Weight Loss Calculator

To calculate your daily energy needs, metabolic scientists use validated equations to estimate your Basal Metabolic Rate (BMR)—the energy expended at rest. The Mifflin-St Jeor equation is widely considered the most accurate standard for healthy adults. The formula is calculated as follows: For men, BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5. For women, BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161. Once BMR is established, it is multiplied by an Activity Factor to determine your Total Daily Energy Expenditure (TDEE). These factors range from 1.2 for sedentary individuals (little to no exercise) to 1.9 for extremely active individuals (heavy daily exercise or physical labor). The resulting TDEE represents the number of calories required to maintain your current weight. To lose weight, you must establish a calorie deficit by consuming fewer calories than your TDEE or increasing physical activity. A safe, sustainable deficit typically ranges from 500 to 1,000 calories per day, which theoretically translates to a loss of 1 to 2 pounds (0.45 to 0.9 kg) of body fat per week. Creating a deficit larger than 1,000 calories is generally discouraged as it can lead to muscle loss, nutrient deficiencies, and a slowed metabolic rate. Consider a 35-year-old female who weighs 75 kg (165 lbs), stands 165 cm (5'5") tall, and has a moderately active lifestyle (exercising 3–5 days a week). Her BMR is calculated as: (10 × 75) + (6.25 × 165) - (5 × 35) - 161 = 750 + 1031.25 - 175 - 161 = 1,445.25 kcal. Multiplying this by her activity factor of 1.55 yields a TDEE of approximately 2,240 calories. To lose 1 pound per week, she would target a daily intake of 1,740 calories (a 500-calorie deficit).