TDEE Calculator

Understanding Energy Expenditure & TDEE

Total Daily Energy Expenditure (TDEE) represents the total number of calories your body burns in a 24-hour period. It is composed of three primary metabolic components:

1. Basal Metabolic Rate (BMR): The baseline energy required to sustain vital organ functions (brain, lungs, heart, liver) at rest.
2. Thermic Effect of Activity (TEA): Energy expended during active movement, workouts, and NEAT (Non-Exercise Activity Thermogenesis, like fidgeting or walking).
3. Thermic Effect of Food (TEF): Energy required to digest, absorb, and metabolize nutrients (protein has the highest thermic cost at ~20-30%).

The Mifflin-St Jeor Equation

Historically, metabolic calculators relied on the Harris-Benedict formula (1919). However, clinical reviews have shown that the Mifflin-St Jeor Equation (1990) offers a higher level of accuracy for modern populations, estimating energy needs within 10% of measured values.

The equation estimates BMR in metric units:

BMR (Men) = 10 * Weight (kg) + 6.25 * Height (cm) - 5 * Age (y) + 5
BMR (Women) = 10 * Weight (kg) + 6.25 * Height (cm) - 5 * Age (y) - 161

Once BMR is calculated, we multiply by the Physical Activity Level (PAL) multiplier to find your TDEE:

• Sedentary (1.2): Minimal 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.
• Extremely Active (1.9): Twice daily heavy workouts, athletic job.

Macro Distribution Strategies

Weight loss or muscle gain is fundamentally dictated by energy balance (calories in vs. calories out). However, macronutrient distribution determines whether weight lost comes from fat or muscle.

• Balanced (40% Carbs, 30% Protein, 30% Fat): Best for general athletic training, glycogen recovery, and long-term sustainability.
• Low Carb (15% Carbs, 30% Protein, 55% Fat): Optimizes insulin sensitivity, stabilizes blood sugar, and promotes lipid oxidation.
• High Protein (30% Carbs, 40% Protein, 30% Fat): Maximizes satiety, accelerates muscle recovery, and prevents lean tissue loss during a caloric deficit.