TDEE & Calorie Deficit Calculator
Calculate your Total Daily Energy Expenditure (TDEE) and Basal Metabolic Rate (BMR) using the clinically validated Mifflin-St Jeor formula. Get science-backed deficit targets and macronutrient distributions for sustainable body composition goals.
Mifflin-St Jeor Energy Expenditure Model
Real-time calculation • Dual US Imperial / Metric input standards
Calculated Energetics
Clinical Projection| Goal | Target Calories |
|---|---|
| Mild Weight Loss (~0.5 lb / 0.25 kg / wk) | 1,996 kcal/day |
| Moderate Fat Loss (~1.0 lb / 0.5 kg / wk) | 1,746 kcal/day |
| Aggressive Fat Loss (~1.5 lb / 0.75 kg / wk) | 1,496 kcal/day |
| Lean Muscle Gain (+250 kcal surplus) | 2,496 kcal/day |
Understanding the Science of Total Daily Energy Expenditure
Your Total Daily Energy Expenditure (TDEE) represents the aggregate number of calories your body expends across a 24-hour cycle. It is determined by four physiological compartments:
1. Basal Metabolic Rate (BMR)
Accounts for 60%–70% of daily energy expenditure. These are the calories required simply to sustain life (cardiac output, cellular respiration, renal filtration, and CNS function) in a thermoneutral environment.
2. Non-Exercise Activity (NEAT)
Accounts for 15%–20% of daily expenditure. Encompasses spontaneous physical activity: walking, standing, typing, maintaining posture, and fidgeting.
3. Thermic Effect of Food (TEF)
Accounts for approximately 8%–10% of intake. Energy required to digest, absorb, and metabolize nutrients. Dietary protein exhibits the highest TEF (20%–30%), followed by carbohydrates (5%–10%) and fats (0%–3%).
4. Exercise Activity (EAT)
Accounts for 5%–15% in most non-endurance individuals. Formal cardiovascular exercise, resistance training, and athletic competition.
Why HealthGood Uses the Mifflin-St Jeor Formula
In 1990, Dr. M.D. Mifflin and Dr. S.T. St Jeor published an updated resting metabolic rate equation derived from indirect calorimetry studies on 498 healthy men and women. A landmark systematic review by the American Dietetic Association (Frankenfield et al., 2005) evaluated ten predictive formulas across clinical populations and found that the Mifflin-St Jeor equation predicted RMR within 10% of measured calorimetry in 82% of non-obese and obese subjects—consistently outperforming the 1919 Harris-Benedict formula.
Clinical Caution on Extreme Calorie Deficits: While rapid fat loss may appear appealing, clinical evidence demonstrates that sustained daily caloric deficits exceeding 750 kcal significantly increase the risk of adaptive thermogenesis (metabolic slowdown), lean muscle mass catabolism, hormonal dysregulation (suppressed T3 thyroid hormone and leptin), and micronutrient deficiencies. Always maintain a minimum intake of 1,200 kcal/day for adult females and 1,500 kcal/day for adult males unless under direct inpatient physician supervision.
Scientific Citations & Clinical References:
- 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):241-247. PMID: 2305711
- Frankenfield D, Roth-Yousey L, Compher C. "Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review." J Am Diet Assoc. 2005;105(5):775-789. PMID: 15883556
- Hall KD, Heymsfield SB, Kemnitz JW, Klein S, Schoeller DA, Speakman JR. "Energy balance and its components: implications for body weight regulation." Am J Clin Nutr. 2012;95(4):989-994. PMID: 22434603