Body Recomposition Calculator
Calculate your exact training day vs. rest day calories and protein targets to build lean muscle mass while losing body fat simultaneously.
High energy mobilization from fat stores allows simultaneous rapid fat loss and muscle gain without needing caloric surpluses.
The Science of Body Recomposition: Gaining Muscle While Losing Fat
Body recomposition (simultaneously increasing skeletal muscle mass while reducing adipose tissue) was long thought to be biologically impossible because hypertrophy requires energy while fat loss requires an energy deficit. However, peer-reviewed sports nutrition literature (such as Barakat et al., 2020) proves that stored body fat provides the necessary endogenous energy to fuel muscle protein synthesis (MPS) when protein intake is sufficiently high.
Who Can Successfully Recomp?
- Beginners / Untrained Individuals: Experience rapid neuromuscular and hypertrophic adaptations ("newbie gains") even in a moderate caloric deficit.
- Overfat / High Body Fat Individuals: Massive internal energy stores easily mobilize to fuel muscle protein synthesis.
- Detrained Lifters: Benefit from "muscle memory" (retained myonuclei in skeletal muscle cells allowing rapid regrowth).
- Trained Lifters on Caloric Cycling: Advanced athletes can recomp by eating at a slight caloric surplus (+5%) on workout days and a moderate deficit (-15%) on rest days.
Protein Intake: The Non-Negotiable Pillar
During a body recomposition, the body requires higher protein than during a traditional bulk. Clinical consensus recommends 2.2g to 2.6g per kilogram of Fat-Free Mass (1.0 to 1.2g per pound) to maximize muscle protein synthesis and prevent catabolism on deficit rest days.
Reviewed against peer-reviewed primary sources by the TDEEmacro Editorial Team · Last reviewed 2026-08-24
Formulas and clinical thresholds on this page are grounded in peer-reviewed primary literature and established physiological standards. Always consult a registered dietitian or physician before changing your dietary or exercise protocol.
- Body recomposition in trained and untrained individuals Barakat C, et al. Body Recomposition: Can Trained Individuals Build Muscle and Lose Fat at the Same Time? Strength Cond J. 2020;42(5):7-21.
- High protein diets during energy restriction Longland TM, et al. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat-mass loss. Am J Clin Nutr. 2016;103(3):738-746.
Frequently Asked Questions
Can you really build muscle and lose fat at the same time?
Yes. Peer-reviewed sports science demonstrates that stored body fat provides the required energy to fuel muscle protein synthesis when daily protein intake is high (2.2-2.6g/kg FFM) and progressive resistance training is applied.
Who gets the best results from a body recomposition?
Beginners with under 1 year of training experience, individuals with body fat over 20% (males) or 28% (females), and detrained lifters returning after a hiatus achieve the fastest recomposition results.
How many calories should I eat on training days vs rest days?
Eat at a slight caloric surplus (+5%) or maintenance on workout days to maximize muscle protein synthesis, and a 15-20% deficit on rest days to mobilize stored triglycerides.