium 1,000mg
Magnesium ~400mg
Iron 8mg (men) / 18mg (women)
Vitamin D 600 IU
Vitamin B12 2.4mcg

Note: These limits and targets are general guidance for healthy adults, not medical advice. Individual needs vary with age, health conditions, medications, pregnancy, and activity level - consult a healthcare provider for personalized recommendations.

Limitations

Important: These calculations are estimates based on population averages and validated formulas. They do not account for:

  • Individual metabolic variations
  • Medical conditions affecting metabolism (thyroid disorders, PCOS, etc.)
  • Medications that affect weight or appetite
  • Genetic factors influencing metabolism
  • Hormonal variations and fluctuations
  • Pregnancy, nursing, or postpartum recovery
  • Age-related metabolic changes beyond the formula's scope
  • Body composition (muscle vs. fat ratio)

Important Disclaimer

This is not medical advice.

The calculations provided by FeedAI are general estimates based on scientific formulas and are intended to help you track your nutrition intake. They are not personalized medical recommendations and should not be used to diagnose, treat, cure, or prevent any health condition.

Before making significant dietary changes, especially if you have health conditions, are pregnant, nursing, or taking medications, please consult with a qualified healthcare provider, registered dietitian, or nutrition professional.

FeedAI is a nutrition tracking tool, not a medical device. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or dietary changes.

Scientific Sources

The methodologies used in FeedAI are based on peer-reviewed scientific research:

  1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO.
    "A new predictive equation for resting energy expenditure in healthy individuals."
    American Journal of Clinical Nutrition. 1990;51(2):241-247.
    PubMed: 2305711
  2. Harris JA, Benedict FG.
    "A Biometric Study of Human Basal Metabolism."
    Proceedings of the National Academy of Sciences of the USA. 1918;4(12):370-373.
    PMC1091498
    Included as historical background only - FeedAI uses the Mifflin-St Jeor equation, not Harris-Benedict.
  3. U.S. Department of Agriculture and U.S. Department of Health and Human Services.
    "Dietary Guidelines for Americans, 2025-2030."
    10th Edition. December 2025.
    DietaryGuidelines.gov
  4. Frankenfield D, Roth-Yousey L, Compher C.
    "Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review."
    Journal of the American Dietetic Association. 2005;105(5):775-789.
    PubMed: 15883556

Last Updated: August 5, 2026 | Document ID: FEEDAI-METH-2025-001