Calorie Calculator

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, cell production, and nutrient processing. It represents the minimum energy needed to keep your body functioning and typically accounts for 60-75% of your total daily calorie expenditure.

Factors that affect BMR include age (decreases with age), gender (men typically have higher BMR), body composition (more muscle = higher BMR), and genetics.

TDEE is the total number of calories you burn in a typical day. It includes your BMR plus additional calories burned through physical activity, exercise, and the thermic effect of food (energy used to digest food).

TDEE = BMR × Activity Factor. This is the number you use to determine calorie intake for your goals.

To lose weight safely, create a calorie deficit of 500-1000 calories below your TDEE. A 500 calorie daily deficit typically results in about 1 pound (0.45 kg) of weight loss per week, while a 1000 calorie deficit leads to about 2 pounds per week.

Important: Never go below 1200 calories for women or 1500 calories for men without medical supervision. Very low calorie diets can lead to nutrient deficiencies and metabolic adaptation.

The Mifflin-St Jeor equation is considered most accurate for most people and is recommended by the Academy of Nutrition and Dietetics. It was developed in 1990 and tends to be within ±10% of actual metabolic rate.

If you know your body fat percentage, the Katch-McArdle formula may be more accurate as it accounts for lean body mass. The Harris-Benedict formula is the oldest and may overestimate by 5-10%.

Macros (macronutrients) are protein, carbohydrates, and fat. They're calculated as percentages of your total daily calories:

• Protein: 4 calories per gram — essential for muscle maintenance and growth
• Carbohydrates: 4 calories per gram — primary energy source
• Fat: 9 calories per gram — hormone production and nutrient absorption

A balanced approach is 30% protein, 40% carbs, 30% fat. For weight loss, higher protein (35-40%) helps preserve muscle mass.

• Sedentary: Desk job with little to no exercise
• Lightly Active: Light exercise or walking 1-3 days per week
• Moderately Active: Moderate exercise 3-5 days per week
• Very Active: Hard exercise 6-7 days per week
• Extremely Active: Very hard exercise daily, physical job, or training twice per day

When in doubt, choose a lower activity level to avoid overestimating calorie needs.

A 1000 calorie deficit can lead to 2 pounds of weight loss per week, which is generally considered the maximum safe rate for most people. However, this aggressive approach:

• May not be suitable for everyone, especially those already at a healthy weight
• Can lead to muscle loss if protein intake isn't adequate
• May cause fatigue, irritability, and nutrient deficiencies
• Can trigger metabolic adaptation (your body burning fewer calories)

Consult a healthcare provider before starting any aggressive calorie deficit program.

Recalculate your calorie needs:

• Every 10-15 pounds (5-7 kg) of weight change
• Every 4-6 weeks if actively trying to change weight
• When your activity level changes significantly
• When you hit a weight loss plateau for more than 2-3 weeks

As your weight changes, your BMR and TDEE will also change, requiring adjusted calorie targets to continue making progress.