The Science Behind Our Macro Calculator
An inside look into the formulas and logic we use to calculate your perfect daily calories and macros.
At Let Him Cook, we don't believe in generic, one-size-fits-all meal plans. Our Macro Calculator is driven by clinically proven formulas, adapted to your unique daily activity and workout routine. Here is exactly how we determine your numbers.
Step 1: Your Basal Metabolic Rate (BMR)
Your BMR is the number of calories your body needs just to stay alive—to keep your heart beating and your lungs breathing—if you were resting in bed all day. We use the Mifflin-St Jeor Equation, which is widely considered the most accurate formula in modern clinical nutrition:
- For Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
- For Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Step 2: Factoring in Daily Activity
We take your BMR and multiply it by a factor that represents your base lifestyle (excluding your gym workouts). If you work an office job, this factor is around 1.2. If you work in construction, it's closer to 1.7. This gives us your base Total Daily Energy Expenditure (TDEE).
Step 3: Precisely Calculating Your Workouts
Instead of guessing how many calories you burn lifting weights or running, we use METs (Metabolic Equivalent of Task). Depending on the intensity and duration of your weekly workouts, we calculate exactly how much energy you expend during training, and smoothly distribute those calories across your entire 7-day week. This means you eat a consistent, easy-to-follow amount every day without starving on your rest days.
Step 4: The Dynamic Protein Multiplier
This is where our system shines. We don't just assign an arbitrary protein amount.
- Sedentary Baseline: We start at an optimal 1.2g of protein per kg of body weight for general health.
- Workout Scaling: As your weekly workout volume and intensity increase, your protein needs dynamically scale up to 1.6g/kg to support recovery.
- Goal Adjustments: If your goal is to lose weight, we add an extra buffer (up to 2.0g/kg) because keeping protein high is essential to spare muscle mass in a caloric deficit. If your goal is to gain muscle, we tune it perfectly for muscle protein synthesis.
Step 5: Optimized Fat Intake
Fats are dense in calories but crucial for hormonal balance. We set a baseline of 0.8g per kg of body weight, which is widely recognized as a "sweet spot" that protects hormonal health without wasting calories that could be better spent on energy-driving carbs. If your goal is aggressive weight loss, we drop this to 0.7g/kg to give you more breathing room. If you are gaining, we raise it to 0.9g/kg.
Step 6: Carbohydrates (The Remainder)
Carbs are your body's primary energy source. Once we've subtracted the calories assigned to your ideal protein and fat targets, 100% of your remaining energy budget is filled with carbohydrates. By keeping fats moderate, our system ensures you have plenty of carbs to fuel those intense workouts!
Understanding these mechanics ensures that when you see your daily macro split, you can trust it's scientifically designed specifically for you.