What Are TDEE and BMR?
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — just to keep organs functioning, maintain body temperature, and support cellular processes. Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor to account for movement throughout the day. TDEE is your maintenance calories: eating exactly this amount keeps your weight stable.
The Mifflin-St Jeor Equation
The most accurate BMR formula for most adults is the Mifflin-St Jeor equation, validated in a 2005 Journal of the American Dietetic Association study as accurate within 10% for 82% of non-obese subjects. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161.
Activity Multipliers: Choosing the Right One
The most common mistake in TDEE calculation is choosing too high an activity level. Be honest about your actual daily activity:
- Sedentary (×1.2): Desk job, less than 30 minutes of deliberate exercise per week.
- Lightly active (×1.375): Light exercise 1–3 days per week, or a job with some walking.
- Moderately active (×1.55): Exercise 3–5 days per week at moderate intensity.
- Very active (×1.725): Hard exercise 6–7 days per week, or physical job.
- Extra active (×1.9): Twice-daily training, very physical labor, or competitive athlete.
Setting Your Calorie Goal
For fat loss, subtract 500 calories from your TDEE to lose approximately 0.5 kg (1 lb) per week — a sustainable rate that minimizes muscle loss. Never go below 1,200 calories for women or 1,500 for men without medical supervision. For muscle gain, add 250–500 calories above TDEE. A smaller surplus (250 cal) produces slower but leaner gains; a larger surplus (500 cal) builds faster but with more fat. For maintenance, eat at your TDEE.
Why Your Calorie Needs Change Over Time
Your TDEE is not fixed. As you lose weight, your BMR decreases because there is less tissue to maintain. After 10–15 lbs of weight loss, recalculate your TDEE and adjust your target accordingly. Metabolic adaptation — the body's survival response to sustained calorie restriction — also reduces TDEE by 5–15% beyond what weight loss alone predicts. This is why diet breaks and refeed periods are used by experienced coaches.
Frequently Asked Questions
How many calories should I eat to lose weight?+
A deficit of 500 calories per day below your TDEE produces approximately 0.5 kg or 1 pound of fat loss per week. This is the widely recommended rate for sustainable fat loss with minimal muscle loss. More aggressive deficits increase weight loss speed but raise risks.
Is the calorie calculator accurate for everyone?+
The Mifflin-St Jeor formula estimates BMR within 10% accuracy for most non-obese adults. Your true TDEE is best determined by tracking calories at the calculated maintenance level for two weeks and adjusting based on actual weight changes.
What is the minimum safe calorie intake?+
1,200 calories per day for women and 1,500 for men are commonly cited minimums for meeting essential micronutrient needs without supplementation. Below these levels, vitamin and mineral deficiencies become likely without careful planning.
Should I eat back exercise calories?+
Activity multipliers in TDEE calculations already account for regular exercise. If you use the sedentary multiplier and track exercise separately, add a portion back. Most fitness trackers significantly overestimate calorie burn, so adding back only 50–75% of tracked exercise calories is advisable.
How does age affect calorie needs?+
Metabolism slows approximately 1–2% per decade after age 20, primarily due to muscle mass loss. A 50-year-old typically needs 100–200 fewer calories per day than a 25-year-old of identical height, weight, and activity level. Resistance training to preserve muscle mass is the most effective way to counteract this decline.
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Written & Reviewed by Team Cloud Calculators App
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Our team specializes in financial planning, health & fitness metrics, and applied mathematics. Every article is written against authoritative sources including peer-reviewed studies, WHO guidelines, IRS publications, and NIST standards. All formulas are independently verified before publication.