TDEE Calculator

The Mifflin-St Jeor equation is recognized by the Academy of Nutrition and Dietetics as the clinical gold standard for estimating Basal Metabolic Rate (BMR) in both non-obese and obese adults. Published in 1990, extensive indirect calorimetry research demonstrates that it predicts resting metabolic rate within ±10% for over 82% of individuals, delivering consistently superior accuracy without needing costly body composition scans.

• •Clinical gold standard recommended by the Academy of Nutrition and Dietetics
• •Demonstrated ±10% indirect calorimetry accuracy for over 82% of individuals tested
• •Reliably balances weight, height, age, and biological sex without equipment requirements

Overestimating activity is the number one reason people fail to see anticipated weight loss. If you work a seated office job and lift weights for 45 minutes 3 to 4 days a week, your overall daily classification is usually "Light Activity" or "Moderate Activity", not "Heavy". When in doubt, start with one tier lower than you think. You can monitor your average scale weight over 2 to 3 weeks and adjust your calorie intake based on real-world trends.

• •Sedentary: Desk jobs with under 5,000 steps per day and no structured training
• •Light Activity: 5,000–7,500 daily steps or 1–2 days of light recreational exercise
• •Moderate Activity: 7,500–10,000 daily steps plus 3–5 workouts per week
• •Heavy Activity: 10,000–12,500+ daily steps, hard manual labor, or 6–7 daily sports training sessions

A moderate deficit of 20% below your TDEE—typically 300 to 500 calories per day—is clinically recommended for sustainable fat loss. This target yields an approximate loss of 0.5 to 1.0 pound (0.25 to 0.5 kg) per week while minimizing muscle catabolism, hormonal disruption, and metabolic adaptation. Aggressive deficits greater than 750 kcal/day often trigger intense hunger signals and rapid loss of lean tissue.

• •Mild Deficit (-250 kcal/day): Gradual loss of ~0.5 lb/week with near-zero hunger or training decline
• •Moderate Deficit (-500 kcal/day): The sweet spot of ~1.0 lb/week for optimal fat-to-muscle loss ratio
• •Aggressive Deficit (-750 kcal/day): Fast initial results but higher risk of fatigue and muscle loss
• •Safety floors: Do not consume less than 1,200 kcal/day (women) or 1,500 kcal/day (men) without clinical supervision

Metabolic adaptation is real, though popular media exaggerates it as "starvation mode." As you lose weight, your body burns fewer calories because your physical mass is smaller, and your autonomic nervous system unconsciously downregulates Non-Exercise Activity Thermogenesis (NEAT)—causing you to fidget less and rest more. Leptin and thyroid hormones also dip slightly. This means your TDEE naturally decreases as weight drops, requiring recalculated calorie targets every 10 to 15 pounds lost.

• •A smaller body requires fewer calories to move and function
• •Unconscious movement (NEAT) drops during prolonged caloric deficits
• •Periodic maintenance diet breaks (1–2 weeks) can help restore energy and hormone levels

When eating in a caloric deficit, protein requirements increase to safeguard skeletal muscle tissue from being catabolized for fuel. Sports nutrition guidelines recommend 0.7 to 1.0 grams of protein per pound of body weight (1.6 to 2.2 grams per kg). For individuals with higher body fat, calculating 1.0 gram per pound of Lean Body Mass (LBM) provides an ideal benchmark.

• •0.7 to 1.0 grams per pound of body weight is optimal for muscle retention
• •Protein carries the highest Thermic Effect of Food (TEF), burning 20–30% of its calories during digestion
• •High protein intake significantly boosts satiety and suppresses ghrelin (the hunger hormone)

For pure fat loss or muscle gain, total caloric intake and adequate protein matter substantially more than the specific carb-to-fat ratio. A balanced split (30% protein, 30% fat, 40% carbs) provides consistent energy and flexibility. Athletes engaging in high-intensity anaerobic training or crossfit often perform best on a higher-carb split, while individuals with insulin resistance or sedentary routines may prefer a low-carb model.

• •Calorie balance and daily protein intake dictate 90% of body composition changes
• •Carbohydrates fuel glycogen stores and high-intensity workout performance
• •Dietary fats are essential for steroid hormone synthesis and fat-soluble vitamin absorption

To build muscle while minimizing fat accumulation (a "lean bulk"), aim for a conservative surplus of 200 to 300 calories per day above your maintenance TDEE. Muscle protein synthesis has an upper biological rate limit; consuming a 1,000-calorie surplus will not build muscle four times faster—it will simply deposit the excess surplus into adipose fat reserves.

• •Surplus of +200 to +300 kcal/day is ideal for lean muscle hypertrophy
• •Target weight gain of 0.25 to 0.5 lb (0.1 to 0.25 kg) per week for natural lifters
• •Combine with progressive resistance training and minimum 0.8g protein per pound of body weight