Complete TDEE Guide: Understanding Daily Energy Expenditure and Weight Management

TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day, including basal metabolism, daily activities, and exercise. Understanding your TDEE is fundamental to weight management: • Calorie intake = TDEE → Maintain weight • Calorie intake < TDEE → Weight loss (caloric deficit) • Calorie intake > TDEE → Weight gain (caloric surplus) TDEE consists of three main components: 1. BMR (Basal Metabolic Rate): About 60-70%, energy needed for basic life functions 2. TEF (Thermic Effect of Food): About 10%, energy consumed digesting food 3. Activity expenditure: About 20-30%, including exercise and daily activities

TDEE calculation has two steps: Step 1: Calculate BMR (Basal Metabolic Rate) The most commonly used Mifflin-St Jeor equation: • Male: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 5 • Female: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161 Step 2: Multiply by activity factor • Sedentary (desk job): BMR × 1.2 • Lightly active (exercise 1-3 days/week): BMR × 1.375 • Moderately active (exercise 3-5 days/week): BMR × 1.55 • Very active (exercise 6-7 days/week): BMR × 1.725 • Extremely active (athlete/physical labor): BMR × 1.9 Example: 25-year-old female, 160cm, 55kg, exercises 3 times/week BMR = 10 × 55 + 6.25 × 160 - 5 × 25 - 161 = 1,264 kcal TDEE = 1,264 × 1.55 = 1,959 kcal/day

Weight loss: • Recommended daily caloric deficit of 300-500 kcal (about 0.3-0.5 kg loss per week) • Deficits exceeding 1000 kcal are not recommended — may cause muscle loss and metabolic slowdown • Ensure adequate protein intake (1.6-2.2g per kg of body weight) to preserve muscle Muscle gain: • Recommended daily caloric surplus of 200-300 kcal • Combine with resistance training (weight lifting) • Protein intake of 1.6-2.2g per kg of body weight Weight maintenance: • Consume calories close to your TDEE • Focus on food quality and nutritional balance Important note: TDEE is only an estimate. Actual needs vary by individual. Use the calculated result as a starting point and adjust based on 2-3 weeks of weight change observations.

TDEE is not fixed — these factors all influence it: 1. Age: BMR gradually decreases with age (about 2-3% per decade) 2. Gender: Males typically have higher BMR than females (due to greater muscle mass) 3. Body composition: Muscle burns more calories than fat — more muscle means higher BMR 4. Environmental temperature: Extreme temperatures increase energy expenditure 5. Hormones: Thyroid function, stress hormones, etc. all affect metabolism 6. Dieting history: Chronic dieting can cause metabolic adaptation (adaptive thermogenesis) 7. Sleep quality: Poor sleep reduces metabolic rate and increases appetite These factors explain why TDEE calculators can only provide estimates, and real-world application requires fine-tuning based on individual responses.

Gigi Tools provides a free TDEE calculator to help you estimate your daily caloric needs: • Enter basic information (gender, age, height, weight) • Select your activity level • System instantly calculates BMR and TDEE • Also provides recommended calories for weight loss/maintenance/muscle gain • Calculations run in your browser — personal data is never uploaded Use it alongside the BMI calculator for a more comprehensive understanding of your body status and nutritional needs.