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Scooby Nutrition Calculator

Calculate your personalized daily calorie and macronutrient needs based on your goals, activity level, and body metrics using Scooby's proven approach to nutrition.

Enter your age in years
Enter your height
Enter your current weight
Estimate your body fat percentage (optional but recommended for accuracy)

How to Use This Calculator

  1. Enter your personal information: gender, age, height, and weight
  2. Select your activity level and fitness goal
  3. Adjust the body fat percentage slider if you know your percentage
  4. Click Calculate to see your personalized calorie and macronutrient targets

Formula Used

BMR (Mifflin-St Jeor Equation):

Male: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) + 5

Female: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) - 161

Where:

  • BMR = Basal Metabolic Rate (calories burned at rest)
  • TDEE = BMR × Activity Multiplier
  • Activity Multiplier: Sedentary (1.2), Light (1.375), Moderate (1.55), Active (1.725), Very Active (1.9)
  • Calorie Target = TDEE ± 500 calories (based on goal)
  • Protein = 1.0-1.5g per pound of lean body mass
  • Fat = 20-30% of total calories
  • Carbs = Remaining calories

Example Calculation

Real-World Scenario:

A 30-year-old male, 175cm tall, weighing 80kg with 20% body fat, who exercises moderately 3-5 days per week and wants to lose fat.

Given:

  • Gender = Male
  • Age = 30 years
  • Height = 175cm
  • Weight = 80kg
  • Body Fat = 20%
  • Activity Level = Moderate (multiplier: 1.55)
  • Goal = Fat Loss

Calculation:

BMR = 10 × 80 + 6.25 × 175 - 5 × 30 + 5 = 1,731 calories

TDEE = 1,731 × 1.55 = 2,683 calories

Fat Loss Target = 2,683 - 500 = 2,183 calories

Lean Body Mass = 80kg × (1 - 0.20) = 64kg

Protein = 64kg × 2.2 = 141 lbs × 1.0g/lb = 141g (564 calories)

Fat = 2,183 × 0.25 = 546 calories ÷ 9 = 61g

Result: Daily target: 2,183 calories with 141g protein, 61g fat, and 265g carbs.

Why This Calculation Matters

Practical Applications

  • Creates a sustainable nutrition plan for your goals
  • Prevents under or overeating based on your needs
  • Optimizes macronutrient ratios for better body composition
  • Provides measurable targets for tracking progress
  • Helps break through weight loss or muscle gain plateaus

Key Benefits

  • Personalized to your unique physiology and goals
  • Based on scientifically validated formulas
  • Adjusts for activity level to prevent undereating
  • Optimizes protein intake for muscle preservation
  • Balanced approach to nutrition without extreme restrictions

Common Mistakes & Tips

Many people overestimate their activity level, leading to inflated calorie targets. Be honest about your daily movement. Remember that "moderate" means consistent, structured exercise 3-5 days per week, not just occasional activity. If you have a desk job and work out 3 times a week, you're likely in the "Light" category, not "Moderate."

Most people underestimate their body fat percentage, which leads to overestimating protein needs. If you don't have an accurate measurement, it's better to overestimate your body fat slightly or use standard averages based on your appearance. For men, average is typically 18-24%, and for women, 25-31%.

Your calorie needs change as your weight and body composition change. Recalculate your needs every 4-6 weeks or after losing/gaining 5-10 pounds. If you're not seeing progress after 2 weeks, reassess your activity level and calorie tracking accuracy before making drastic changes to your intake.

Frequently Asked Questions

This calculator uses the Mifflin-St Jeor equation, which is considered one of the most accurate formulas for calculating BMR. However, all formulas provide estimates, not exact values. Individual variations in metabolism, genetics, and other factors can affect your actual calorie needs by 10-15%. Use this as a starting point and adjust based on your results.

The activity multiplier already accounts for your exercise, so you generally don't need to eat back additional calories. If you're doing significantly more exercise than normal, you might need a small adjustment, but most people overestimate calorie burn during exercise. For best results, stick to your calculated targets and adjust based on weekly progress rather than daily fluctuations.

For fat loss, a safe and sustainable rate is 0.5-1kg (1-2lbs) per week. For muscle gain, expect 0.25-0.5kg (0.5-1lb) per month. You may see faster initial changes due to water weight, especially when reducing carbohydrates. Consistency is key - it typically takes 4-6 weeks to establish a clear trend and 8-12 weeks for significant visible changes.

No, calorie counting is a learning tool, not a lifelong requirement. Most people benefit from tracking for 4-12 weeks to understand portion sizes and food composition. After that, you can transition to more intuitive eating while maintaining awareness of your targets. Some people prefer periodic tracking (a few days each month) to stay on track without the daily commitment.

References & Disclaimer

Nutrition & Health Disclaimer

This calculator provides estimates based on established formulas and should not replace professional medical or nutritional advice. Individual nutritional needs may vary based on health conditions, medications, and other factors. Consult with a healthcare provider or registered dietitian before making significant changes to your diet, especially if you have any underlying health conditions.

References

Accuracy Notice

This calculator provides estimates based on population averages and scientific formulas. Individual metabolic variations, genetic factors, and health conditions can affect your actual energy needs by up to 15-20%. For the most accurate assessment, consider indirect calorimetry testing or consultation with a registered dietitian. Results should be used as a starting point and adjusted based on your individual response and progress.

About the Author

Kumaravel Madhavan

Web developer and data researcher creating accurate, easy-to-use calculators across health, finance, education, and construction and more. Works with subject-matter experts to ensure formulas meet trusted standards like WHO, NIH, and ISO.

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health nutrition-diet-planning scooby nutrition medical fitness body weight