BMR TDEE Calculator 2025 | Basal Metabolic Rate & Calorie Needs Calculator

Understanding BMR, TDEE, and Daily Calorie Needs: A Comprehensive Guide to Energy Expenditure

Last updated: December 11, 2025

Your body requires energy (calories) every day to function, even when you're completely at rest. Understanding your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) helps you estimate how many calories your body needs to maintain, lose, or gain weight. BMR represents the calories your body burns at complete rest for essential functions like breathing, circulating blood, and maintaining organ function. TDEE includes BMR plus all calories burned through daily activities and exercise, representing your total daily calorie burn.

Whether you're a student learning about nutrition, a professional managing weight, a researcher studying metabolism, a taxpayer evaluating health costs, or a common person interested in understanding calorie needs, BMR and TDEE provide valuable insights into energy expenditure. BMR accounts for approximately 60-75% of your total daily calorie burn, while physical activity accounts for the remaining 25-40%. Understanding these metrics helps you make informed decisions about diet, exercise, and weight management goals.

Our BMR / TDEE and Calorie Needs Calculator helps you estimate your BMR, TDEE, and daily calorie ranges for different goals. Simply enter your age, sex, height, weight, and activity level, and the calculator automatically computes your BMR using the Mifflin-St Jeor equation (one of the most accurate BMR formulas), calculates your TDEE by multiplying BMR by an activity multiplier, and provides calorie ranges for maintaining weight, gentle weight loss, and gentle weight gain. The calculator works with both metric and US units.

This tool is perfect for anyone who wants to understand their energy needs, set realistic calorie goals, plan meals, track progress, and make informed decisions about diet and exercise. By calculating BMR and TDEE, you can determine how many calories to consume to maintain, lose, or gain weight. Remember, these are estimates based on standard equations—always consult registered dietitians or healthcare professionals for personalized nutrition guidance, especially if you have medical conditions, are pregnant, breastfeeding, or are an athlete. This calculator is for educational purposes only and does not provide medical or nutrition advice.

Understanding the Basics: BMR, TDEE, and Activity Levels

Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest—lying in bed, doing nothing, in a temperature-controlled environment. It represents the energy needed for essential bodily functions like breathing, circulating blood, regulating body temperature, cell production, brain function, and maintaining organ function. BMR accounts for approximately 60-75% of your total daily calorie burn and is influenced by age, sex, height, weight, and body composition (muscle mass vs. fat mass).

Activity Level Multipliers for TDEE

Activity Level	Multiplier	Description
Sedentary	1.2x	Little or no exercise, desk job
Lightly Active	1.375x	Light exercise 1-3 days/week
Moderately Active	1.55x	Moderate exercise 3-5 days/week
Very Active	1.725x	Hard exercise 6-7 days/week
Extra Active	1.9x	Very hard exercise or physical job

How BMR and TDEE Relate to Weight Management

Understanding BMR and TDEE helps you manage weight:

Maintain Weight: Eat approximately your TDEE. Consuming the same calories you burn maintains current weight.
Lose Weight: Eat less than your TDEE (calorie deficit). A deficit of 500 calories/day typically results in losing about 1 pound per week.
Gain Weight: Eat more than your TDEE (calorie surplus). A surplus of 500 calories/day typically results in gaining about 1 pound per week.

Example: If your TDEE is 2,000 calories/day, eating 2,000 calories maintains weight, eating 1,500 calories (500 deficit) promotes weight loss, and eating 2,500 calories (500 surplus) promotes weight gain.

Factors That Affect BMR

Several factors influence your BMR:

Age: BMR decreases with age (typically 1-2% per decade) due to muscle loss and metabolic changes.
Sex: Men typically have higher BMR than women due to generally higher muscle mass and larger body size.
Height and Weight: Larger bodies require more energy. Taller and heavier people have higher BMR.
Muscle Mass: Muscle burns more calories at rest than fat. Higher muscle mass increases BMR.
Genetics: Some people naturally have faster or slower metabolisms due to genetic factors.

Step-by-Step Guide: How to Use This Calculator

Step 1: Select Measurement System
Choose between metric (kilograms and centimeters) or US units (pounds and inches). The calculator works with both systems and automatically converts between them. Select the system you're most comfortable with or that matches your measuring tools.

Step 2: Enter Your Age
Enter your age in years. The Mifflin-St Jeor equation is designed for adults (18+). BMR decreases with age, so accurate age ensures accurate calculations. If you're under 18 or over 80, results may be less accurate.

Step 3: Select Sex at Birth
Select your sex at birth (male or female). BMR equations differ for men and women because men typically have higher muscle mass and larger body size. Accurate sex information ensures accurate BMR calculation.

Step 4: Enter Your Height
For metric: Enter your height in centimeters (e.g., 175 cm). For US units: Enter your height in feet and inches (e.g., 5 feet 9 inches). Be as accurate as possible—measure your height without shoes, standing straight. Accurate height is crucial for accurate BMR calculation.

Step 5: Enter Your Weight
For metric: Enter your weight in kilograms (e.g., 70 kg). For US units: Enter your weight in pounds (e.g., 154 lbs). Weigh yourself on a reliable scale, ideally at the same time of day (morning is often most consistent) and without heavy clothing. For most accurate results, use your current weight.

Step 6: Select Activity Level
Choose the activity level that best matches your lifestyle: Sedentary (1.2x), Lightly Active (1.375x), Moderately Active (1.55x), Very Active (1.725x), or Extra Active (1.9x). Be honest about your activity level—overestimating leads to overestimated TDEE and calorie needs. If you're between categories, choose the lower one for a conservative estimate.

Step 7: Review Your Results
The calculator displays: (1) BMR: Calories burned at rest (e.g., 1,500 kcal/day). (2) TDEE:Total daily calorie burn including activity (e.g., 2,325 kcal/day). (3) Calorie Ranges: For maintaining weight (TDEE), gentle weight loss (TDEE - 250 to 500), and gentle weight gain (TDEE + 250 to 500). Use these ranges as starting points for your nutrition plan.

Formulas and Behind-the-Scenes Logic

This calculator uses the Mifflin-St Jeor equation to compute BMR and activity multipliers to calculate TDEE. Here's how it works:

BMR Calculation: Mifflin-St Jeor Equation

The Mifflin-St Jeor equation is considered one of the most accurate BMR formulas for adults:

For Males: BMR = 10 × Weight(kg) + 6.25 × Height(cm) - 5 × Age(years) + 5

For Females: BMR = 10 × Weight(kg) + 6.25 × Height(cm) - 5 × Age(years) - 161

Example (Male): Age 30, weight 70 kg, height 175 cm. BMR = (10 × 70) + (6.25 × 175) - (5 × 30) + 5 = 700 + 1,093.75 - 150 + 5 = 1,648.75 kcal/day. Rounded: 1,649 kcal/day.

Example (Female): Age 30, weight 65 kg, height 165 cm. BMR = (10 × 65) + (6.25 × 165) - (5 × 30) - 161 = 650 + 1,031.25 - 150 - 161 = 1,370.25 kcal/day. Rounded: 1,370 kcal/day.

TDEE Calculation: Activity Multipliers

TDEE is calculated by multiplying BMR by an activity multiplier:

TDEE = BMR × Activity Multiplier

Activity Multipliers:

Sedentary: 1.2, Light: 1.375, Moderate: 1.55, Very Active: 1.725, Extra Active: 1.9

Example: BMR 1,649 kcal/day, Moderately Active (1.55x). TDEE = 1,649 × 1.55 = 2,555.95 kcal/day. Rounded: 2,556 kcal/day.

Calorie Range Calculations

The calculator determines calorie ranges for different goals:

Maintain Weight: TDEE (no adjustment)

Gentle Weight Loss: TDEE - 500 to TDEE - 250

Gentle Weight Gain: TDEE + 250 to TDEE + 500

Example: TDEE 2,556 kcal/day. Maintain: 2,556 kcal. Loss: 2,056-2,306 kcal. Gain: 2,806-3,056 kcal.

Complete Worked Example

Setup: 35-year-old female, weight 68 kg, height 168 cm, Moderately Active.

BMR Calculation:

BMR = (10 × 68) + (6.25 × 168) - (5 × 35) - 161
BMR = 680 + 1,050 - 175 - 161
BMR = 1,394 kcal/day

TDEE Calculation:

TDEE = 1,394 × 1.55 (Moderately Active)
TDEE = 2,160.7 kcal/day
Rounded: 2,161 kcal/day

Calorie Ranges:

Maintain: 2,161 kcal/day
Gentle Loss: 1,661-1,911 kcal/day
Gentle Gain: 2,411-2,661 kcal/day

Practical Use Cases: Real-World Scenarios

Here are detailed scenarios showing how different people might use this BMR/TDEE calculator to understand their calorie needs:

1. Student Planning Weight Loss

Sarah, a 22-year-old college student, wants to lose weight. She enters: age 22, sex female, height 165 cm, weight 75 kg, activity level Lightly Active. The calculator shows: BMR 1,512 kcal, TDEE 2,079 kcal. For gentle weight loss: 1,579-1,829 kcal/day. She uses this range to plan meals, aiming for 1,700 kcal/day to create a sustainable deficit. She tracks calories using a food app and adjusts based on results.

2. Professional Maintaining Weight

Michael, a 35-year-old office worker, wants to maintain his current weight. He enters: age 35, sex male, height 178 cm, weight 80 kg, activity level Moderately Active. The calculator shows: BMR 1,768 kcal, TDEE 2,740 kcal. To maintain: ~2,740 kcal/day. He uses this as a target for daily calorie intake, tracking meals to ensure he stays around this number. He maintains weight successfully by eating approximately his TDEE.

3. Researcher Studying Metabolism

Dr. Chen is researching energy expenditure in different populations. They use the calculator to compute BMR and TDEE for various age/sex/height/weight/activity combinations to understand energy needs. They find that BMR varies significantly by age, sex, and body size, while TDEE varies by activity level. The calculator helps them quickly compute estimates and understand how different factors affect calorie needs, supporting their research on nutrition and metabolism.

4. Tax Payer Evaluating Health Costs

Robert is evaluating his health to understand potential healthcare costs. He enters: age 42, sex male, height 180 cm, weight 95 kg, activity level Sedentary. The calculator shows: BMR 1,939 kcal, TDEE 2,327 kcal. He realizes his sedentary lifestyle results in lower TDEE, which may contribute to weight gain and health issues. He uses this information to motivate lifestyle changes, increasing activity to raise TDEE and reduce future healthcare costs.

5. Common Person Planning Muscle Gain

Lisa wants to build muscle. She enters: age 28, sex female, height 170 cm, weight 60 kg, activity level Very Active. The calculator shows: BMR 1,373 kcal, TDEE 2,368 kcal. For gentle weight gain: 2,618-2,868 kcal/day. She uses this range to plan meals, aiming for 2,700 kcal/day with adequate protein (1.6g/kg body weight) to support muscle growth. Combined with strength training, she successfully gains muscle while staying within the calorie range.

6. Person Recalculating After Weight Loss

James lost 20 lbs and wants to recalculate his calorie needs. He originally had: age 30, sex male, weight 200 lbs, TDEE 2,800 kcal. After weight loss: weight 180 lbs. New BMR: 1,789 kcal (down from 1,956), TDEE: 2,774 kcal (down from 2,800). He realizes his calorie needs decreased with weight loss, so he adjusts his intake accordingly. He recalculates every 10-20 lbs to ensure accurate calorie targets.

7. Person Adjusting Activity Level

Maria increased her exercise from 2 days/week to 5 days/week. She recalculates: age 32, sex female, height 163 cm, weight 70 kg, activity level changed from Lightly Active to Moderately Active. Original TDEE: 2,080 kcal. New TDEE: 2,340 kcal (increase of 260 kcal). She adjusts her calorie intake to account for increased activity, allowing her to eat more while maintaining or losing weight. The calculator helps her understand how activity affects calorie needs.

Common Mistakes to Avoid

• Overestimating Activity Level: Many people overestimate their activity level, leading to overestimated TDEE and calorie needs. Be honest about your activity—if you exercise 3 days/week, you're Moderately Active, not Very Active. Overestimating activity leads to eating too many calories, which can prevent weight loss or cause weight gain. Choose the activity level that best matches your actual lifestyle, not your ideal lifestyle.

• Using Outdated Weight or Measurements: Many people use old weight or height measurements, leading to inaccurate BMR and TDEE calculations. Always use current, accurate measurements. Weigh yourself on a reliable scale and measure height without shoes. If you've lost or gained significant weight, recalculate your BMR and TDEE to ensure accurate calorie targets.

• Treating Calculator Results as Exact Numbers: BMR and TDEE calculators provide estimates, not exact numbers. Your actual calorie needs may be 10-15% higher or lower than calculated. Don't treat the calculator results as strict rules—use them as starting points and adjust based on real-world results. Track your food intake and weight changes to see if you need to adjust your calorie target.

• Not Recalculating After Weight Changes: As you lose or gain weight, your BMR changes (smaller body = lower BMR, larger body = higher BMR). Many people don't recalculate after significant weight changes, leading to inaccurate calorie targets. Recalculate your BMR and TDEE every 10-20 lbs of weight change to ensure accurate targets. If you're actively losing or gaining weight, recalculate regularly.

• Eating Too Few Calories for Weight Loss: Many people think eating very few calories (e.g., 1,000 kcal/day) will speed up weight loss, but this can be counterproductive. Very low calorie intakes can lead to muscle loss, slowed metabolism, nutrient deficiencies, and fatigue. Aim for a modest deficit (250-500 calories below TDEE) rather than extreme restriction. The calculator warns if calorie ranges fall below 1,200 kcal/day.

• Ignoring Other Factors That Affect Metabolism: The calculator uses standard equations, but many factors affect actual calorie needs: muscle mass, medical conditions, medications, genetics, sleep, stress, and more. Don't assume the calculator accounts for all factors—if you have medical conditions, are pregnant, breastfeeding, or are an athlete, consult healthcare professionals for personalized guidance.

• Not Tracking Food Intake Accurately: Many people underestimate portion sizes or forget to track snacks, leading to inaccurate calorie tracking. If you're not seeing expected results, inaccurate food tracking may be the issue. Use a food scale, measure portions, and track everything (including drinks, condiments, and snacks). Accurate tracking is essential for successful weight management.

Advanced Tips & Strategies

• Track Your Results and Adjust: Use the calculator as a starting point, then track your actual food intake and weight changes over 2-4 weeks. If you're not seeing expected results (e.g., not losing weight on a deficit), adjust your calorie target. You may need to reduce calories further, increase activity, or reassess your activity level. Real-world results are more important than calculator estimates.

• Recalculate After Significant Changes: Recalculate your BMR and TDEE when: (1) Your weight changes significantly (10+ lbs), (2) Your activity level changes substantially, (3) You age (though age-related changes are gradual). As you lose weight, your BMR decreases, so you may need to reduce calorie intake further to continue losing. Regular recalculation ensures accurate targets.

• Use TDEE for Meal Planning: Use your TDEE as a target for daily calorie intake when meal planning. Plan meals that total approximately your TDEE for weight maintenance, or adjust for weight loss/gain goals. Consider macronutrient balance (protein, carbs, fats) in addition to total calories for optimal nutrition and health.

• Consider Body Composition Goals: If you want to build muscle while losing fat (body recomposition), you may need a modest calorie deficit (200-300 calories below TDEE) rather than a large deficit. Combine with adequate protein (0.8-1.2g per pound of body weight) and strength training. This is more challenging than focusing on one goal, but possible, especially for beginners or those with higher body fat.

• Factor in Non-Exercise Activity: The activity multipliers account for exercise, but non-exercise activity (walking, standing, fidgeting) also burns calories. If you have a very active job or lifestyle (e.g., construction worker, nurse), you may need to select a higher activity level or add extra calories to account for non-exercise activity.

• Increase Muscle Mass to Boost BMR: Muscle burns more calories at rest than fat, so increasing muscle mass through strength training can boost your BMR over time. While the increase may be modest (50-100 calories per day), it adds up over time and helps with long-term weight management. Combine strength training with adequate protein intake to build and maintain muscle.

• Consult Professionals for Special Situations: If you have medical conditions, are pregnant, breastfeeding, are an athlete, have an eating disorder, or are under 18 or over 80, consult registered dietitians or healthcare professionals for personalized guidance. Standard BMR/TDEE equations may not be appropriate for these situations, and professional guidance ensures safe and effective nutrition planning.

BMR/TDEE Benchmarks: Understanding Typical Ranges

While BMR and TDEE vary by individual, here are general benchmarks to help you understand typical ranges:

Age/Sex	Typical BMR Range	TDEE (Moderate Activity)	TDEE (Very Active)
25-year-old Female	1,300-1,500 kcal	2,015-2,325 kcal	2,243-2,588 kcal
25-year-old Male	1,600-1,800 kcal	2,480-2,790 kcal	2,760-3,105 kcal
40-year-old Female	1,250-1,450 kcal	1,938-2,248 kcal	2,156-2,503 kcal
40-year-old Male	1,550-1,750 kcal	2,403-2,713 kcal	2,674-3,019 kcal
60-year-old Female	1,200-1,400 kcal	1,860-2,170 kcal	2,070-2,415 kcal
60-year-old Male	1,500-1,700 kcal	2,325-2,635 kcal	2,588-2,933 kcal

Key Insight: BMR decreases with age due to muscle loss and metabolic changes, while TDEE varies significantly by activity level. A 25-year-old woman with BMR 1,400 kcal has TDEE 2,170 kcal (Moderate) or 2,415 kcal (Very Active). The same person at age 60 might have BMR 1,300 kcal and TDEE 2,015 kcal (Moderate) or 2,245 kcal (Very Active). Activity level has a major impact on TDEE, so increasing activity can significantly increase calorie needs.

Limitations & Assumptions: What This Calculator Doesn't Include

This calculator uses simplified assumptions to estimate BMR and TDEE. It does not account for many real-world complexities:

• BMR and TDEE Are Estimates, Not Exact Numbers: The calculator uses the Mifflin-St Jeor equation, which is considered accurate but still provides estimates. Your actual BMR and TDEE may be 10-15% higher or lower than calculated due to individual factors like muscle mass, genetics, medical conditions, and more. The calculator provides rough estimates, not guarantees.

• Activity Multipliers Are Broad Categories: The activity level multipliers (1.2x to 1.9x) are broad estimates that may not perfectly match your actual activity. Your actual activity may fall between categories, or you may have non-exercise activity (e.g., very active job) that isn't fully captured. The multipliers are approximations, not exact measurements.

• Doesn't Account for Muscle Mass: The calculator uses weight, but doesn't distinguish between muscle and fat. Two people with the same weight but different body compositions (one muscular, one with high body fat) will have different BMRs. Muscle burns more calories at rest than fat, so muscular people may have higher BMR than calculated. The calculator doesn't account for body composition.

• Doesn't Account for Medical Conditions: The calculator doesn't consider medical conditions that affect metabolism, such as thyroid disorders, diabetes, hormonal imbalances, or other conditions. These conditions can significantly increase or decrease actual calorie needs. If you have medical conditions, consult healthcare professionals for personalized guidance.

• Not Appropriate for Pregnancy or Breastfeeding: Standard BMR/TDEE equations are not designed for pregnancy or breastfeeding, which significantly increase calorie needs (typically 300-500+ calories per day). The calculator doesn't account for these situations. If you're pregnant or breastfeeding, consult healthcare professionals for appropriate calorie targets.

• Doesn't Account for Medications: Some medications can increase or decrease metabolism, appetite, or calorie absorption. The calculator doesn't consider medications. If you're taking medications that affect metabolism, consult healthcare professionals for personalized guidance.

• May Not Be Accurate for Athletes: High-performance athletes may have specialized fueling needs that go beyond standard TDEE calculations. Athletes may need more calories, different macronutrient ratios, or specific meal timing. The calculator provides general estimates, but athletes may need professional guidance for optimal performance.

• Doesn't Account for Adaptive Thermogenesis: Your body may adjust its metabolism in response to prolonged calorie restriction or surplus (adaptive thermogenesis). If you've been dieting for a long time, your actual BMR may be lower than calculated. The calculator doesn't account for metabolic adaptation.

Important Note: This calculator is for educational purposes only and does not provide medical, nutrition, or fitness advice. BMR and TDEE calculations are estimates based on standard equations and may not match your individual needs. Real calorie needs involve many factors this tool doesn't model, including muscle mass, medical conditions, medications, pregnancy, breastfeeding, genetics, and metabolic adaptation. Always consult qualified registered dietitians or healthcare professionals for personalized nutrition guidance, especially if you have medical conditions, are pregnant, breastfeeding, are an athlete, or are under 18 or over 80.

Sources & References

The information in this calculator is based on established nutrition science and guidelines from authoritative health organizations. For more detailed information about BMR, TDEE, and calorie needs, please refer to these trusted sources:

National Institutes of Health (NIH): Weight Management Information – Comprehensive resources on healthy weight, metabolism, and energy balance.
Centers for Disease Control and Prevention (CDC): Healthy Weight – Guidelines on balancing calories, physical activity, and nutrition.
USDA Dietary Guidelines for Americans: DietaryGuidelines.gov – Official federal nutrition guidance including calorie recommendations.
Academy of Nutrition and Dietetics: EatRight.org – Evidence-based nutrition information from registered dietitians.

Note: This calculator uses the Mifflin-St Jeor equation, which is widely recognized in nutrition science as one of the most accurate methods for estimating BMR in adults.

Frequently Asked Questions

Common questions about BMR, TDEE, calorie needs, and how this calculator works.

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest—just to keep you alive (breathing, circulating blood, etc.). TDEE (Total Daily Energy Expenditure) is your total daily calorie burn, including BMR plus all your activity throughout the day. TDEE = BMR × activity multiplier. To maintain weight, eat approximately your TDEE. To lose weight, eat less than TDEE; to gain weight, eat more than TDEE.

How accurate are BMR and TDEE calculators?

BMR and TDEE calculators provide rough estimates, typically within 10-15% of your actual needs for most people. However, many factors can affect accuracy: muscle mass (muscle burns more calories than fat), medical conditions, medications, genetics, sleep quality, stress levels, and more. The Mifflin-St Jeor equation used here is considered one of the most accurate, but it's still an estimate. For the most accurate assessment, consider metabolic testing (indirect calorimetry) or work with a registered dietitian who can help you track and adjust based on your actual results.

Can I use these numbers as a strict meal plan?

No. These are educational estimates, not personalized meal plans. The calorie ranges shown are rough guidelines. Your actual needs may be higher or lower based on many factors. Additionally, nutrition isn't just about calories—the quality and balance of macronutrients (protein, carbs, fats), micronutrients (vitamins, minerals), fiber, and meal timing all matter for health. For a personalized meal plan, consult with a registered dietitian who can consider your medical history, food preferences, lifestyle, and goals.

Do these equations work if I am pregnant, breastfeeding, or have a medical condition?

Standard BMR/TDEE equations are not designed for pregnancy, breastfeeding, or many medical conditions. Pregnancy increases calorie needs by 300-500+ calories per day (varies by trimester). Breastfeeding adds 300-500 calories per day. Medical conditions like thyroid disorders, diabetes, heart disease, kidney disease, and others can significantly affect metabolism and require specialized nutrition guidance. If you're pregnant, breastfeeding, or have a medical condition, please consult with a registered dietitian or healthcare provider for personalized guidance.

How often should I recalculate my BMR and TDEE?

Recalculate when your weight changes significantly (10+ pounds), your activity level changes substantially, or you age (though age-related changes are gradual). If you're actively losing or gaining weight, you may want to recalculate every 10-20 pounds, as your BMR will decrease as you lose weight (smaller body = lower BMR) or increase as you gain weight. However, if you're building muscle while losing fat, your BMR might stay relatively stable or even increase slightly.

Why is my calculated BMR lower than I expected?

BMR represents only the calories needed for basic bodily functions at rest—it doesn't include any activity. Many people are surprised that BMR is lower than they thought because they're used to thinking about total daily calorie needs (TDEE). Your TDEE, which includes activity, will be higher. Also, BMR naturally decreases with age and if you have lower muscle mass. If your BMR seems unusually low, double-check your height, weight, and age inputs. If accurate, consider that muscle mass affects BMR—strength training can help increase muscle mass and boost BMR over time.

What if my activity level doesn't fit the categories?

The activity level categories are broad estimates. If you're between categories (e.g., you exercise 4 days/week, which is between 'moderate' and 'active'), you can: (1) Choose the category that best fits your overall lifestyle, (2) Use the lower category for a conservative estimate, or (3) Average the multipliers (e.g., if between moderate 1.55 and active 1.725, use ~1.64). Remember, these are estimates—track your actual food intake and weight changes to see if you need to adjust. Many people find they need to fine-tune based on real-world results.

Is it safe to eat below 1200 calories per day?

For most adults, eating below 1200 calories per day is not recommended without medical supervision. Very low calorie intakes can lead to: nutrient deficiencies, muscle loss (not just fat loss), slowed metabolism, fatigue, dizziness, hair loss, and other health issues. The calculator warns if your gentle weight loss range falls below 1200 kcal/day. If you need to lose weight and your TDEE is already low, consider: (1) Increasing activity to raise your TDEE, (2) Aiming for a smaller deficit (e.g., 200-300 calories instead of 500), or (3) Working with a registered dietitian to create a safe, sustainable plan. Children, teens, and some adults may need higher minimums.

Can I build muscle while losing fat?

Yes, it's possible, especially for beginners, people returning to exercise after a break, or those with higher body fat percentages. This typically requires: (1) A modest calorie deficit (not too aggressive), (2) Adequate protein intake (often 0.8-1.2g per pound of body weight), (3) Strength training to stimulate muscle growth, and (4) Sufficient sleep and recovery. However, it's more challenging than either goal alone. Most people find it easier to focus on one goal at a time: either building muscle in a slight surplus or losing fat in a deficit. A registered dietitian or certified personal trainer can help you design a plan for body recomposition.

Why aren't my results matching what the calculator predicted?

Many factors can cause actual results to differ from calculator estimates: (1) Inaccurate food tracking (underestimating portions is common), (2) Metabolic adaptation (your body may adjust its metabolism in response to diet changes), (3) Water weight fluctuations (can mask fat loss/gain), (4) Changes in muscle mass (affects weight but not necessarily body composition), (5) Medical conditions or medications affecting metabolism, (6) Inaccurate activity level selection, or (7) The calculator is just an estimate. If you're not seeing expected results after 2-4 weeks of consistent tracking, consider: adjusting your calorie target, reassessing your activity level, or consulting with a professional to identify other factors.

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