Is Bulking Necessary for Muscle Gain?
Table of Contents
Key Takeaways: Is Bulking Necessary for Muscle Gain?
- A deliberate calorie surplus is not a strict biological requirement for gaining muscle. Muscle and lean mass can be gained without a dedicated bulk, including at maintenance intake and, in some situations, during a calorie deficit.
- More calories do not automatically mean more muscle. Once nutritional needs are adequately covered, a larger surplus appears more likely to increase body weight and fat gain than to produce proportionally greater hypertrophy.
- Resistance training remains the primary hypertrophic stimulus. Extra energy intake does not appear to keep increasing the acute muscle-protein-synthesis response simply because more calories are consumed.
- The size of a calorie deficit matters. A deficit of around 500 kcal per day was associated with impaired lean-mass gains in a meta-regression, even though strength gains were less affected.
- Body recomposition is possible, including in trained individuals, although it may be easier in less-trained people, those returning to training, and people with more stored body fat available as an energy source.
- Protein intake and total calorie intake are separate variables. It is possible to keep protein intake high while remaining at maintenance calories or in a deficit, which can be useful when the goal is to preserve or gain lean mass while losing fat.
- For many people, bulking and cutting are better viewed as optional strategies rather than mandatory phases. A surplus may still be useful in some situations, but eating more than necessary does not appear to guarantee faster muscle growth.
Introduction: Is Bulking Necessary for Muscle Gain?
“Bulking” — deliberately eating in a calorie surplus to build muscle, usually followed by a separate “cutting” phase to lose the accompanying fat — has long been a common framework in strength-training culture. In its more extreme form, the idea is not simply that a calorie surplus may help support muscle gain, but that the more you eat while training hard, the more muscle you will build. This can lead to the assumption that meaningful muscle growth is difficult, or even hardly worth pursuing, unless you are deliberately eating above maintenance.
The other half of the traditional bulk/cut model is timing: stay in a surplus for as long as possible, then reduce body weight relatively quickly when a competition, summer, or another deadline approaches. In practice, this can create a repeated cycle of gaining weight and then dieting it back off. I have come across this mindset many times in both athletic and clinical settings, particularly in people who have started to view bulking and cutting as unavoidable parts of resistance training rather than optional strategies that may or may not fit their goals.
What concerns me most is not the idea of using a calorie surplus itself. A surplus can be a perfectly reasonable tool in the right context. The problem is the stronger assumption underneath it: that without extra calories coming in, resistance training somehow becomes much less productive, and that eating progressively more will continue to produce proportionally more muscle. That assumption can lead some people to accept more fat gain than they actually wanted, followed by a more aggressive dieting phase later.
The evidence is more nuanced than that traditional framework suggests. In this article, I look at what the literature actually shows about energy balance and muscle hypertrophy: whether a calorie surplus is truly required, what happens to muscle growth at maintenance calories or in a deficit, who may be more likely to achieve body recomposition, and whether a larger surplus actually produces more muscle rather than simply more body weight. For those who do choose to bulk, the separate question of how to do it while minimizing unnecessary fat gain is covered in muscle gain without fat gain.
What Does “Bulking” Actually Assume?
The traditional case for bulking rests on a simple energetic argument: skeletal muscle tissue is roughly 75% water and about 20% protein, so building new tissue costs energy — an observation often taken to imply that this energy must come from a deliberate dietary surplus, though whether it has to be supplied exogenously through food rather than drawn from the body’s own energy stores is treated as an open question in the underlying review [1]. Textbook guidance built on this logic has recommended surpluses ranging from roughly 1,500–2,000 kJ per day in weight-stable athletes up to an additional 4,000 kJ per day in those struggling to gain muscle [1].
The problem, according to a 2019 review dedicated specifically to whether bulking is actually necessary, is that these estimates have never been validated in a resistance-training population against an actual hypertrophy outcome [1]. They assume the energy cost of new muscle tissue is simply the sum of its parts, without accounting for the additional metabolic cost of building and remodeling that tissue, or for the body’s own adaptive response to extra calories (increased non-exercise movement, increased diet-induced thermogenesis, and so on) [1]. In other words, the “textbook surplus” was never really derived from muscle-building experiments — it was derived from theoretical bookkeeping.
Is an Energy Surplus Actually Required to Build Muscle?
The most direct answer to whether bulking is necessary comes from the same 2019 review, which concluded that no rigorously controlled study had, at that point, directly assessed whether an energy surplus is required to maximize resistance-training-induced muscle hypertrophy [1]. What data did exist pointed in a specific direction: overfeeding by itself, without a resistance-training stimulus, typically produces substantially more fat mass gain than fat-free mass gain. In a classic overfeeding study in twins, roughly 2 kg of fat mass was gained for every 1 kg of lean mass, despite a substantial and sustained calorie surplus [1].
This matters because a calorie surplus by itself is not a reliable way to preferentially build skeletal muscle; resistance training provides the primary hypertrophic stimulus, as covered in more detail in what actually causes muscle growth. Additional evidence supports the same conclusion at the level of muscle protein synthesis (MPS) itself: extra energy intake does not appear to further increase the acute MPS response to a protein-containing meal, either at rest or after a resistance-training session [1]. If a surplus doesn’t measurably enhance the acute anabolic signal on top of training and protein, it becomes harder to defend as a strict requirement for growth over time.
One way to think about this is that muscle growth appears to use the energy and nutrients it needs when they are available, but not simply keep increasing in proportion to every additional calorie consumed. In other words, once nutritional needs are adequately covered, providing progressively more energy does not automatically translate into progressively more muscle growth.
From a practical perspective, this is an important distinction. I would not interpret it as meaning that energy intake is irrelevant — adequate nutrition still matters for supporting training, recovery, and muscle accretion. But it does suggest that deliberately pushing calories far beyond what is needed may offer little additional benefit for muscle growth itself, while increasing the likelihood that more of the extra energy is stored as body fat.
There is also a psychological side to this. For some people, seeing body weight increase while strength training can feel motivating because it creates a visible sense of progress. In practice, though, scale weight does not tell us how much of that gain is actually muscle. If body weight is rising quickly, at least part of that increase may simply reflect additional fat mass rather than a proportionally greater hypertrophic response. I think this is an important distinction, because otherwise the number on the scale can easily be mistaken for evidence that the bulk itself is working particularly well.
In that sense, the goal is not necessarily to eat as much as possible, but to make sure nutritional needs are met without assuming that a larger surplus — or a faster increase in body weight — must produce more muscle.
What Happens to Muscle Growth in a Deficit or at Maintenance?
If a surplus were truly required, muscle growth should be essentially impossible without one. That is not what the literature shows.
A 2020 review dedicated to this exact question — whether trained individuals can build muscle and lose fat at the same time, a phenomenon generally referred to as body recomposition — compiled a substantial body of randomized controlled trials in resistance-trained populations demonstrating simultaneous fat-free mass gains and fat mass losses, contrary to the common assumption that this only happens in novice or overweight populations [2]. Several of the studies in that review reported no nutritional intake data at all — meaning caloric intake was neither confirmed adjusted nor confirmed unchanged — and still produced significant lean mass gains alongside fat loss [2].
Other studies in the same review deliberately increased protein intake — without necessarily creating an overall calorie surplus, or in some cases while still in a deficit — and observed body recomposition of a larger magnitude. In one trial, well-trained men and women following a high-protein diet (3.4 g/kg/day) gained a significant amount of lean mass while simultaneously losing a significant amount of fat mass [2]. In an extreme-volume resistance-training study, groups receiving graded whey protein supplementation on top of a targeted, roughly 500-calorie surplus gained fat-free mass while simultaneously losing fat mass, whereas a maltodextrin-supplemented group (with a similar total daily protein intake, not significantly different between groups) gained fat-free mass alongside a small, non-significant fat mass gain rather than a loss — a difference the review suggests may point to an effect of nutrient timing or composition beyond total calorie and protein intake, though it stops short of establishing what specifically drove it [2].
This does not mean a calorie deficit is free of cost for muscle building. A 2022 meta-analysis and meta-regression pooling randomized controlled trials of resistance training performed under energy restriction for three or more weeks found that lean mass gains were significantly impaired in a deficit compared with parallel non-deficit control groups, even though strength gains were largely preserved [3]. The meta-regression identified an energy deficit of approximately 500 kcal per day as sufficient to prevent lean mass gains from resistance training [3]. This is a related but distinct question from muscle loss during an existing deficit, which is covered in more detail in how much muscle you lose when losing weight — the relevant point here is that muscle can still be gained in a mild deficit or at maintenance, but a large, sustained deficit is a genuine obstacle to hypertrophy, separate from the question of whether a surplus is required.
The size of the calorie deficit becomes especially relevant when the goal is to lose fat while still trying to gain or preserve muscle. A deficit of around 500 kcal per day is a fairly common practical target because it often corresponds to roughly half a kilogram of weight loss per week, although the exact relationship varies between individuals.
From a clinical and practical perspective, the important point is that a deficit of this magnitude may already be large enough to meaningfully impair lean-mass gains from resistance training. That creates a real trade-off for people who want body recomposition rather than simply faster weight loss: the deficit needs to be large enough to produce fat loss, but not so aggressive that it unnecessarily limits the muscle-building response.
I also think calorie targets are often treated as more precise than they really are. In practice, estimating both energy expenditure and actual food intake is difficult, and there can be a meaningful gap between the deficit someone intends to create and the deficit they actually end up in. I have noticed this in my own experience as well: when I tried to follow a calculated calorie target, I sometimes ended up eating even less than planned. That is one reason I would interpret a prescribed deficit as an estimate rather than as an exact physiological number.
Who Benefits Most From Building Muscle Without a Surplus?
Body recomposition — building muscle and losing fat concurrently, without a dedicated bulk phase — is not equally effective for everyone. Beginners and those returning to training after time away, individuals carrying higher starting body fat, and trained individuals combining resistance training with a genuinely high protein intake are among the contexts in which body recomposition has been reported in the literature [2].
The mechanism proposed for this pattern is that higher body fat levels may provide the endogenous energy needed to help support muscle accretion even without much or any additional dietary energy, while a novel training stimulus in a less-trained individual can provide a particularly strong hypertrophic stimulus [2]. Lean, highly experienced lifters may show a smaller — though not absent — recomposition effect than less-trained or higher-body-fat individuals; direct evidence comparing how that rate stacks up against a dedicated surplus phase over the same period is limited.
Physique competitors during contest preparation are something of an exception within the trained population: most published case studies of natural bodybuilders through a competition prep phase do not show a recomposition effect, and some show lean mass loss despite high protein intake and continued resistance training [2]. This is thought to reflect the unusually extreme combination of a large, sustained energy deficit, very low body fat, high training and cardio volume, and the negative hormonal changes (including reduced testosterone) that accompany aggressive contest dieting [2] — a genuinely different situation from a typical lifter simply choosing not to run a surplus.
Body recomposition — losing fat while gaining or preserving muscle — is probably one of the most common goals among people who simply want to improve their body composition and feel that they are getting into better shape. For them, the goal is not necessarily to maximize body weight or muscle mass, but to become leaner while maintaining or gradually increasing lean mass.
A second group I am especially familiar with is weight-class athletes, including combat-sport athletes. In these sports, carrying as much useful lean mass as possible within a relatively low body weight can offer a competitive advantage. That creates a different practical problem from traditional bulking: the athlete may still want to develop or preserve muscle while also keeping body weight under tight control. In that setting, resistance training often has to continue during periods of energy restriction, which makes the question of how much muscle can be gained or maintained in a calorie deficit particularly relevant.
Does a Bigger Surplus Build Muscle Faster?
If bulking is not strictly required, the natural follow-up question is whether a larger surplus at least accelerates the muscle-building process for those who do choose to bulk anyway. A 2023 randomized trial addressed this directly, assigning resistance-trained lifters to eight weeks of training with a targeted 15% surplus, a targeted 5% surplus, or maintenance calories [4]. Notably, the study’s own authors reported that the intended difference between the two surplus groups did not fully materialize in practice — the moderate- and high-surplus groups ended up consuming similarly sized surpluses on average — which is part of why they treated the body-mass regression, rather than the group-based comparison, as their most informative analysis [4]. There was moderate-to-strong Bayesian evidence that the larger surplus group increased bench-press strength more than the moderate-surplus and maintenance groups, but the study’s broader post hoc regression analysis — conducted after unblinding and treated by the authors as their most generalizable finding given the small per-group sample sizes — found that a faster rate of body mass gain primarily predicted a faster rate of fat gain, not greater increases in one-repetition-max strength or muscle thickness [4]. The one partial exception was biceps brachii muscle thickness, which showed a weak positive association with body mass gain — plausibly because the biceps received the most direct training stimulus in the study’s program [4].
The authors’ own conclusion was direct: faster rates of body mass gain, and by extension larger surpluses, primarily increase the rate of fat gain rather than augmenting strength or muscle thickness gains [4]. This is a single trial with a modest sample size (17 completers after COVID-19-related attrition) — the authors themselves describe it as one of only a few studies to examine this question directly in resistance-trained lifters — so it should be read as suggestive rather than definitive, but it points the same direction as the broader overfeeding literature discussed above.
Protein’s Role Regardless of Energy Balance
Across the deficit, maintenance, and surplus studies discussed above, one variable shows up consistently as associated with favorable body composition outcomes: dietary protein intake. This is consistent with the broader protein intake literature, and it holds true whether the goal is preserving lean mass during a diet or maximizing lean mass gain during a surplus. In practical terms, this means the decision of whether to bulk at all is somewhat separable from the decision of how much protein to eat — a lifter at maintenance calories with adequate protein and a well-structured resistance-training program is working with the same core training and protein-related anabolic stimuli as a lifter in a surplus, without deliberately taking on the added fat-gain risk that comes with eating above maintenance.
Protein intake and total calorie intake are often treated as if they were the same variable, even though they can be adjusted separately. They do overlap to some extent, but it is entirely possible to consume enough protein — or even a relatively high amount — while keeping total calorie intake at maintenance or below it.
From a practical perspective, this distinction matters during fat loss. A person does not necessarily need to increase total energy intake simply to increase protein intake. In my experience, this can make dieting easier to structure because protein can be prioritized within the existing calorie target rather than being treated as a reason to eat more overall. Many people also find protein-containing foods relatively filling, which may make adherence to a calorie deficit easier for some individuals. So during a dieting phase, protein can be useful for two separate reasons: helping to support lean mass while total energy intake is reduced, and potentially making the diet easier to tolerate by improving satiety.
Conclusion: Is Bulking Necessary for Muscle Gain?
Bulking is not a biological requirement for building muscle. The evidence discussed here shows that muscle and lean mass can be gained without a deliberate calorie surplus, including at maintenance intake and, in some situations, during a calorie deficit. At the same time, energy intake still matters: a larger and more sustained deficit can make lean-mass gain considerably more difficult, particularly when the goal is to lose fat and build muscle at the same time.
The practical takeaway is that more food does not automatically mean more muscle. Resistance training remains the primary hypertrophic stimulus, adequate protein intake is important, and progressively increasing calories beyond what is needed appears more likely to increase body weight and fat gain than to produce proportionally greater muscle growth. This is also how I would approach the question in practice: make sure nutrition is sufficient to support training and recovery, but do not assume that a larger surplus is inherently better.
For many people, especially those trying to improve body composition rather than simply maximize scale weight, maintenance calories or a modest deficit may be a perfectly reasonable place to train. This can be particularly relevant for people with higher body fat, newer or returning lifters, and weight-class athletes who need to manage body weight while still preserving or developing lean mass. The main trade-off is not between “bulking” and “not building muscle,” but between how aggressively you pursue weight gain or weight loss and how much room you leave for muscle growth, recovery, and long-term adherence.
In my view, the most useful shift is to stop treating bulking and cutting as mandatory phases and instead see them as optional tools. A calorie surplus may still make sense in some situations, but it is not the only way to make meaningful progress — and eating more than necessary does not appear to buy proportionally more muscle.
Bibliography
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC6710320/
[3] https://pubmed.ncbi.nlm.nih.gov/34623696/
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10620361/
