For decades, the fitness community has operated under a strict binary. When individuals decide to transform their physiques through resistance training, they are routinely told they must choose a path: commit to a caloric surplus to build muscle, commonly known as "bulking," or enter a caloric deficit to shed body fat, known as "cutting." The simultaneous pursuit of both goals—widely referred to as body recomposition—has long been dismissed by experienced lifters and coaches as a fitness myth. Conventional wisdom holds that "recomping" is a phenomenon exclusive to complete beginners whose unadapted nervous systems respond rapidly to any stimulus, or to those utilizing anabolic substances. Once an individual moves past the novice phase and accumulates a few years of serious training under their belt, the prevailing narrative dictates that building muscle while losing fat simultaneously becomes a physical impossibility.
However, a closer look at scientific literature suggests that this rigid framework may be fundamentally flawed. While sports science continues to examine the nuances of energy balance, accumulating research demonstrates that body recomposition is not only possible for experienced individuals, but it is also a frequent outcome in controlled training environments. The long-standing belief that the human body requires a significant, measurable caloric surplus to synthesize new muscle tissue is increasingly being challenged by recent biochemical data and comprehensive meta-analyses.
To understand why body recomposition has been so heavily stigmatized in advanced lifting circles, it is helpful to examine what the broader body of research reveals about caloric intake during resistance training. Several notable scientific investigations over the years have directly compared the effects of maintaining energy balance versus operating in a caloric surplus while participants engage in structured resistance training regimens. Generally, these studies indicate that being in a caloric surplus can produce similar or slightly greater gains in overall muscle size. The physiological rationale behind this observation is intuitive: extra dietary energy can facilitate recovery between grueling training sessions, speed up the replenishment of muscle glycogen stores, and allow athletes to train harder or maintain a higher overall training volume—all mechanisms that theoretically support muscle hypertrophy.
Even so, the practical difference between maintaining weight and consuming a mild caloric surplus is frequently narrower than many assume. Most of the relevant studies have tended to measure improvements via indirect assessments of hypertrophy, such as changes in overall lean body mass. These broad metrics can be easily swayed by the simple presence of a surplus, which naturally increases water retention, glycogen storage, and gut fill, making the absolute hypertrophic response appear larger than it might actually be.
Furthermore, data confirms that while muscle growth certainly occurs in a surplus, it is far from exclusive to that dietary state. In a comprehensive meta-regression analyzing 52 distinct training studies, researcher Murphy and colleagues observed that while operating in a caloric deficit clearly impairs the rate of muscle gain, the vast majority of participants who trained while eating around weight maintenance successfully increased their lean mass.
This trend becomes even more apparent when looking at the broader landscape of exercise science. Across hundreds of published resistance-training studies, participants are rarely given strict dietary prescriptions. Instead, researchers typically instruct subjects to maintain their usual, habitual dietary patterns while embarking on a new training program. While bodyweight across these cohorts generally remains remarkably stable over the course of the study, the investigators almost universally report a simultaneous increase in muscle size and a reduction in fat mass. While a deliberate caloric surplus may marginally enhance outcomes in certain specific scenarios, the scientific consensus strongly indicates that body recomposition routinely occurs under weight-maintenance conditions.
A major driver of the traditional "bulk or cut" mentality is the widespread misconception surrounding the energetic cost of muscle growth. Many fitness enthusiasts assume that the biological process of building skeletal muscle consumes an immense amount of energy, thereby necessitating a substantial caloric surplus to fuel the construction of new tissue.
Biochemical reviews, however, paint a very different picture. A prominent review conducted by Slater and colleagues calculated the actual metabolic cost of building skeletal muscle mass to be approximately 12.7 to 19.5 kilojoules per gram of tissue. Converted into more familiar units, this translates to roughly 3 to 4.6 kilocalories per gram of muscle mass. When accounting for the inherent energy density of skeletal muscle tissue—estimated by most scientific literature to be around 16.7 kilojoules per gram of protein—the true energetic overhead of muscle synthesis becomes remarkably modest.
Consider the trajectory of an average intermediate lifter. Under favorable circumstances, a dedicated intermediate might realistically gain between two and four pounds of actual muscle tissue over the course an entire year. Applying the energetic cost figures established by Slater and his colleagues, the total thermodynamic cost required to deposit that amount of muscle mass amounts to roughly 3,450 to 9,800 kilocalories spread out across a 365-day period. When broken down to a daily scale, this means the physiological process of building muscle requires an extra 9 to 27 kilocalories per day.
This minuscule energetic requirement carries several profound implications for nutrition and training science. First and foremost, an additional energy demand of 9 to 27 kilocalories per day is an extraordinarily small number—roughly equivalent to a single bite of food. Second, attempting to deliberately engineer a daily caloric surplus of that exact magnitude is practically impossible in the real world. Commercial food packaging labels are legally permitted to vary by several percent even under strict manufacturing regulations, and the inherent errors involved in estimating macronutrient intake across mixed daily meals completely dwarf a 20-calorie margin. Third, this tiny energetic requirement can almost certainly be met endogenously by the human body mobilizing stored internal energy reserves, such as mobilizing glycogen from the liver and skeletal muscles or drawing from small amounts of adipose tissue. In short, the physical act of synthesizing new muscle tissue does not require a measurable, conscious dietary surplus on a day-to-day basis.
Rather than viewing the traditional concepts of cutting, recomping, and bulking as rigid, mutually exclusive modes of operation, researchers suggest it is far more accurate to view them as distinct points along a continuous spectrum of energy balance.
Operating in a consistent caloric deficit maximizes the rate and magnitude of fat loss, but it inherently tends to limit, or in some cases slightly reverse, the body’s capacity for muscle hypertrophy. Eating strictly at maintenance calories occupies the middle ground, allowing for moderate fat loss and moderate muscle gain to occur simultaneously. Meanwhile, pushing into a deliberate caloric surplus maximizes the physiological environment for muscle hypertrophy, but this comes at the direct cost of incurring some degree of unwanted fat gain.
Where an individual falls along this energetic continuum depends heavily on their training quality, systemic recovery, and current body composition. Someone carrying a higher percentage of body fat naturally possesses a larger pool of stored internal energy to draw from, which makes the process of body recomposition significantly more accessible. Conversely, an individual who is already operating at an exceptionally lean body fat percentage may struggle to stimulate new muscle growth without the supportive environment of a true caloric surplus.
To be sure, researchers note several important caveats and limitations to this perspective. Training status remains a variable of interest, though its exact boundary conditions are still debated. The vast majority of studies investigating body recomposition involve relatively untrained or intermediate lifters. As an individual advances further along their training career, the total rate of natural muscle gain slows down dramatically. This deceleration means that body recomposition becomes a much slower process over time, though it does not render it impossible. In practical terms, advanced lifters experience diminishing returns whether they choose to bulk or recomp; the primary difference between the two approaches lies in the pacing of the results rather than their fundamental feasibility.
Similarly, biological boundaries exist regarding when recomposition remains an effective strategy. At extremely low levels of body fat, maintaining weight may fail to provide the hormonal environment necessary for further growth. On the other hand, individuals carrying a moderate amount of extra body fat have ample energy reserves readily available. If a person is well below their natural physiological settling point, achieving body recomp becomes significantly more challenging, whereas being near or slightly above that point makes simultaneous muscle gain and fat loss surprisingly achievable.
Ultimately, body recomposition is neither a biological impossibility nor a fitness myth. It is a documented, regular outcome observed consistently in scientific literature and real-world training practices alike. While the magnitude of these physical changes may be relatively modest—particularly for advanced athletes who have trained for years—the transformation happens nonetheless.
A dedicated bulking phase may still make practical sense for individuals who are relatively lean and comfortable with the prospect of adding some body fat in pursuit of the fastest possible muscular gains. However, for those who are already close to their long-term target weight or simply prefer a steadier, leaner approach to fitness, staying close to maintenance calories while prioritizing progressive resistance training may offer the optimal balance between strength development, muscle acquisition, and overall aesthetics.
