This article walks you through how CalPal AI calculates daily calorie needs, sets safe and effective targets for your goals, and helps you choose the macronutrient plan that works best for you. Along the way, you’ll also find educational resources and advanced nutrition concepts—so you can understand not just what to do, but why it works.

1. How do you calculate daily calorie needs?

To provide a personalized calculation of daily calorie target needs (Total Daily Energy Expenditure - TDEE), the app first estimates the total number of calories a user burns per day (TDEE). This is a multi-step process using widely accepted formulas.

1.1 Resting Energy Expenditure (REE)

The foundational component of our calculation is REE, which represents the calories your body burns performing basic life-sustaining functions. Our app uses the Mifflin-St Jeor equation, which is widely regarded as one of the most accurate predictive formulas.

1.2 Total Daily Energy Expenditure (TDEE)

To estimate your total daily calorie needs, REE is multiplied by a Physical Activity Level (PAL) coefficient. Our app uses standard PAL categories based on definitions from the Institute of Medicine.

The resulting TDEE serves as the baseline for your daily maintenance calories.

2. How do you calculate caloric targets for weight goals?

The app adjusts your TDEE based on your chosen weight goal. This is based on the scientific estimate that a net change of approximately 7,700 kcal is equivalent to 1 kilogram of body fat.

2.1 For Weight Loss (Caloric Deficit)

To support weight loss, the app applies a daily caloric deficit. The default setting aligns with major clinical guidelines, which recommend a deficit of 500–750 kcal per day for safe and sustainable weight management.

2.2 For Weight Gain (Caloric Surplus)

To support weight gain, the app applies a modest daily caloric surplus. The default setting aligns with sports nutrition literature, which suggests a surplus of 250–500 kcal per day to fuel tissue growth while minimizing fat accumulation.

2.3 Safety Thresholds

To ensure user safety, the app enforces minimum calorie thresholds. Calorie goals will not be set below 1,200 kcal for women or 1,500 kcal for men. These hard limits are based on public health guidelines to prevent the risks associated with very-low-calorie diets, which require medical supervision.

3. User-Selected Macronutrient Plans

Once your daily calorie goal is established, CalPal AI provides several macronutrient plans based on common, balanced eating styles. You are free to select the plan you prefer, or set your own custom goals. The percentages below are applied to your daily calorie goal to determine your final gram targets for protein, carbohydrates, and fat.

3.1 Pre-defined Macronutrient Plans

• Balanced (Default): Carbohydrates: 50%, Protein: 20%, Fat: 30%
• Low Carb: Carbohydrates: 45%, Protein: 20%, Fat: 35%
• Low Fat: Carbohydrates: 55%, Protein: 20%, Fat: 25%

3.2 Custom Plan

You always have the option to set your own custom macronutrient targets in either percentages or grams, giving you full control over your nutrition plan.

3.3 The Role of the AMDRs

All of our pre-defined plans are designed to fit within the Acceptable Macronutrient Distribution Ranges (AMDRs) established by the Institute of Medicine. These ranges are associated with reduced risk of chronic diseases while providing adequate essential nutrients.

4. Educational Resources & Advanced Concepts

For users who wish to learn more and customize their plan further, CalPal AI provides educational content based on the latest science. These advanced concepts are provided for informational purposes to help you make more informed decisions.

4.1 Advanced Topic: Protein Optimization for Specific Goals

• For Weight Loss: Clinical research suggests that a protein intake of 1.2–1.6 g/kg of body weight can enhance feelings of fullness and help preserve muscle mass during a calorie deficit.
• For Muscle Gain: The International Society of Sports Nutrition recommends a protein intake of 1.4–2.0 g/kg of body weight for exercising individuals looking to optimize muscle growth.

Users interested in applying these advanced principles can use our Custom plan feature to manually set their protein target in grams.

References

• [1] Mifflin, M. D., St Jeor, S. T., et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241–247.
• [2] Institute of Medicine. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. The National Academies Press, Washington, D.C.
• [3] Wishnofsky, M. (1958). Caloric Equivalents of Gained or Lost Weight. The American Journal of Clinical Nutrition, 6(5), 542–546.
• [4] Hall, K. D., et al. (2011). Quantification of the effect of energy imbalance on body weight. The Lancet, 378(9793), 826-837. .
• [5] Jensen, M. D., Ryan, D. H., et al. (2014). 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Circulation, 129(25_suppl_2), S102-S138.
• [6] National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (2017). Prescription Medications to Treat Overweight & Obesity. NIH Publication No. 17-4191.
• [7] U.S. Department of Agriculture & U.S. Department of Health and Human Services. (2020). Dietary Guidelines for Americans, 2020-2025 (9th ed.). https://www.dietaryguidelines.gov/
• [8] Leidy, H. J., Clifton, P. M., et al. (2015). The role of protein in weight loss and maintenance. The American Journal of Clinical Nutrition, 101(6), 1320S–1329S.
• [9] Jäger, R., Kerksick, C. M., et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14(1), 20.
• [10] Slater, G. J., Dieter, B. P., Marsh, D. J., Helms, E. R., Shaw, G., & Iraki, J. (2019). Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training. Frontiers in Nutrition, 6, 131.