Resistance training (RT) is one of the best lifestyle changes anyone can incorporate into their day to day due to the multitude of health benefits it provides. In addition to this, we know that having the basics of diet and training down should be the first step towards achieving any physique-, health-, or performance-related goal. Having that figured out, plenty of people will stumble upon more ways that they can further maximize their progress – one suggestion being that of employing more intentional peri-workout nutrition. 

The specific area of peri-workout nutrition in question here is post-workout nutrition, but more specifically the parts making up a post-workout meal that either prove to be beneficial or null in optimizing each training session to the fullest. Studies show that protein ingestion around resistance training enhances muscle hypertrophy and strength adaptations via stimulating muscle protein synthesis. This is a well-known fact and probably the first piece of information (and good information, at that) that many will learn upon entering the health and fitness realm. The question being debated more recently, however, is whether or not there’s an added benefit with mixed-nutrient supplementation post-workout compared to protein ingestion alone. Is it beneficial across the board, or simply a more context-dependent protocol?

The Study

In a 2015 study, Hulmi and colleagues sought to experiment with different approaches or regimens towards post-workout supplementation. 78 recreationally active men were split into three groups: whey protein, carbohydrates, and whey protein and carbohydrates. It’s thought that the addition of carbohydrates to protein supplementation would aid in responses to body composition and strength more so than having protein and carbohydrates on their own. In addition to these three groups, the subjects were further divided into two different resistance training programs. One RT program would focus on muscle hypertrophy and maximal strength while the other would aim for hypertrophy, strength, and power. Each would be run for 12 weeks alongside the post-workout nutrition interventions.  It should be noted that the subjects underwent a four-week long preparatory RT period. The rationale behind this decision was to standardize each subject’s training status and familiarize them to where effects of unfamiliar stressors (via training) would be minimal in those first few weeks of the study. This essentially would allow the researchers to bypass any “newbie gains” or strong learning adaptations typically seen at the onset of resistance training. After the preparatory period, subjects would train 2-3 times per week for the duration of the 12 weeks.

Post-workout protocols

Once training was completed for the day, each group would receive their post-workout supplement and were instructed to consume them immediately post-workout. The protein group received 30 grams of whey protein concentrate while the carbohydrate group received 34.5 grams of maltodextrin. These two quantities are chosen because they are isocaloric, or equal in caloric value, to one another. Finally, the protein plus carbohydrate group received a combination of the other groups’ doses: the 30 grams of whey protein and the 34.5 grams of maltodextrin together. 

Results

In the short 4-week preparatory RT period the subjects underwent, there were increases seen in fat free mass (FFM) as well as muscular strength. This is to be expected with introducing a new training stimulus/stressor to somewhat untrained and recreationally active individuals. Upon being later split into the three supplemental groups, there were no differences between each group at baseline. Now, it should be noted first and foremost that the two training regimens being used in this study and the comparison of the two is not the primary focus for the researchers and the present study, nor did the two training types have any effect on the nutrition responses to be observed. With that said, moving forward, the two training regimens will be referred together as one joint variable (although the paper does go into the statistics between both training types if you are interested!). 

Key findings

Interestingly enough, one of the first findings was that the protein group tended to consume fewer total calories when compared to the other groups. As we know, protein takes longer to break down and digest making it a more satiating macronutrient. This could explain the result here, although this discrepancy is not significant between the three groups when shown relative to body weight. 

Now onto what we are really here for – the body composition changes. After the 12-week supplement and training intervention, an increase in total fat free mass was observed in all three of the supplemental groups. It should also be noted that relative FFM in the protein group had increased more than the carbohydrate group. Muscle size was able to increase similarly for all three supplemental groups. 

Leg fat mass had decreased similarly in all three groups, while total fat mass seemed to have a nutrition x time interaction. This essentially means that over time, there was a decrease observed in total fat mass in the protein and protein plus carb group specifically, but not in the carbohydrate group. The total difference in fat mass was larger in the protein group than the carbohydrate group as well.

Implications moving forward

The only significant response observed regarding the supplemental protocols was the larger relative gains in FFM for the protein group compared to the carbohydrate group. This was mostly due to the protein group having a significantly larger drop in fat mass and a less significant increase in FFM, so it can be concluded that more desirable changes in body composition will be achieved via post-workout whey protein supplementation when compared to isocaloric carbohydrate supplementation.

What about adding carbs to protein? Well, this study supported previous findings that adding carbohydrates to protein post-workout did not enhance or improve muscular adaptations to resistance training. The results for the combination protein-carb group seemed to interestingly fall in between the carbohydrate and whey protein groups. One limitation to point out here has to do with the subjects chosen and the length of time – had they been more advanced/experienced trainees and given a longer amount of time, we would perhaps get more insight regarding the role of carbohydrates for athletes and muscular adaptations over time.

This doesn’t mean peri-workout carbohydrates don’t have a place – they absolutely do! Much more can be discussed regarding pre- and intra-workout carbohydrates and the benefits they provide for performance. Overall, context is important, and we must consider the sport and exercise being performed as well as the intensity and duration of the training bout in order to narrow down a protocol that optimizes nutrition and training variables for the athlete. If your goal is to maximize fat loss while performing resistance training, whey protein supplementation will be your best choice for your post-workout nutrition instead of carbohydrates.

Written By: Gillian SanFillippo