How to Calculate a Calorie Deficit Safely for Weight Management

Weight loss is governed by the laws of thermodynamics: you must burn more energy than you consume. This energy shortfall is called a calorie deficit. While simple in theory, calculating a safe, sustainable deficit requires understanding your metabolism, daily activity levels, and basic nutrition.

Step 1: Calculate Your Basal Metabolic Rate (BMR)

Your BMR is the energy your body expends just to stay alive at rest. The most widely accepted formula is the Mifflin-St Jeor equation:

• Men: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (years) + 5
• Women: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (years) - 161

Step 2: Calculate Your Total Daily Energy Expenditure (TDEE)

Your TDEE is the total calories you burn in a day, including physical movement. Multiply your BMR by an activity multiplier:

• Sedentary (desk job, little exercise): BMR × 1.2
• Light Activity (light exercise 1-3 days/week): BMR × 1.375
• Moderate Activity (moderate exercise 3-5 days/week): BMR × 1.55
• Very Active (hard exercise 6-7 days/week): BMR × 1.725

Step 3: Establish a Safe Calorie Deficit

To lose roughly **1 pound (0.45 kg) of fat per week**, you need a total weekly deficit of 3,500 calories, or **500 calories per day** below your TDEE. Health experts advise against dropping below a BMR threshold, and recommends a minimum intake of **1,200 calories/day for women** and **1,500 calories/day for men** to prevent nutritional deficiency and metabolic slowdown.

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