Why doesn't my TDEE match what I was told?

TDEE formulas are population averages. Individual metabolism varies by genetics, hormones, muscle mass, gut microbiome, and body temperature regulation. If your actual maintenance (verified by tracking) differs from the formula by more than 15%, use your actual tracked number.

Does TDEE change as I lose weight?

Yes — as you lose weight, TDEE decreases (lighter body burns fewer calories). Recalculate every 10-15 lbs of weight change. This is why weight loss tends to slow over time even with consistent eating — the same calorie intake becomes maintenance at a lower body weight.

How to Calculate Your TDEE: Complete Nutrition Guide

What Is TDEE?

Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period, including all activity. It's the most important number in nutrition because it defines your maintenance calories — eating at this level keeps your weight stable.

TDEE has four components: Basal Metabolic Rate (BMR, ~60-70% of TDEE), the Thermic Effect of Activity (TEA, exercise calories), Non-Exercise Activity Thermogenesis (NEAT, all non-exercise movement), and the Thermic Effect of Food (TEF, calories burned digesting food, ~10% of calories eaten).

The Mifflin-St Jeor Formula (Most Accurate)

Step 1: Calculate BMR (Basal Metabolic Rate) using Mifflin-St Jeor:

Male: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Female: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

Example: 35-year-old male, 180 lbs (81.6 kg), 5'10" (177.8 cm): BMR = 10×81.6 + 6.25×177.8 − 5×35 + 5 = 816 + 1,111 − 175 + 5 = 1,757 kcal/day

Activity Multipliers

Multiply BMR by the appropriate activity factor to get TDEE:

Sedentary (desk job, no exercise): BMR × 1.2
Lightly Active (exercise 1-3x/week): BMR × 1.375
Moderately Active (exercise 3-5x/week): BMR × 1.55
Very Active (hard exercise 6-7x/week): BMR × 1.725
Extra Active (physical job + exercise or 2x/day training): BMR × 1.9

Using our example at "moderately active": TDEE = 1,757 × 1.55 = 2,723 kcal/day

Using TDEE for Your Goal

Fat loss: Eat TDEE − 300 to −500 kcal/day (0.6-1 lb/week loss)
Muscle gain: Eat TDEE + 200 to +300 kcal/day (lean bulk)
Maintenance: Eat at TDEE, adjust as needed

Why Your TDEE May Vary

Formulas are estimates with ±10-15% accuracy. Track your actual weight for 2-3 weeks while eating a consistent calorie level, then calculate: if weight is stable, that IS your TDEE. If losing 0.5 lb/week, add 250 calories to find maintenance. Real-world tracking beats formula estimates every time.