How this calculator chooses your split
We use a hierarchical approach that's the modern consensus among evidence-based sports nutritionists:
- Set protein in g/kg of body weight. The number depends on goal: 1.6 g/kg for maintenance, 2.2 g/kg during fat loss, 1.8 g/kg for muscle gain.
- Set fat at ~25% of calories. Lower than ~20% can suppress sex hormones (especially in lean trainees); much higher than 35% leaves too little budget for carbs.
- Fill the remainder with carbs. Carbs are the lever you adjust based on training volume and tolerance.
Why this beats “keto” or “low fat” defaults
For most goals, the evidence base supports flexible macros over rigid diet templates. Aragon & Schoenfeld (2013) and subsequent reviews repeatedly find that, with protein and total calories matched, the carb-to-fat ratio has little impact on body composition outcomes. There are exceptions: type 2 diabetes management often benefits from lower-carb approaches; some endurance athletes train better on higher carbs. The default we use here works for the majority.
How to use these numbers
- Hit protein every day. The other two are flexible; protein is the non-negotiable.
- Average over a week, not within a day. Birthday dinner Wednesday balances out by Sunday if the weekly average is on target.
- Adjust every 2 weeks based on outcomes. If weight isn't moving the direction you want after 2 stable weeks, change calories by ~150–250 and reassess.
- Track for 4 weeks, then mostly don't. The point of tracking is learning what your meals contain. Once you know, eyeball.
Fat loss specifics
We default to a 20% deficit for fat loss, which is sustainable for most people while preserving training quality and muscle. Larger deficits work short-term but the failure mode is rebound — both physiological (lower NEAT, hunger hormone changes) and behavioral (adherence breakdown). Slower is genuinely faster.
Muscle gain specifics
A 10% surplus is enough for muscle gain in nearly all trainees beyond the first 6 months. Larger surpluses produce more fat gain without more muscle gain. Past the novice phase, gain weight at ~0.5 lb/week or slower.
References
- Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr. 2013;10(1):5.
- Helms ER et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes. Int J Sport Nutr Exerc Metab. 2014;24(2):127-138.
- Schoenfeld BJ et al. Effects of supervised vs. unsupervised training programs on muscular strength and hypertrophy. J Strength Cond Res. 2019.