Bulking: Team Lean or Mass Monster?

To bulk or not to bulk, that is the question. Or at least part of it. Within the resistance training and bodybuilding community, the consensus has always been that an individual is best served cutting to low levels of body fat before commencing the subsequent bulk in order to potentiate muscle gain. However, we are now coming to realise that there is more to the muscle gain equation than simply getting lean before putting on mass.

Deciding whether to bulk or cut can become a conundrum, if you let it. An individual trying to maximise long-term muscle growth will likely be faced with an array of decisions:

Do I need to be “lean” before I start my bulk and if so, how lean? 

How large should my surplus be?

How fast should I gain weight? 

When should I stop bulking? 

Whilst it is easy to become overwhelmed with the amount of noise surrounding the topic of gaining muscle, the aim of this article is to highlight the signal and give you a better understanding of the variables involved when deciding to enter a bulking phase and how to more effectively plan your nutrition.

In the realm of bodybuilding, we often see competitors drop to sub 10% body fat in preparation for a show. This process is otherwise known as the ‘contest prep diet’ which is typically followed by a period of recovery or reverse dieting before the athlete then enters the “off-season”. In the off-season, athletes will spend extended periods of time in a caloric surplus, with the desired outcome being to maximise the accumulation of muscle mass. During this period, an athlete has little choice but to start their massing phase from extremely low levels of body fat. What is important to consider is that a physique competitor, by virtue of the sport, will also have a limit of how much fat they are willing to accrue during their off season. This is due to the fact that any excess fat gained during their off season will eventually have to be lost in preparation for the next show. These observations give rise to two important questions: 

  1. Should this approach be used by the average recreational gym-goer?
  2. If not, what is the best course of action when looking to maximise muscle gain?

It has been suggested that starting a bulk from low levels of body fat potentiates muscle growth by improving an individual’s “P-Ratio”. The P-Ratio, short for Partitioning Ratio, describes the portion of muscle mass gained or lost for every unit of change in total body weight. The theoretical mechanism behind the importance of the P-Ratio in the context of muscle gain is that lower body fat percentages result in increased insulin sensitivity, leading to the body partitioning calories for muscle tissue synthesis, as opposed to body fat. However, if true, and if the P-Ratio does indeed play a significant role in our efforts to maximise muscle gain, we are faced with the question of how lean is optimal to optimise the partitioning of nutrients towards muscle gain as opposed to fat and at what point does insulin sensitivity decrease, if at all, during a mass gaining phase when body fat levels climb to a point that potentially impairs the P-Ratio.

These questions become even more relevant for populations who may be setting themselves back by spending extended periods of time in a caloric deficit or on the other end of the spectrum, are sabotaging their muscle building potential by ending their bulk prematurely through fear of gaining too much body fat. In the case of extended caloric deficits, it has been well documented that as physique competitors and bodybuilders drop to unsustainable levels of body fat, their anabolic hormones become negatively impacted. One study (1),  found that severe energy restriction and extremely low body energy reserves resulted in the decline of 3 key anabolic hormone levels (Insulin, IGF-1 and testosterone) in bodybuilders prior to competition. 

All three of these hormones play a crucial role in the muscle building process due to their anabolic properties, meaning they can positively influence the synthesisation of new tissue, the storage of energy within the cells and constructive metabolism. The primary male sex hormone, Testosterone plays a key role in the development of male reproductive organs as well as being responsible for physical characteristics of adult males such as body hair growth and muscle tissue synthesis. As with most naturally occurring hormones, free-testosterone levels vary from person to person and can be negatively influenced by lifestyle factors including: stress, lack of sleep,  alcohol consumption and excess body fat. Like testosterone, IGF-1 and insulin are anabolic hormones capable of stimulating cellular proliferation as well as regulating vital processes within the body such as glucose metabolism; IGF-1 is also a mediator for the secretion of human growth hormone (HGH), which regulates muscle and bone growth as well as sugar and fat metabolism. As shown by  Mäestu, J, et al (1), negative energy balance can decrease levels of all three of these hormones, potentially compromising the muscle building process. Whilst such hormonal changes are virtually unavoidable in competitors, the negative effects on muscle building, mood and energy levels can only be a detriment to those without desires of stepping on stage. 

In contrast, it is reasonable to assume that most seasoned athletes and physique competitors may limit the extent of their bulk knowing that any fat accumulated will eventually equate to a proportionate time in a deficit. Furthermore, gaining excessive amounts of body fat may potentially lead to an increase in total fat cell count, and considering that fat cells only shrink in size in response to a calorie deficit (i.e. they are not lost/degraded completely), this may be an undesirable outcome for anyone interested in long term body composition improvements. Unlike competitive athletes and physique competitors, recreational lifters are not required to maintain their body fat levels within a certain limit. As is the case anecdotally, many every-day gym goers pull the plug on their muscle building endeavours prematurely as soon as they lose sight of their illusive abs, without realising the negative implications this might have on their physique development over the long haul. Without spending sufficient time in a dedicated bulking phase, including a surplus of calories, an individual may not be optimising their ability to gain muscle. For drug-free lifters, muscle growth is often very slow and requires a lot  of commitment and consistency. Whilst gaining muscle is possible during a period of negative energy balance, this phenomenon is more commonly found in beginners and untrained individuals. One study (7) found that when subjected to a 21-week resistance training protocol, significant increases in both maximal force and muscle cross-sectional area were found in untrained men, when compared to strength athletes. This may be a good indication that new lifters are more efficient at adapting to resistance training stimuli. For more experienced athletes however, muscle growth is slower and optimising the process requires more vigilance in terms of nutrition, in order to fully support productive training. With a surplus of calories, the body is able to not only recover from training sessions, but also utilise energy for processes involved with synthesising new muscle tissues. Despite this, an individual would still need to spend enough time in a surplus to experience noticeable growth. As shown in the aforementioned study (7), trained athletes on average were only able to increase muscle cross-sectional area by 1.8% over 21 weeks. Given that this figure is an average, it is possible that certain individuals from a non-athletic background may see growth at an even slower rate. Furthermore, once in a caloric deficit, the pool of resources used for muscle growth is diminished and the body begins to favour the use of calories for the maintenance of basic bodily functions as building muscle no longer becomes a priority.  By constantly yo-yoing between periods of bulking and cutting within a relatively short time-frame, an individual may not be allowing themselves enough time to gain the desired muscle mass. 

Does this mean all non-competitive lifters should throw caution to the wind and employ a “See Food” diet, with hopes of growing like a Ronnie Colman shaped weed? 

Probably not. However, interestingly, Hattori and colleagues (2) , showed that despite having excessively high levels of body fat (20% – 30%), elite Sumo wrestlers have been able to build large amounts of fat free mass. From this, it would be fair to assume that being lean (by today’s standards) is not necessarily a requirement when looking to build large quantities of muscle mass for certain individuals. There is however a level of nuance involved in situations such as these. Whilst Sumo wrestlers, linebackers and even professional strongmen have been found to gain lean tissue gain without issue in the presence of excess fat mass, these circumstances may not apply to the average gym goer. One could assume that the athletes in question are genetic outliers, and make up an incredibly small percentage of participants in their sport, let alone the population as a whole. As a result, they may be genetically predisposed to building more muscle in response to resistance training than others may, meaning they are less likely to experience the negative effects of fat gain on muscle hypertrophy. This may in part be due to naturally elevated levels of free-testosterone which can also increase baseline levels of skeletal muscle which in turn leads to greater potential increases in the future. Whilst not established, one could argue that such hormonal profiles are more likely to be found in successful athletes and elite drug-free competitors.

Whilst certain individuals may find that their ability to gain muscle is not hindered by increased body fat, there may still be negative consequences to other aspects of their health. A study by Jankowska et al. (3), found that total testosterone levels were negatively related to BMI, percentage fat mass and waist-to-hip ratio in young Polish males. A 2018 study by de Mutsert et al. (4) also found that abdominal subcutaneous adipose tissue and visceral adipose tissue  was associated with insulin resistance in men whilst in women, visceral fat was particularly associated with insulin resistance and insulin secretion. From this, it is plausible that as the average lifter ventures deeper into their bulk, body fat and subsequent visceral fat accumulation may begin to have detrimental outcomes on markers of health, potentially attenuating their muscle building endeavours.

Whilst there may be individuals who are capable of achieving levels of muscle mass akin to an anime protagonist whilst also holding excessive quantities of body fat, it is unlikely to be a common occurrence. From the data, we can see that whilst ending a bulk at the first sign of less visible abs is likely to be overkill, it is probably wise to stay in the realm of what is considered to be healthy. Whilst this number can vary depending on age and other factors, a body fat percentage of 6% – 24% for men and 13% – 31% for women is a reasonable estimate as stated by The American Council on Exercise (5). It would also be fair to conjecture that an individual who is not competing or prepping for a physique competition should avoid spending extensive amounts of time in an energy deficit and refrain from dropping to body fats below what is considered healthy, in order to maintain endocrine function, athletic performance and recovery.

Once an individual has outlined the starting point of their mass gain, they are then faced with decisions regarding the process of bulking itself. Whilst a larger caloric surplus has been shown to speed up rates of muscle growth, it will also result in a much greater build up of fat mass. Higher levels of body fat may then result in increased visceral fat, which has been shown to negatively impact health, alongside needing to spend more time in an energy deficit, in order to bring body fat levels down to a point where those illusive striations are once again visible. In the case of the latter, drug-free athletes are faced with the risk of muscle loss the longer they continue cutting. In the case of the former, the ability to gain muscle may be impaired by overall health deterioration.

It would seem that an optimal middle ground would be a modest rate of weight gain, whereby an individual can spend sufficient time in a slight to moderate surplus. This would then provide conditions conducive to hard training, ample recovery and ultimately, muscle growth. Even for physique competitors, slower rates of gain would mean less time needing to be spent in the inevitable cut and whilst you can argue that a smaller surplus means slower muscle growth, you could also argue that longer periods between shows/competitions would remedy this issue. A year or even two years spent focusing on productive training and recovery would likely see fantastic gains for most lifters regardless of their level of advancement.

When approaching the discussion of what is optimal, it’s important to consider what is practical, both in terms of weight loss and gain. The average gym enthusiast with a 9 – 5 job isn’t going to want to spend extended periods of time at a body fat that makes them feel like a cold, hungry walking anatomy chart and if they do, they’ll soon realise being shredded isn’t always worth the level of suffering required to maintain it. In contrast, leaner individuals may find holding extra total mass and body fat results in a level of discomfort, without necessarily reaching the point of what is considered “unhealthy”. Months of overfeeding and feeling bloated may be what is required in order to maximise muscle growth, however for most lifters, a slower rate with a smaller surplus may be far more suitable. Although potentially not as productive, the modest middle ground of slowly gaining weight within the range of healthy body fat levels will likely still see great results whilst also promoting adherence, enjoyment and consistency in the long run.

In conclusion, it’s important to consider one’s goals and lifestyle when assessing the need to cut or the rate of which to bulk. Whilst it may be possible to gain and maintain high levels of body fat and still see sustained muscle growth, individuals may wish to consider the potential risks posed to their health. The recommendation by Helms (6) of 0.5% – 1.5% of bodyweight per month is a great starting point for most individuals, however it’s important to clarify that more aggressive rates of gain may still be viable for certain populations. On the other end of the spectrum, cutting to sub 10% body fat may not be worth the time and effort unless in preparation for a specific outcome; for natural athletes looking to begin their bulk I would recommend a body fat percentage of 10% – 15% for males and 16% – 21% for females. This will allow the trainee to start relatively lean without needing to unnecessarily restrict calories in order to reach unsustainably low levels of body fat. Whilst there are certain guidelines you can follow, it’s worth remembering that an element of trial and error will be required when finding what is optimal for a given individual. Patience is also a valuable tool and as a lifter progresses through their training career, the more efficient and effective subsequent diet and training protocols become. Whilst there will always be an element of uncertainty and nuance surrounding the decision to cut or bulk, the best decision will usually take the form of moderation, practicality and sustainability.

Key takeaways:

  1. A body fat range of 10% – 15% for males and 16% – 21% for females is an ideal place to start for a bulk.
  2. Non-physique competitors should avoid prolonged energy restriction and unsustainable levels of body fat in order to maintain endocrine function and potentiate muscle growth.
  3. Gaining 0.5% – 1.5% of body weight per month is a good starting point for most individuals.
  4. Individuals may wish to take into consideration what is comfortable and sustainable, in terms of body fat accumulation when in a bulking phase.
  5. Body fat accumulation is a natural byproduct of an energy surplus and is to some extent required for an effective bulk. Some individuals may find bulking at more aggressive rates to higher levels of body fat is more optimal for their needs.


1. Mäestu, J., Eliakim, A., Jürimäe, J., Valter, I., & Jürimäe, T. (2010). Anabolic and catabolic hormones and energy balance of the male bodybuilders during the preparation for the competition. Journal of strength and conditioning research, 24(4), 1074–1081. https://doi.org/10.1519/JSC.0b013e3181cb6fd3

2. Hattori, K., Kondo, M., Abe, T., Tanaka, S., & Fukunaga, T. (1999). Hierarchical differences in body composition of professional Sumo wrestlers. Annals of human biology, 26(2), 179–184. https://doi.org/10.1080/030144699282886

3. Jankowska EA, Rogucka E, Medraś M, Welon Z. Relationships between age-related changes of sex steroids, obesity and body fat distribution among healthy Polish males. Med Sci Monit. 2000 Nov-Dec;6(6):1159-64. PMID: 11208473.

4. de Mutsert, R., Gast, K., Widya, R., de Koning, E., Jazet, I., Lamb, H., le Cessie, S., de Roos, A., Smit, J., Rosendaal, F., & den Heijer, M. (2018). Associations of Abdominal Subcutaneous and Visceral Fat with Insulin Resistance and Secretion Differ Between Men and Women: The Netherlands Epidemiology of Obesity Study. Metabolic syndrome and related disorders, 16(1), 54–63. https://doi.org/10.1089/met.2017.0128

5. The American Council on Exercise 2009, What are the guidelines for percentage of body fat loss. [Accessed 07/06/2021]. https://www.acefitness.org/education-and-resources/lifestyle/blog/112/what-are-the-guidelines-for-percentage-of-body-fat-loss/

6. Helms, E 2019, ‘When Gaining Muscle, the Tortoise Beats the Hare’, Monthly Applications in Strength Sport, Volume 3, Issue 6.

7. Ahtiainen, J.P., Pakarinen, A., Alen, M. et al. Muscle hypertrophy, hormonal adaptations and strength development during strength training in strength-trained and untrained men. Eur J Appl Physiol 89, 555–563 (2003). https://doi.org/10.1007/s00421-003-0833-3 

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Bhasin, S., Woodhouse, L., Casaburi, R., Singh, A. B., Bhasin, D., Berman, N., Chen, X., Yarasheski, K. E., Magliano, L., Dzekov, C., Dzekov, J., Bross, R., Phillips, J., Sinha-Hikim, I., Shen, R., & Storer, T. W. (2001). Testosterone dose-response relationships in healthy young men. American journal of physiology. Endocrinology and metabolism, 281(6), E1172–E1181. https://doi.org/10.1152/ajpendo.2001.281.6.E1172

Sousa, L., Marshall, A. G., Norman, J. E., Fuqua, J. D., Lira, V. A., Rutledge, J. C., & Bodine, S. C. (2021). The effects of diet composition and chronic obesity on muscle growth and function. Journal of applied physiology (Bethesda, Md. : 1985), 130(1), 124–138. https://doi.org/10.1152/japplphysiol.00156.2020

Ribeiro, Alex & Nunes, João Pedro & Schoenfeld, Brad & Aguiar, Andreo & Cyrino, Edilson. (2019). Effects of Different Dietary Energy Intake Following Resistance Training on Muscle Mass and Body Fat in Bodybuilders: A Pilot Study. Journal of Human Kinetics. 10.2478/hukin-2019-0038.

Rossow, L. M., Fukuda, D. H., Fahs, C. A., Loenneke, J. P., & Stout, J. R. (2013). Natural bodybuilding competition preparation and recovery: a 12-month case study. International journal of sports physiology and performance, 8(5), 582–592. https://doi.org/10.1123/ijspp.8.5.582

Hulmi, J. J., Isola, V., Suonpää, M., Järvinen, N. J., Kokkonen, M., Wennerström, A., Nyman, K., Perola, M., Ahtiainen, J. P., & Häkkinen, K. (2017). The Effects of Intensive Weight Reduction on Body Composition and Serum Hormones in Female Fitness Competitors. Frontiers in physiology, 7, 689. https://doi.org/10.3389/fphys.2016.00689

Patel, P., & Abate, N. (2013). Body fat distribution and insulin resistance. Nutrients, 5(6), 2019–2027. https://doi.org/10.3390/nu5062019

Leroith, D., Scheinman, E. J., & Bitton-Worms, K. (2011). The Role of Insulin and Insulin-like Growth Factors in the Increased Risk of Cancer in Diabetes. Rambam Maimonides medical journal, 2(2), e0043. https://doi.org/10.5041/RMMJ.10043 


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