top of page

Gaining lean muscle without fat!?

*My disclaimer, any and all recommendations that arise from this work will likely only be of value to drug free athletes. Additionally, we will only be covering how an individual can implement a calorie surplus to gain muscle mass but may elude to lean body mass gains in a deficit if and when I see fit (my blog, my rules)*

The how to gain muscle and not gain fat conundrum

Put your hands up if you've ever tried to gain muscle / weight without gaining fat? The proverbial "chasing your tail" of the weightlifting/bodybuilding/strength sport world. We've all dreamed of it, and the old school magazines have assured us of the existence of this holy grail of "gainz" but how achievable is it really (if it does in fact exist)?

I hope this doesn't upset anyone but fat gain is a given. More so because we're constantly building and breaking down our fat stores (a.k.a. it's unavoidable) and, when in a calorie surplus, the "building side" outweighs the "breaking down side" creating a net gain of fat storage. It's important to note however that not all weight gain is created equal and we won't simply just gain fat if we introduce a calorie surplus.

So, how much of our calorie surplus will contribute to fat gain? Well, to be as honest as I can, it depends. It depends on a lot of factors actually (most of which we're yet to fully explore in the literature), and the hope that there is a "magic" number for calories, a "mythical" macronutrient ratio or the "one" food source you've not heard of but could be the key to the mystery doesn't (at least to our current knowledge) exist.

But, that doesn't mean there isn't data out there which we can interpret, evaluate and make practical recommendations and implementations from.

This article is going to cover that data and also give an insight into the various factors which can influence how you structure your dietary approach to achieve the utmost efficiency when it comes to "lean" gains.

Just to quickly get this question out of the way as I know it'll appear "Can I gain a significant amount of lean body mass whilst in a calorie deficit / weight loss phase?"

Technically, yes, but it depends on your current level of experience with weight training and or your beginning body composition state. Beginners and people with relatively high fat percentages (i.e. >20% bf for men) can gain muscle mass & strength in a calorie deficit which has been eluded to in multiple pieces of literature. It is possible that those with an intermediate level of experience with weight training may also be able to as well (depending on their given programming, macronutrient split, nutrient timing, supplementation, genetic propensity to gain lean body mass etc.).

For the record, there are no universally defined and or agreed upon definitions for level of weight training/ weight lifting/ bodybuilding experience however most tend to agree that;

Beginner - Typically been training for under one year.

Intermediate - Been training for greater than a year but hasn't achieved certain metrics related to strength in the most popularized, compound movements. These metrics can be interpreted differently from person to person with each holding their own standards for an "advanced lifter" e.g. being able to snatch your body weight for example.

Advanced - Typically been training for several years consistently with a universally recognizable and acknowledged base level of strength across all the major compound lifts and or achieved upwards of 80% of their genetic ability to gain lean body mass. e.g. someone able to dead lift 2 x their body weight (however even this may not fit into the category of "advanced" for some, it all depends on who you talk to). The sport of Powerlifting uses the "Wilks" score tally to determine lifters placing in competition based on their lifts achieved so this may be a useful tool in the future to use and or adapt to define different levels of lifting experience for general population - just a thought, but no one listens to me anyways so).

There's also an additional category of elite, but that's typically restricted for top national and international athletes in a given sport. Most individuals reading this article will fall somewhere between intermediate to advanced.

Ok, so now that we've gotten a little side tracked let's refocus our attention and bring it back to the question on hand "Can I gain muscle without gaining fat as an advanced athlete?"

So, to (somewhat) adequately answer this we're going to focus on two groups of data; the data which has directly investigated this question (trust me, it's a pretty dry well) and the data which covers overeating and how that can effect weight gain (both in terms of lean mass and fat gain) depending on diet content.

The data directly investigating calorie surplus and body composition changes in advanced athletes

The main study we can draw from the is 2012 study published by Garthe et al. which evaluated the effect of nutritional guidance in an 8 - to 12 - week weight-gain period in advanced athletes (which in this case referred to national level and or those competing for national level spots for their respective country - Norway).

Thirty-nine athletes were randomised to either a 'nutritional counseling group' (NCG) or 'ad libitum eating group' (ALG). All athletes continued their sport-specific training which included an additional four strength-training sessions per week. NCG followed a meal plan providing a positive energy balance, while the ALG athletes had an ad libitum energy intake.

The researchers found that the ALG group consumed on average 3,000 kcals a day with a macronutrient ratio of 18% PRO / 47% CARB / 35% FAT whereas the NCG group consumed on average 3,600 kcals a day with a macronutrient ratio of 20% PRO / 55% CARB / 25% FAT.

This was the data the researchers collected on bodyweight (BW), lean body mass (LBM) and fat mass (FM).

* Indicates significantly different from pre-study measures

** Indicates significant difference between groups

As you can see, the only measurement which was not significant between groups was the increase in LBM with the measurement in FM being fairly unnerving to you out there who are considering the "dirty bulk" method. These data do however reassure those of you who would rather look to gain weight slower and not go for the old "see-food" diet approach. It all depends on who's looking at them I suppose!

For the "dirty bulk" advocates in the crowd, it is worth noting that that these researchers also investigated how the intervention would effect the subjects' performance in certain tests; 40 m sprint time, counter movement jump height (CMJ) and one repetition maximum (1RM) in bench press, bench pull (yeah, no I don't know what that is either, some crazy Norwegian move, although I'd assume it's a rack pull or variation of a barbell row) and squat.

* Indicates significantly different from pre-study measures

Whilst the data doesn't indicate significant differences between groups, any powerlifter and or weightlifter would tell you a couple of percent makes all the differences in competition. It's also difficult to extrapolate the impact that the intervention did or did not have as the variation in strength for these major lifts was fairly vast (I'd go have a peak at the study if you're interested, as always it'll be in the references).

The interesting finding here is the squat difference. One of the major issues with this study is skewed gender population difference - 90% of the subjects were guys. Why is this important? Well, we actually know that, all things being equated for (size, LBM etc.) women are as strong if not strong and able to complete more repetitions for lower body movements than men. So it's likely the calorie surplus and weight training program would have elucidated different results in a group of predominantly women (and we can't really see the effect the intervention had on the female participants in this study as their data is "lost in the maelstrom" of other data, so to speak).

So, this is our sole cornerstone of evidence for when the research directly investigates "calorie surplus on body composition changes and performance in advanced athletes" and, suffice to say, doesn't overly support a "dirty bulk" approach (in an assumed non-drug using population). However, it may have some slight benefit to the extreme ends of strength sports athletics (who only have to perform one repetition at a time during competitions) but then we have to consider; how that alters their body structure and lifting form? Do they have to make a weight category? How will the deficit effect their strength on the day of competition? Would it mitigate any benefit from the weight gain phase and or cause more harm than good (because they gained a lot more weight than necessary and now have to diet longer and or harder to "make weight"? etc. All interesting questions that I'm sure the research will never investigate; Thanks nerds!

When I said the well was kind of dry, I did mean it. This is literally one of the only relevant and "good" pieces of work that have directly investigated the subject. We have a few that employ a ketogenic diet but they weren't controlled very well and or the population size tested was just too small. Also, most led to weight loss and or no change in muscle mass, which shows a distinct lack of understanding as to how to construct a nutritional intervention designed to "investigate a calorie surplus i.e. an amount of food that leads to weight gain".

The data directly investigating overfeeding; how could we use this instead to form the most efficient nutritional strategy to gain weight (in the form of LBM) whilst mitigating fat gain.

So, as mentioned, there isn't much for us to go on in terms of data related to the exact question we want to answer; ain't that always the case. What we have to do instead then is use our brains. Take what science has given us, digest it (nutritionist joke), understand it and warp it into something that we can personally use and or employ in our clients. There is no perfect solution; each person is unique and will require their own unique approach. So, what we can do, is use these findings, accept there isn't much "exact" data for our original question, and create our own approaches. Fun times!

Overfeeding; how much is too much?

Well, it depends. What we do know however is that a "Western Diet", defined as high dietary intake of processed foods rich in saturated fats and sucrose and low intake of fiber, is not a good approach. Especially for sedentary (non-active) populations. The general consensus; overfeeding (baseline energy intake plus 1000 kcal or 40–70% of baseline) healthy, sedentary adults with a diet moderately high in both carbohydrates and fats (35–50 % energy intake each) and low in protein (11–15 %) primarily results in a gain in FM. Not quite what we're looking for.

Not that these are necessarily translatable to our population but, if we take the findings from Carthe et al., (the previously mentioned study) and these findings, we can assume that for most folks anything between 600 - 1000 + kcals a day as a surplus is too much and will likely lead to an undesirable amount of fat gain.

However, does that change when we take into consideration dietary composition?

Does Dietary Composition Factor In?

Carbohydrates and Fats

In short, yes. And this isn't just isolated to your macronutrient ratios but also the kinds of foods you eat (at least as it relates to carbohydrates and fats).

Whilst it isn't clear whether certain kinds of carbohydrates can have more or less of an effect on the amount of fat you gain in a calorie surplus (the research on the subject is fairly terrible, typically overfeeding in an unrealistic fashion and with isolation of certain sugars which isn't how they appear in real world scenarios - I've put the references in but I wouldn't assume they'll be of much benefit), the data surrounding fats is however a tad more indicative of the effects different kinds of dietary fats can have on our body composition (and something we can actually draw practical recommendations from).

How did they test this? I'm glad you asked; muffins. Yes, fat laced muffins. Where's all the fun science when I want to join in!? One group was fed muffins containing more polyunsaturated (PU) fats (the "good" dietary fats) and other group was fed muffins containing more saturated (SA) fats (the "less good" dietary fats). Each group consumed around three of these muffins a day on average equating to around 750kcals and an energy increase of roughly between 20 - 25%.

To no the surprise of absolutely no one, both groups gained a significant amount of weight. It should be noted at this stage that both groups were sedentary which makes this next tidbit of information even more interesting. The fat mass gain in relation to the total weight gain of the group consuming the PU fat muffins was 50% whereas in the SA fat muffin group this figure increased to 81%. Weight gain didn't significantly differ between groups so we can ascertain from this study that a calorie surplus approach including foods richer in saturated fats as opposed to polyunsaturated fats may lead to a greater percentage of weight gained being fat mass. A smack in the face for "dirty bulk" fans saying that where you get your calories from doesn't matter.

To summarize, we don't have enough data to make any great assumptions on the effect of carbohydrate sources and their contributions to what percentage of weight gain will be attributed to increases in fat mass. However, simply employing common sense here would be the most advisable approach. Don't consume purely highly glycaemic, easily digestible carbohydrate sources; focus predominantly on wholegrains and or other complex carbohydrates and use the aforementioned "simple" carbohydrate sources around training and or in moderation to stave off binging.

When it comes to fats, quality does appear to matter in our quest to mitigate fat gain in a calorie surplus / weight gain phase. Unsaturated over saturated sources would be advised based on the findings. In the future it would be interesting to investigate how medium chain triglycerides and omega-3 polyunsaturated fatty acids effect the ratio of fat mass to total weight gain and whether they lead to a greater or lesser percentage of weight gain attributable to increase in LBM.


Everyone's favourite buzzword; protein. Thankfully, for me at least, we do actually have some relevant data to look at in relation to overfeeding with protein in athletic populations and the findings are pretty damn interesting.

Before we dive into the athletic populations, just a quick nod to a few studies that investigated overfeeding high protein diets in sedentary groups. The studies found that overfeeding high protein diets (which in this case was at least 20% of total caloric intake) led to significantly less gains in fat mass. A promising indicator of what's to come?

As a preliminary side note to these studies, none of them controlled for total calorie intake, so this may have skewed findings (but hey, we work with what we've got right).

My main man, captain protein, Jose Antonio (from the International Society of Sports Nutrition) loves, and I mean LOVES, throwing protein at people (and it's the studies he's either led or been involved in that I'd like to focus on).

In the first study I'd like to bring up, Antonio and protein partners examined 30 healthy men and women with an average of nine years of resistance training experience. Subjects were randomized into one of two groups: consume 4.4 g/kg of protein daily or to maintain current dietary habits for eight weeks. Both groups were also instructed to maintain their current exercise habits. Compared to the control group, the high-protein group consumed significantly more calories (+ 800 kcal) and protein (4.4 vs. 1.8 g/kg). Notably the high-protein group increased FFM (+1.9 vs. 1.3 kg) and reduced FM (−0.2 vs. +0.3 kg) compared to the control group despite eating an additional 800 kcal/d.

In a follow-up investigation, Antonio et al. randomized 48 healthy, resistance-trained men and women to consume a minimum of 3 g/kg of protein daily or to maintain current dietary habits for eight weeks while undergoing a standardized resistance training program designed to increase lean body mass. He had them curling like mad and injecting whey protein basically (terrible internet fitness humour and complete sarcasm).

Compared to the control group, the high-protein group consumed significantly more calories (+ 490 kcal) and protein (3.4 vs. 2.3 g/kg). Both groups significantly increased FFM and significantly reduced FM compared to baseline, but, once again, the reduction in FM was significantly greater in the high-protein group compared to the control group (−1.6 vs. −0.3 kg). It should be noted however that in this study the protein group did gain significantly less weight overall than the control group.

In another study Antonio and pals conducted a randomized, crossover (they try one thing for a while then try another after a wash out period) trial in which 12 resistance-trained men consumed a high-protein diet or their habitual diet for eight weeks each. Throughout the 16-week intervention, the participants followed their own strength and conditioning program. Compared to the control treatment, the high-protein treatment consumed significantly more calories (+ 370 kcal) and protein (3.3 vs. 2.6 g/kg).

There were no significant differences between the control and high-protein treatments for any body composition variable. However, nine of the 12 participants showed a reduction in FM during the high-protein diet phase.

The final study I'd like to highlight was carried out by Campbell et al., who examined 17 resistance-trained female subjects that were matched for total fat mass and randomized to a high-protein (2.4 g/kg/d) or control group (1.2 g/kg/d) for eight weeks in conjunction with a resistance-training program. The high-protein group consumed significantly more calories (+400 kcal) and protein than the control group, but there were otherwise no restrictions or guidelines placed on their diet. The higher protein diet was shown to be superior to a lower protein diet for increasing FFM, but both diets similarly reduced FM.

What we can extrapolate from these studies are three key points;

  1. Protein is good; it appears to not only increase FFM in a calorie surplus but also mitigate fat gain. It also allows you to consume a notable surplus without increases in FM (a nod to it's effectiveness at maintaining body weight / weight loss long term too).

  2. Changes in FFM are not different between a 2.6 and 3.3 g/kg/d protein intake suggesting there may be an upper limit to protein intake in relation to gains in FFM (in non-drug using athletes).

  3. Consuming above 3 g/kg protein in these studies led to reductions in FM compared to eating 2.6 g/kg or less. So somewhere between these two intakes may lie in the "sweet spot" for protein intake in maximizing FFM gains and mitigating increases in FM whilst overfeeding.

Dietary Composition Summarized

Whilst the dietary ratio of carbohydrate to