How this macronutrient calculator for cutting works
A cutting phase means reducing body fat while preserving as much lean muscle mass as possible. This calculator estimates your maintenance calories, applies your chosen calorie deficit, and then assigns protein, fat, and carbohydrate targets in grams.
The goal is not just “eat less.” The goal is to cut intelligently: enough energy restriction to lose fat, enough protein to retain muscle, enough fat to support hormones, and enough carbs to fuel training performance.
Calculation method
1) Maintenance calories (TDEE)
The tool estimates your BMR using one of two common methods:
- Katch-McArdle if body fat % is provided (uses lean body mass).
- Mifflin-St Jeor if body fat % is not provided.
BMR is then multiplied by your activity factor to estimate TDEE (total daily energy expenditure).
2) Apply calorie deficit
Cutting calories are calculated as: TDEE × (1 - deficit %). A moderate deficit (15-25%) is common for most people.
3) Set macros
- Protein: body weight × protein setting (default 2.2 g/kg)
- Fat: body weight × fat setting (default 0.8 g/kg)
- Carbs: remaining calories after protein and fat are set
Since protein and carbs provide 4 kcal/g and fat provides 9 kcal/g, your grams are converted from calories in the final step.
What are good macro targets for a cut?
Protein
If muscle retention is a top priority, protein is usually set high. A practical range is 1.8 to 2.6 g/kg, especially useful when body fat is lower or the deficit is more aggressive.
Fat
Dietary fat is essential for hormones, satiety, and nutrient absorption. Many people do well around 0.6 to 1.0 g/kg. Going too low for too long can reduce adherence and recovery.
Carbohydrates
Carbs are performance fuel. Once protein and fat are set, carbs get the remaining calories. If your training quality drops, consider a smaller deficit before slashing carbs too hard.
Example cutting setup
Suppose someone is 75 kg, moderately active, and chooses a 20% deficit with 2.2 g/kg protein and 0.8 g/kg fat:
- Protein = 165 g/day
- Fat = 60 g/day
- Carbs = remaining calories
This often creates a balanced plan that supports lifting while still producing steady fat loss.
Common cutting mistakes
- Using an aggressive deficit immediately (hard to sustain, higher muscle loss risk)
- Undereating protein
- Dropping fats too low
- Ignoring strength training progression
- Changing calories every day based on scale fluctuations
How to adjust after 2-3 weeks
Track average weekly weight and measurements. If progress is stalled for two consecutive weeks:
- Reduce calories by 100-200/day, or
- Increase daily steps/cardio modestly, or
- Improve consistency with logging and meal timing first
Aim for a sustainable pace. Roughly 0.3% to 0.8% body weight loss per week is a common target depending on starting body fat.
Final notes
This macronutrient calculator for cutting provides an evidence-based starting point, not an absolute prescription. Your actual maintenance needs can vary. Use the numbers for 2-3 weeks, review real-world progress, and then adjust.
For best results: train with progressive overload, sleep 7-9 hours, keep stress under control, and stay consistent with food quality and tracking.