For decades, the fitness and bodybuilding communities have operated under a rigid set of assumptions regarding body composition. Among experienced lifters, the holy grail of fitness—simultaneously building muscle while losing fat, commonly known as "body recomposition" or "recomping"—has long been dismissed as an urban legend. Traditional fitness lore dictated that this dual physiological feat was reserved strictly for absolute beginners experiencing novice gains or individuals utilizing anabolic steroids. Once a lifter crossed the threshold into intermediate or advanced status, conventional wisdom insisted they had to choose a lane: commit to a caloric surplus to build muscle while accepting inevitable fat gain, or enter a caloric deficit to shed fat while risking muscle loss.
However, a closer examination of scientific literature suggests that the physiological reality is far more nuanced than gym mythology implies. When researchers dig into the data, the absolute binary of bulking and cutting begins to dissolve, offering a more flexible framework for athletes and everyday gym-goers alike.
Challenging the Surplus Paradigm
To understand why body recomposition is so often written off, one must look at the prevailing theories surrounding hypertrophy. Several scientific studies over the years have directly compared resistance training outcomes in subjects consuming a caloric surplus versus those eating at maintenance levels. Generally speaking, these studies have shown that operating in a caloric surplus produces similar or slightly greater gains in raw muscle size.
The rationale behind this observation is intuitive and rooted in basic energy dynamics. Providing the body with extra energy can theoretically facilitate faster recovery, speed up glycogen replenishment, and allow individuals to train harder or maintain a higher overall training volume. All of these factors are known to support muscle hypertrophy.
Yet, when researchers look closer, the actual difference in muscle growth between a mild surplus and maintenance is often smaller than many trainers assume. Furthermore, a significant portion of the improvements measured in these studies involves indirect metrics of hypertrophy, such as increases in lean body mass. These indirect metrics can easily be swayed simply by the fluid retention and metabolic shifts associated with being in a caloric surplus, rather than representing true, unadulterated muscle fiber growth.
It is undeniably clear that people can build muscle in a surplus, but that does not preclude growth at maintenance. In a comprehensive meta-regression analyzing 52 training studies, researcher Murphy and colleagues found that while operating in a caloric deficit clearly impairs muscle gain, the majority of study participants who trained while eating around maintenance still successfully increased their lean mass.
In fact, across hundreds of independent resistance-training studies, participants are rarely given strict dietary prescriptions. Instead, they are simply instructed to maintain their usual, habitual diets while undergoing a new training regimen. Across these cohorts, bodyweight typically remains stable throughout the intervention, yet those exact same studies almost universally report simultaneous increases in muscle size and reductions in fat mass. While a caloric surplus might marginally optimize outcomes in specific contexts, the evidence confirms that body recomposition routinely occurs under maintenance conditions.
The Surprising Energetic Math of Muscle Growth
One of the most persistent misconceptions fueling the preference for bulking is the belief that the biological process of synthesizing new muscle tissue consumes a massive amount of energy. The intuitive leap is that because muscle is metabolically active tissue, building it requires a substantial surplus of dietary calories to fuel the construction process.
However, physiological science tells a different story. A comprehensive review by Slater and colleagues calculated the actual metabolic cost of building skeletal muscle mass to be roughly between 12.7 and 19.5 kilojoules per gram of tissue. When converted, this equals a modest 3 to 4.6 kilocalories per gram of actual muscle mass synthesized.
To put this in perspective, one must also factor in the inherent energy density of the muscle tissue itself, with most scientific estimates placing this value at around 16.7 kilojoules per gram of protein.
Consider the trajectory of an average intermediate lifter. Under favorable conditions, an intermediate might realistically hope to gain roughly two to four pounds of pure muscle tissue over the course of an entire year. When applying the energetic cost figures provided by researchers, the total energy required to deposit that amount of muscle mass equates to roughly 3,450 to 9,800 kilocalories spread out over 365 days.
When that figure is broken down to a daily scale, the math reveals a striking reality: the biological process of building muscle requires an extra 9 to 27 kilocalories per day.
This minuscule requirement is noteworthy for three fundamental reasons. First, an extra 9 to 27 calories per day is an infinitesimally small number in the context of human nutrition. Second, attempting to consume a caloric surplus of that exact magnitude is practically impossible in the real world. Commercial food labels naturally vary by several percent even under tightly controlled manufacturing conditions, and estimating caloric intake from mixed, everyday meals introduces margins of error that completely dwarf a 20-calorie variance. Third, that tiny energetic requirement can almost certainly be met endogenously by the body mobilizing a negligible amount of stored energy from internal glycogen stores or adipose tissue.
In short, the actual chemical synthesis of new muscle tissue does not demand a measurable dietary surplus on a day-to-day basis.
Viewing Energy Balance as a Continuum
Rather than categorizing nutrition into rigid, isolated modes like cutting, recomping, and bulking, researchers and sports scientists suggest it is far more accurate to view energy balance as a continuous spectrum.
Operating in a clear caloric deficit maximizes fat loss, but it invariably tends to limit or slightly reverse the body’s capacity for hypertrophy. Eating strictly at maintenance allows for simultaneous, moderate fat loss and moderate muscle gain. Conversely, shooting for a deliberate caloric surplus maximizes the rate of hypertrophy, but it comes at the predictable cost of accumulating some degree of stored body fat.
Where an individual falls on this energetic continuum depends heavily on their training quality, systemic recovery, and current baseline body composition. Someone carrying a higher percentage of body fat naturally possesses a greater reservoir of stored energy to draw from, which makes the physiological mechanics of body recomposition significantly easier to execute. On the other end of the spectrum, someone who is already exceptionally lean may struggle to stimulate new growth without the permissive environment of a true caloric surplus.
Accounting for Training Status and Physiological Boundaries
While the science supports the feasibility of recomposition, researchers note several important caveats and limitations regarding who can achieve it and when.
The vast majority of studies investigating body composition changes involve relatively untrained or intermediate-level lifters. As an individual progresses into advanced training status, the total rate of muscle gain slows down dramatically. This natural deceleration makes body recomposition a slower process, but it does not render it impossible. In practical terms, both traditional bulking and body recomposition yield smaller, more incremental returns for advanced athletes. The primary difference lies in the pacing and timeline of the results rather than their fundamental feasibility.
Furthermore, there are clear physiological boundaries governing when recomposition remains an effective strategy. At extremely low body fat levels, maintaining strict calorie balance can impose a ceiling on further growth. Conversely, individuals carrying a moderate amount of excess body fat have ample internal energy reserves to pull from to fuel training adaptations. If an individual is well below their natural physiological settling point, achieving recomposition becomes considerably more difficult. However, if they are near or above that settling point, the body adapts remarkably well to maintenance conditions.
Ultimately, current research and real-world observation confirm that body recomposition is far from a myth. While the magnitude of change may be modest, particularly for advanced lifters, it occurs regularly.
Engaging in a dedicated bulking phase still makes practical sense for individuals who are relatively lean and comfortable accepting some fat gain in exchange for the fastest possible muscle acquisition. However, for those who are already close to their long-term target weight or who simply prefer a steadier, leaner approach to physical development, staying near maintenance while prioritizing progressive, high-quality training can yield an optimal balance between strength gains, muscle retention, and physical aesthetics.
