The Core Components of MyFitnessPal's Calculation
MyFitnessPal's calorie calculation is a multi-step process that uses established metabolic science to provide a personalized, estimated daily target. The process involves calculating your Basal Metabolic Rate (BMR), determining your Total Daily Energy Expenditure (TDEE), and adjusting for your specific weight goal.
Step 1: Calculating Your Basal Metabolic Rate (BMR)
Basal Metabolic Rate (BMR) is the calories your body burns at rest for basic functions. MyFitnessPal uses the Mifflin-St Jeor equation, a widely accepted formula for BMR. The equations are:
- For Men: $BMR = (10 \times \text{weight in kg}) + (6.25 \times \text{height in cm}) - (5 \times \text{age in years}) + 5$
- For Women: $BMR = (10 \times \text{weight in kg}) + (6.25 \times \text{height in cm}) - (5 \times \text{age in years}) - 161$
Step 2: Determining Your Total Daily Energy Expenditure (TDEE)
TDEE estimates total daily calories burned, including resting metabolism and physical activity. MyFitnessPal applies an activity multiplier, based on your selected activity level, to your BMR. Common multipliers include:
- Sedentary: BMR x 1.2
- Lightly Active: BMR x 1.375
- Moderately Active: BMR x 1.55
- Very Active: BMR x 1.725
- Extra Active: BMR x 1.9
Step 3: Adjusting for Your Weight Goal
MyFitnessPal modifies your TDEE based on your weight goal. To lose one pound a week, for example, the app typically creates a 500-calorie daily deficit, as 3,500 calories approximates one pound of fat. This adjustment results in your final daily calorie target.
How the MyFitnessPal Formula Stacks Up
The Mifflin-St Jeor formula is considered reliable, but all online calculators provide estimates. Factors like body composition, genetics, and hormones can affect metabolic rate and are not fully accounted for in simple equations.
Comparison Table: Mifflin-St Jeor vs. Harris-Benedict Equation
| Feature | Mifflin-St Jeor Equation (Used by MFP) | Harris-Benedict Equation (Older Method) |
|---|---|---|
| Development Year | 1990 | 1919 (Revised in 1984) |
| Accuracy | Generally considered more accurate for modern lifestyles. | Can be less accurate, especially for obese individuals. |
| Core Formula | $BMR = 10w + 6.25h - 5a + s$ | Older formulas |
| Variables | Weight, Height, Age, Gender | Weight, Height, Age, Gender |
| Use Case | Standard for most health apps today. | An older formula often superseded. |
The Role of User Input in the Calculation
Accurate user input is vital. Logging exercise increases your calorie budget, though these estimates can also be inaccurate. The large database of user-submitted foods may contain errors, so verifying entries is advisable. Treat MyFitnessPal as a guide and adjust based on your progress.
Conclusion
MyFitnessPal's calorie calculation primarily uses the Mifflin-St Jeor equation to estimate daily energy needs. It combines personal data (age, height, weight, gender) for BMR, adjusts for activity for TDEE, and sets a goal based on weight objectives. This method is a standard, but it's an estimate. Consistent tracking and adjustments based on results are key. For more on metabolic calculations, consult resources like the National Institutes of Health.
Note: MyFitnessPal Premium may offer features influencing calculations, but the core BMR formula remains consistent.
What formula does MyFitnessPal use to calculate calories?
- Mifflin-St Jeor Equation: Used for Basal Metabolic Rate (BMR).
- Activity Multiplier: Adjusts BMR for activity to get Total Daily Energy Expenditure (TDEE).
- Weight Goal Adjustment: Modifies TDEE for weight loss or gain.
- User Input: Accuracy depends on provided age, weight, height, gender, and activity.
- Exercise Adjustment: Adds logged exercise calories to the budget.
- Estimated Numbers: All calculations are estimates.
- Premium Options: Advanced features may be available, but the core equation is the same.
