Protein Timing

There is a distinct hierarchy of training- and nutrition-related variables at our disposal, some comprising our “foundation” for progress more than others. This hierarchy includes things like total caloric intake, exercise activity and/or daily expenditure, and food quality. From there, we trail off into smaller factors like supplementation, nutrient timing, and meal frequency to name a few. These variables and their levels of influence are important because it isn’t uncommon for emphasis to be placed on the less-impactful variables more so than others.

Why is this relevant? What does it matter here? Well it matters because plenty of people can save way more time and stress if they looked at the bigger picture rather than tinkering with the minute details of their day to day – details that may or may not significantly impact their overall results. This includes the ever-so-popular claims about what you must do (or not do) in order to make gains, otherwise all your work will “go to waste.” The anabolic window, or protein timing, falls into this category and is a topic that remains a bit unclear in the sense that we have little research on what role it really plays for more experienced, resistance-trained athletes.


We know that one’s total caloric intake, or calorie balance, ultimately determines whether or not an individual will gain or lose weight. We also know how essential dietary protein is for the athlete in order to optimize muscular adaptations and enhance recovery/repair processes. The question Hoffman and colleagues (2009) want to answer is whether or not the specific timing of one’s protein through the day plays any significant role for experienced strength and power athletes.

The Study

33 male strength and power athletes participated in this study while running a 10-week off-season conditioning program. Most of the men were college football players with resistance training experience and the remaining few were powerlifters. These subjects were randomly split into 2 different timing protocols as well as a control group in order to compare with a group without any supplemental intervention. One group was assigned a protein supplement timed in the morning and evening (AM/PM), while the other group was assigned to a protein supplement being provided immediately before and after workouts (pre-post). The control group received no supplementation, so a placebo was provided to them in place of protein.

Each subject was instructed to keep a training log throughout the 10-week period, and all groups were provided with the same training program to follow under lab supervision. The training prescribed was a 4-day, upper-lower split. Exercises were performed to a repetition-maximum range as well.

Dietary measures 

3-day diet recalls were done before and during week 9 of the study period where the subjects were asked to record everything they consumed, including the provided protein supplements, as accurately as possible. The protein supplement given to the subjects contained 42 grams of protein, 2 grams of carbs, and 0 grams of fat. 

Supplements (either protein or placebo) were prepackaged for distribution to the subjects who were instructed to consume their respective supplement twice per day for 10 weeks. Subjects in the AM/PM group reported first thing in the morning for their supplement and again later in the evening, while pre-post subjects reported for their supplements right before starting their training sessions and immediately afterwards. On non-training days, pre-post subjects still consumed their supplement at similar times of day (just as they did for their training days). 

A noteworthy point

One thing worth noting in this study is that urinary measurements were taken before and after the 10-week study period. This is important to clarify because urinary analyses are a means in which we can assess urinary urea nitrogen, or in other words, it’s a common way for researchers to determine an individual’s nitrogen balance. Nitrogen balance describes the balance between our nitrogen intake (via dietary protein) and nitrogen output or excretion (in the form of urea and other byproducts). Overall a key point here is that being in a positive nitrogen balance places us in an anabolic state and tells us that we are consuming enough protein in order to facilitate muscle growth and repair. A negative nitrogen balance would represent the contrary.

Key findings

Throughout the 10-week period, no significant changes in the participants daily caloric intake, carb intake, or fat intake were observed in any of the groups. As for protein specifically, there was a significant increase observed in the AM/PM group, but not in the pre-post group (interestingly) or in the control group. It is important to point out that the pre-post group was able to increase their relative protein intake by about 20%, but that change was not considered statistically significant. The protein composition of the diet overall was seen to significantly increase in both of the supplemental groups and was significantly greater than that of the control. 

By week 10, urinary nitrogen excretion was significantly increased in all of the groups. In addition to this, all of the subjects within each group were shown to be in a positive nitrogen balance for the full duration of the 10 weeks. This indicates that all participants in these groups consumed adequate amounts of protein to meet their individual needs as well as the demands of their training. 

As for body composition and any training-related changes, no significant changes in body mass was observed in any of the groups throughout the 10-week period. In addition to this, there were also no changes shown in body fat, fat mass, or lean body mass in any of the groups. 

Significant improvements were shown in 1RM squat for all three groups. For 1RM bench, significant improvements were exclusive to the AM/PM and pre-post groups, although there were no between-group differences; comparing the changes of each group between week 0 and week 10 showed no significant differences in 1RM squat or 1RM bench. 

Considerations moving forward

This study is one of the first to assess experienced, resistance-trained athletes and their protein timing. The results of this study make it known that specifically timing your protein pre- and post-training shows no enhancements or added benefit when compared to morning and evening protein supplementation. These types of results do need to be interpreted with a little caution, however, and should be tailored to the chosen population and the study’s individual parameters in question. 

Of the limitations the researchers mention, one I’d like to point out is the “relatively low” caloric intake of the subjects. The study references a general guideline for nutritional/caloric recommendations for men (44-50 kcal/kg body mass/d) and stated that in this present study, they found the subjects’ average intakes to be well below this value. This, in turn, is assumed to impact findings in that it could have limited improvements in body composition for the subjects. This is a generalized recommendation they are referring to, so while the recorded intakes may be relatively low compared to this value, we can’t really know for sure since every athlete’s caloric intake and daily needs will be very unique depending on their body composition, genetics, daily expenditure, and more. 

With that said, having seen all groups stay in a positive nitrogen balance, as stated prior, is a good sign in that we do know the subjects were getting enough protein daily to support their training, repair, and growth. I’d say the more important factor to consider moving forward is simply if you’re getting enough total protein in the day to facilitate those physique- and strength-related goals. Future work can always be done when it comes to resistance-trained individuals and nutrition, however, and this study shows us that protein timing does not provide added benefits to the performance or body composition of experienced, resistance-trained athletes.

Real life application

There are some limitations in this study and its findings that simply will not reflect every client we work with. Each client we work with not only come from different starting points and backgrounds, but they all have very different goals as well. A client’s dieting history, training experience, body composition, genetics, and even personal preference play a part in how we approach the diet and tailor a program specific to them. This especially goes for a client’s daily caloric needs, which seems to be the big limitation in the present study given that the diet was less structured and controlled excluding their assigned protein supplement.

Specific goals require specific measures to be taken with your nutrition. The majority of people who are just starting out can make a lot of positive changes through employing some simple guidelines such as making sure to get protein in each meal or increasing total protein intake in general. For the more advanced trainees who have those foundational habits already established, timing protein feedings appropriately shows to be an essential component in maximizing muscle protein synthesis throughout the day, mitigating protein breakdown, and even for one’s digestion and overall satiety levels.


Hoffman, J.R., Ratamess, N.A., Tranchina, C.P., et al. Effect of protein-supplement timing on strength, power, and body-composition changes in resistance-trained men. International Journal of Sport Nutrition and Exercise Metabolism. 2009; 19: 172-185.

Written By Gillian SanFilippo

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