Macros that protect muscle in a deficit
When you eat fewer calories than you burn, your body can pull energy from muscle as well as fat. A high-protein diet is the simplest way to tilt that balance toward fat. The evidence for dieting athletes, summarized by Helms, Aragon, and Fitschen in the Journal of the International Society of Sports Nutrition (2014), puts the useful range at about 1.8 to 2.2 grams of protein per kilogram of body weight. This calculator sets protein at 2.0 grams per kilogram and builds the rest of the day around it.
How this calculator builds your cut
- Estimate maintenance calories from your TDEE, using Mifflin-St Jeor for resting metabolism and an activity multiplier.
- Subtract your chosen deficit: 250, 500, or 750 calories a day.
- Set protein at 2.0 grams per kilogram of body weight.
- Put a quarter of calories toward fat, then fill the rest with carbohydrate.
The target never drops below 1,200 calories a day. If your deficit would take it lower, the calculator holds the floor and tells you.
Choosing your deficit
A kilogram of body fat stores roughly 7,700 calories, so a 500-calorie daily deficit adds up to about half a kilogram, or one pound, a week. A milder 250-calorie cut loses at half that pace and is easier to sustain; an aggressive 750-calorie cut is faster but harder on energy, training, and muscle. Pick the rate you can hold for months, not the fastest one. The macro calculator covers goals beyond weight loss, including maintenance and lean gains.
When to ease off
Fast weight loss is not a sign the plan is working better. Very low calorie intake brings fatigue, muscle loss, and hunger that ends most diets early, which is why the target here is floored at 1,200 calories. These numbers are estimates for healthy adults and are not medical advice; if you have a health condition or take regular medication, check with your doctor before starting a deficit. For a very low-carb version of the same cut, the keto macro calculator uses fat as the balance instead.
