nutrition, training, diet

Energy surplus and muscle hypertrophy

How can you not read a paper named "Magnitude and Composition of the Energy Surplus for Maximizing Muscle Hypertrophy: Implications for Bodybuilding and Physique Athlete" [1] when you see Alan Aragon's name under it? Alan Aragon and Brad Schoenfeld reviewed the literature to delineate the role of energy intake in muscle hypertrophy. Specifically, this review was aimed at bodybuilders and physique athletes.

The review is subdivided into several sections covering:

  • Hypocaloric conditions (an energy intake deficit)
  • Eucaloric conditions (an energy intake equal to energy expenditure)
  • Hypercaloric conditions (an energy intake surplus)
  • Magnitude of the surplus
  • Macronutrient composition
  • Practical application

I'll highlight the important points of each of these sections in this post.

Hypocaloric conditions (an energy intake deficit)

It is well known that an energy deficit impairs muscle growth. Quite in fact, it can entirely impair muscle growth in trained individuals (especially when they're already lean). Mechanistically, this might be explained by downregulation of the mTORC1 pathway and activation of the energy sensor protein AMPK. I briefly touch upon the regulation of mTORC1 by energy status via AMPK in a section of a review paper I published in 2016.

What is highlighted in this section, is that resistance training concurrent with a high protein intake can increase lean mass despite an energy deficit. Although this effect is clearly diminished in trained lean individuals, this holds especially true for untrained, obese individuals.

An interesting study they highlight in this regard is one by Donnelly et al. [2]. Fourteen obese women were put on a very low calorie diet (803 kcal daily) for 90 days. Seven of them performed concurrent weight training and the other seven remained sedenary. As you would expect with such a low energy intake in obese individuals, they lost a shitload of weight. On average, they lost 16(!) kg, that's 35 lb. While fat mass and fat free mass decreased to the same extent in both groups, muscle biopsies provided some interesting information. They showed that the muscle fiber cross sectional area increased in those who performed weight training, but remained unchanged in those who remained sedentary. While the hypertrophy might have been just regional to that specific muscle, I wouldn't expect it (certainly given it's a leg muscle and the subjects lost a lot of body weight). It should be appreciated that some fat free mass loss cannot be attributed to muscle loss. (And similarly, if you measure an increase in fat free mass, you shouldn't directly attribute it to beign muscle mass.)

Eucaloric conditions (an energy intake equal to energy expenditure)

When energy intake equals energy expenditure, that's called eucaloric. In other words, you're eating at energy maintenance. These conditions are more favorable for building muscle. The paper mainly seems to go off on a recent meta-analysis by Morton et al. [3]. (Aragon and Schoenfeld were also both co-authors of this meta-analysis.)

Studies involving hypocaloric conditions were excluded from the analysis. It looked at the effect of protein supplementation in conjunction with resistance exercise on gains in muscle mass. They argue that because of a lack of a meaningful increase in energy intake from baseline across the analysed trials, as well as relatively minor gains in FFM, the conditions can be interpreted as being eucaloric. (Since this was not a purposeful aim of the study.)

They found that protein supplementation increased fat-free mass by 0.75 kg on average in resistance-trained individuals. To give this a little bit more perspective: the trials with trained individuals lasted 10 weeks on average. Honestly, that's quite a lot for a relatively minor dietary change in such a relatively short timeframe. Just adding some extra protein.

The gains were far less overall (0.3 kg) and non-existent (-0.01 kg) in the elderly. Aragon and Schoenfeld conclude this section with "These relatively unremarkable gains indicate the importance of a purposeful caloric surplus combined with progressive resistance training when maximizing muscle hypertrophy is the goal." I cannot say I fully agree with this, given that I find the increase quite solid in the resistance-trained individuals for such a minor dietary change.

While this might be suboptimal, I think the take-home message for resistance-trained individuals can be that you can gain a substantial amount of muscle mass when protein intake is adequate under eucaloric conditions.

Hypercaloric conditions (an energy intake surplus)

It stands to reason that an energy surplus allows more muscle hypertrophy. An interesting trial they mention is one by Bray et al. [4]. This trial was performed particularly well. The main reason for this is that they put the subjects in a metabolic unit, thus entirely being able to control their energy intake.

The study examined 25 healthy, weight-stable male and female subjects and overfed them for 8 weeks after an initial weight-stabilizing diet of 13-25 days. They were randomized to a low protein (5% of energy intake), normal protein (15%) or high protein (25%) diet. Energy intake was increased by nearly 1000 kcal daily. So that's quite a lot.

What was interesting is that all three groups gained about the same amount of body fat. However, the normal and high protein diet groups also gained lean body mass (as measured by DXA). So just eating a lot more calories, while getting enough protein, gets you to increase lean body mass.

Aragon & Schoenfeld continue to highlight that it's important to realize that lean mass does not equal muscle mass. Which I can fully agree on. This is important when interpreting research. Additional measurements, like ultrasound, MRI, CT or muscle fiber cross sectional area, can give a whole lot more confidence in whether or not a change in lean mass is due to a change in muscle mass.

Magnitude of the surplus

Just as energy intake can affect muscle hypertrophy, so can training status and body composition. Aragon and Schoenfeld argue that untrained (/detrained) individuals have a larger potential to fulfill in muscle gains. Therefore it is possible that lean, trained subjects are more prone to fat gains with exceedingly larger energy surpluses. This is something I can agree with. In general, I advice more advanced, lean, athletes, as well as women (because of their relatively smaller growth potential) a smaller energy surplus than beginners who wish to increase their muscle mass as much as possible. Undoubtedly, the more advanced athletes will also gain a bit more muscle mass with large energy surpluses. However, when they start cutting again afterwards, they need to lose more fat and I guesstimate that whatever extra muscle mass they gained will vanish with it.

A trial they mention is one by Rozenek et al. [4]. I feel bad for the test subjects, as they were given a 2010 kcal supplement in addition to their regular diet. I mean, I like food. But I don't think I'd like stuffing down an additional 2010 kcal in the form of their supplement.

There were three groups. One received a high protein 2010 kcal supplement (356 g carbs, 106 g prot), one received an isocaloric carb 2010 kcal supplement, and one just served as a control group. All three performed resistance training and had a reasonable protein intake (atleast 1.3-1.5 g/kg bw daily). At the end of the 8-week trial, all groups had gained significant amounts of lean mass (2.9, 3.4, and 1.4 kg, respectively). This suggests that, atleast in "beginning weight trainers", a calorie surplus can substantially increase lean mass gains when protein intake is sufficient. However, as Aragon and Schoenfeld point out, these results should be interpreted with caution. Both groups who received the supplement dramatically increased their carbohdyrate intake. This will surely lead to some more glycogen and accompanying water. (Which can be measured as lean mass.)

Now contrast these results with another study they mention, but with elite male bodybuilders [5]. A small group of subjects was randomized to either a high energy intake (6087 kcal daily) or a moderate energy intake (4501 kcal daily), for 4 weeks. The high energy intake lead to a larger (1.0 kg) increase in lean mass than the moderate energy intake (0.4 kg). However, there was no significant change in fat mass in the moderate energy group (+0.8 %), whereas the high energy group saw a significant increase of 7.4 %. It should be noted that body fat measurements were done using a caliper, and then a formula was used to derive lean mass. I'm doubtful in how accurate this is, especially over such a short timespan. Either way, these results might suggest that very well trained individuals mostly just get fat with large surpluses.

Macronutrient composition

I guess this section can be summarized in just a few sentences. If you eat sufficient protein (1.6 to 2.2 g/kg bw daily), overeating it will perhaps help a litte bit extra with building muscle. Additionally, it might perhaps have an effect on keeping fat off (but there are quite a few catches to the trials with demonstrate this). Overeating fat is likely not the best idea, so carbohydrates seem to be the macronutrient of choice when overeating.

Practical application

I'll just leave this here.

Energy surplus guideline summary


  1. Aragon AA, Schoenfeld BJ. Magnitude and Composition of the Energy Surplus for Maximizing Muscle Hypertrophy: Implications for Bodybuilding and Physique Athletes. Strength & Conditioning Journal. Publish Ahead of Print, 2020.
  2. Donnelly JE, Sharp T, Houmard J, et al. Muscle hypertrophy with large-scale weight loss and resistance training. Am J Clin Nutr 58: 561–565, 1993.
  3. Morton, Robert W., et al. "A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults." Br J Sports Med 52.6 (2018): 376-384.
  4. Rozenek, R., et al. "Effects of high-calorie supplements on body composition and muscular strength following resistance training." Journal of Sports Medicine and Physical Fitness 42.3 (2002): 340-347.
  5. Ribeiro, Alex S., et al. "Effects of different dietary energy intake following resistance training on muscle mass and body fat in bodybuilders: a pilot study." Journal of Human Kinetics 70.1 (2019): 125-134.