Common questions about calorie calculation, BMR, TDEE, and the Mifflin-St Jeor equation. For more detailed information, visit our nutrition blog.
How accurate is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation is considered one of the most accurate BMR calculation formulas, with an accuracy rate of approximately 70-80%. It's widely used by dietitians and nutritionists. However, individual metabolism can vary based on muscle mass, body composition, genetics, and health conditions, so results should be used as a starting point.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at rest to maintain basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by your activity level, representing the total calories you burn in a day including all physical activity. TDEE is what you need to know to maintain, lose, or gain weight.
How many calories should I eat to lose weight?
To lose weight, you need to create a calorie deficit. A safe rate is 0.5-1 kg per week. For 0.5 kg/week weight loss, subtract 550 calories from your TDEE. For 1 kg/week, subtract 1100 calories. However, never go below 1200 calories (women) or 1500 calories (men) without medical supervision. Consult a registered dietitian for personalized guidance. For comprehensive weight loss support, explore our
weight loss nutrition services.
How often should I recalculate my calorie needs?
Recalculate your calorie needs when: your weight changes by 5-10 kg, your activity level changes significantly, you reach a plateau in weight loss/gain, or every 3-6 months as your body composition changes. Your calorie needs decrease as you lose weight, so regular recalculation is important for continued progress.
Can I use this calculator during pregnancy?
This calculator provides general calorie estimates but may not be accurate during pregnancy as calorie needs change significantly. Pregnant women need additional calories, typically 300-500 extra calories per day in the second and third trimesters. Always consult with a registered dietitian or healthcare provider for personalized pregnancy nutrition guidance. Learn more about our
pregnancy and fertility nutrition services.
What is the Mifflin-St Jeor equation formula?
The Mifflin-St Jeor equation is a mathematical formula used to estimate Basal Metabolic Rate (BMR). For men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161. This equation was developed in 1990 and is considered more accurate than older formulas like Harris-Benedict.
How accurate is calorie calculation for weight loss?
Calorie calculations using the Mifflin-St Jeor equation have approximately 70-80% accuracy for weight loss planning. However, individual results vary based on metabolism, muscle mass, body composition, and lifestyle factors. The best approach is to use calculated values as a starting point and adjust based on your actual weight changes over 2-4 weeks. Tracking progress and making adjustments is key to successful weight loss.
Can I use this calculator if I'm pregnant or breastfeeding?
This calculator provides general calorie estimates, but calorie needs change significantly during pregnancy and breastfeeding. Pregnant women need extra calories, typically 300-500 extra calories per day in the second and third trimesters. Breastfeeding mothers need approximately 500 extra calories per day. For personalized pregnancy or breastfeeding nutrition guidance, always consult a registered dietitian or healthcare provider. Learn more about our
pregnancy and fertility nutrition services.
What's the difference between BMR and resting metabolic rate (RMR)?
BMR (Basal Metabolic Rate) is measured under strict conditions after 8 hours of sleep and 12 hours of fasting, requiring complete rest. RMR (Resting Metabolic Rate) is measured under less strict conditions and is typically about 10% higher than BMR. Both represent calories burned at rest, but BMR is more precise. For practical purposes, most calculators use BMR formulas that actually estimate RMR values.
How do I know which activity level to choose?
Choose your activity level based on your weekly exercise routine: Sedentary (little or no exercise) = 1.2, Lightly active (light exercise 1-3 days/week) = 1.375, Moderately active (moderate exercise 3-5 days/week) = 1.55, Very active (hard exercise 6-7 days/week) = 1.725, Extra active (very hard exercise, physical job) = 1.9. If you're unsure, start with a lower level and adjust based on your results after 2-3 weeks.
Can metabolism affect my calorie needs?
Yes, metabolism significantly affects calorie needs. Factors like age (metabolism slows 2-3% per decade after 20), gender (men typically have higher metabolism), muscle mass (more muscle increases metabolism), genetics, thyroid function, and medical conditions can all impact your metabolic rate. The calculator provides estimates based on average metabolism, but individual variations are normal.
What if my calculated calories seem too low or too high?
If calculated calories seem too low (below 1200 for women or 1500 for men for weight loss), consult a healthcare provider. If they seem too high, verify your activity level selection. Remember that calculators provide estimates, and individual needs vary. Start with the calculated values, track your progress for 2-3 weeks, and adjust by 100-200 calories based on actual results. A registered dietitian can help personalize your calorie goals.
Should I track macros or just calories?
For most people, tracking calories is sufficient for weight management. However, tracking macronutrients (protein, carbohydrates, and fats) can be beneficial for muscle building, athletic performance, or specific dietary goals. Our calculator provides macro breakdowns based on standard ratios (30% protein, 40% carbs, 30% fat). For optimal results, consider tracking both calories and macros, especially if you have performance or body composition goals. Athletes and active individuals may benefit from our
sports nutrition services for specialized guidance.
Can medical conditions affect my calorie requirements?
Yes, medical conditions like diabetes, thyroid disorders, PCOS, metabolic syndrome, digestive disorders, and certain medications can significantly affect calorie requirements and metabolism. This calculator provides general estimates and may not be appropriate for individuals with certain medical conditions. Always consult with a healthcare provider or registered dietitian if you have a medical condition that affects metabolism or nutrient absorption. Our
disease-specific nutrition therapy services can provide personalized guidance for medical conditions.
