This article explains how CalPal AI calculates your daily calorie needs, sets safe and effective targets for your goals, and helps you choose the macronutrient plan that works best for you — so you understand not just what to do, but why it works.
This content is for informational and educational purposes only and is not medical advice. Always consult a qualified healthcare provider regarding your health objectives.
1. How daily calorie needs are calculated
To personalize your calorie target, the app first estimates your Total Daily Energy Expenditure (TDEE) — the total calories you burn per day — using widely accepted formulas.
Resting Energy Expenditure (REE)
REE is the energy your body burns performing basic life-sustaining functions. CalPal AI uses the Mifflin-St Jeor equation, one of the most accurate predictive formulas:
- Men: REE = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
- Women: REE = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
Total Daily Energy Expenditure (TDEE)
REE is then multiplied by a Physical Activity Level (PAL) coefficient, using standard categories from the Institute of Medicine:
- Sedentary: REE × 1.2
- Lightly active: REE × 1.375
- Active: REE × 1.55
- Very active: REE × 1.725
The resulting TDEE is the baseline for your daily maintenance calories.
2. Calorie targets for weight goals
The app adjusts your TDEE based on your goal, using the scientific estimate that a net change of roughly 7,700 kcal equals 1 kilogram of body fat.
Weight loss (caloric deficit)
To support weight loss, the app applies a daily deficit. The default aligns with major clinical guidelines, which recommend 500–750 kcal per day for safe, sustainable results.
Weight gain (caloric surplus)
To support weight gain, the app applies a modest surplus. The default aligns with sports nutrition literature, which suggests 250–500 kcal per day to fuel growth while minimizing fat gain.
Safety thresholds
For your safety, calorie goals are never set below 1,200 kcal for women or 1,500 kcal for men. These limits are based on public health guidelines that warn against very-low-calorie diets without medical supervision.
3. Macronutrient plans
Once your calorie goal is set, CalPal AI offers balanced macronutrient plans. You can pick one or set custom targets; the percentages apply to your daily calories to determine grams of protein, carbs, and fat.
Pre-defined plans
- Balanced (default): Carbs 50%, Protein 20%, Fat 30%
- Low carb: Carbs 45%, Protein 20%, Fat 35%
- Low fat: Carbs 55%, Protein 20%, Fat 25%
Custom plan
You can always set your own targets in percentages or grams, for full control over your nutrition.
The role of the AMDRs
All pre-defined plans fit within the Acceptable Macronutrient Distribution Ranges (AMDRs) from the Institute of Medicine, associated with reduced chronic-disease risk while providing adequate nutrients:
- Carbohydrates: 45–65%
- Protein: 10–35%
- Fat: 20–35%
4. Advanced concepts
For those who want to go further, CalPal AI provides educational content based on current science.
Protein optimization for specific goals
- For weight loss: research suggests 1.2–1.6 g/kg of body weight can improve fullness and help preserve muscle during a deficit.
- For muscle gain: the International Society of Sports Nutrition recommends 1.4–2.0 g/kg for exercising individuals optimizing muscle growth.
Use the Custom plan to set your protein target in grams and apply these principles.
References
- 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.
- Institute of Medicine. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press.
- Wishnofsky, M. (1958). Caloric equivalents of gained or lost weight. The American Journal of Clinical Nutrition, 6(5), 542–546.
- Jäger, R., Kerksick, C. M., et al. (2017). International Society of Sports Nutrition position stand: protein and exercise. JISSN, 14(1), 20.
