How this macro split is worked out

Most web calculators apply a fixed percentage split (e.g. 40% carbs, 30% protein, 30% fat) regardless of your body size. That approach causes protein intake per kilogram to fall as your body weight increases — exactly when lean mass protection is most critical.

Instead, our derivation anchors protein and fat directly to your body weight:

1. Protein — Anchored to Body Weight

Protein is set at 1.6 g per kg of bodyweight for weight loss or maintenance (enough to protect lean muscle mass through a deficit) and 1.8 g per kg when eating in a surplus to support muscle tissue synthesis.

2. Fat — Anchored with Health Floor

Fat is set at 0.8 g per kg of bodyweight, with an essential-intake floor of 0.6 g per kg to safeguard hormone production and fat-soluble vitamin absorption.

3. Carbohydrate — The Flexible Remainder

Carbohydrate absorbs whatever calories remain in your daily budget after protein (4 kcal/g) and fat (9 kcal/g) are set, providing primary fuel for daily activity and workout recovery.

Sources

The same scientific references cited on the app's Sources & References screen:

Mortensen MD et al. Systematic Review of Protein Intake in Energy-Restricted Diets. Journal of Nutrition. 2018. (Supports 1.6–2.4 g/kg protein for lean mass retention during energy deficit.)
Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fibre, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington DC: National Academies Press, 2005. doi.org/10.17226/10490

Does this calculator store anything?

No. Your inputs are used to compute the result for this request and are never stored. Nothing is written to a database and no account is required. Privacy Policy

Macro Calculator