Calorie Deficit Calculator

The calculation starts by estimating your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, which is widely considered the gold standard for clinical accuracy. For males, the formula is BMR = (10 * weight in kg) + (6.25 * height in cm) - (5 * age in years) + 5. For females, the formula adjusts the constant: BMR = (10 * weight in kg) + (6.25 * height in cm) - (5 * age in years) - 161. Next, this BMR value is multiplied by an activity factor ranging from 1.2 (sedentary) to 1.9 (extremely active) to find your Total Daily Energy Expenditure (TDEE). Finally, your customized calorie deficit is derived by comparing your TDEE against your targeted weight loss timeline and weekly rate goals.

Imagine a 30-year-old male who stands at 180 cm (1.8 meters), weighs 85 kg, and has a moderate activity factor of 1.55. His goal is to drop down to 78 kg over a period of 10 weeks (roughly 70 days). First, we calculate his maintenance calories using the male formula: (10 * 85) + (6.25 * 180) - (5 * 30) + 5 = 850 + 1125 - 150 + 5 = 1,830 kcal. Multiplying this by his activity factor of 1.55 yields a TDEE of approximately 2,836 calories per day. To lose the 7 kg weight difference over 10 weeks, the calculator determines a required daily energy deficit of roughly 770 calories, meaning his target daily intake should be around 2,066 calories.

Embarking on a weight reduction journey requires consistency and caution. Avoid dropping your calorie intake to dangerously low thresholds, as extreme restriction can impair metabolic function and lean muscle mass retention. Aim for a moderate deficit of 500 to 750 calories per day to promote sustainable weight loss of about 0.5 to 1 kg per week. Additionally, prioritize protein intake and resistance training to preserve muscle tissue while your body taps into fat reserves for energy.