Nutrient timing relates to the timing of our meals, with specific reference to the nutrients consumed around the workout (‘peri-workout’ nutrition). Firstly, it is important to understand where nutrient timing sits within the overall hierarchy of factors that contribute to dieting for body composition results. This is clearly illustrated in the diagram below, courtesy of Eric Helms.
Of primary importance is overall energy balance. This factor sits at the bottom, providing the foundation for the rest of the pyramid. Energy balance must be considered before any other factor. Once you establish how much you need to eat for your goals, you must then consider how this energy needs to be allocated with regard to macro- and micro-nutrients. How much protein, fat and carbohydrate will be required? Are you ensuring you are getting enough vitamins, minerals, phytonutrients etc? Only once this has been established do we need to really consider nutrient timing.
Recent research has provided a better picture of how nutrient timing can affect the results we get. The review carried out by Schoenfeld & Aragon (2013) provides great insight into this topic. Schoenfeld & Aragon (2013) highlight 3 important reasons for post-workout intake of protein and carbohydrate. They are: -
- Glycogen Repletion - ‘Muscle glycogen’ is what we call the stores of carbohydrate in the muscle. When we engage in physical activity, much of the energy provided comes from these stores of energy in our muscles. However, the average person engaged in a resistance training program is highly unlikely to deplete muscle glycogen stores beyond more than 35-40% within a session. Unless someone is engaged in some type of endurance-based sport, or is training multiple times per day, then there is no need to ingest carbohydrate immediately post-training. Having a meal containing both protein and carbohydrate is likely to be sufficient. This statement is backed up by the research of Parkin et al (1997). In this paper the researchers compared immediate post-exercise ingestion of high-glycemic carbohydrate with a 2 hour wait before ingesting the carbohydrate. No differences in glycogen levels were observed between the groups at 8 and 24 hours post-exercise. Immediately consuming carbohydrates post-workout is not necessarily required to replenish glycogen levels post-exercise.
- Preventing Muscle Breakdown - Muscle breakdown is not likely to be a problem provided you aren't training in a fasted state: “The classical post-exercise objective to quickly reverse catabolic processes to promote recovery and growth may only be applicable in the absence of a properly constructed pre-exercise meal” (Schoenfeld & Aragon, 2013). If you haven't eaten a meal for more than 4-6 hours pre-training then consuming nutrients immediately post-workout may be advisable. However, avoiding training in a fasted state is probably a better idea.
- Increased Muscle Growth - There has been no clear consensus within the research to suggest whether consuming protein immediately after training enhances muscle growth. Some studies (Esmarck et al, 2001 & Cribb & Hayes, 2006) found positive effects of consuming protein immediately after the training bout. However, other studies (Verdijk et al, 2009, Hoffman et al, 2009) found no difference between immediate consumption and a delayed consumption. The conclusion you could draw here is that immediate consumption is not necessary, but leaving it too long to eat probably isn't wise either.
Practical applications of the research can be distilled as follows: -
For those looking to maximise performance in the gym & avoid muscle breakdown, the training session should be sandwiched between meals no longer than 4-6 hours apart.
Protein is the most important macronutrient to consider in these meals as glycogen repletion isn't a major concern for most members of the general population training 3-5 times per week. However, the post-workout period is generally a good place to consume carbohydrates due to improved nutrition partitioning. However, consuming carbohydrates in the post-workout period won’t enhance muscle building based on current research (Staples et al, 2011, Koopman, et al, 2007). For overall satiety and anti-catabolic effects, it may be best to consume mixed meals - that is, meals that contain protein, carbohydrate and fat.
If you are undertaking training in a fasted or semi-fasted state, then the timing of your meal post-training becomes more important: -
“in the case of resistance training after an overnight fast, it would make sense to provide immediate nutritional intervention - ideally in the form of a combination of protein and carbohydrate - for the purposes of promoting muscle protein synthesis and reducing proteolysis” (Schoenfeld & Aragon, 2013)
However, if the goal is to increase lean muscle mass, I would suggest placing greater emphasis on consuming a pre-exercise meal, thereby training in a fed state. For somebody training very early in the morning, where consuming a meal 1-2 hours pre-training may not be practical, consuming 20g of whey protein will likely be enough to ensure adequate amino acid delivery during the training session (Tipton et al, 2007).
Take Home Points: -
It is important to remember that nutrient timing isn’t the most important factor to consider when dieting for improved body composition.
Peri-Workout nutrition is an important consideration, especially for those seeking to get the most out of their training.
Training sessions should be sandwiched between meals no longer than 4-6 hours apart
Unless taking part in endurance-based sports or multiple training sessions per day, the importance of carbohydrate post-workout is fairly limited. Protein is the most important macronutrient to consider.
Consuming nutrients immediately after training only becomes important if training in a fasted or semi-fasted state. Otherwise delaying consuming nutrients after training by a couple of hours will have no detrimental effects.
Aragon, A & Schoenfeld, B, “Nutrient Timing Revisited: Is there a Post-Exercise Anabolic Window?”, Journal of the International Society of Sports Nutrition, 2013.
Parkin, J et al, “Muscle Glycogen Storage Following Prolonged Exercise: Effect of Timing of Ingestion of High Glycemic Index Food”, Medicine and Science in Sports and Exercise, 1997.
Staples, A et al, “Carbohydrate Does Not Augment Exercise-Induced Protein Accretion Versus Protein Alone”, Medicine and Science in Sports and Exercise, 2011.
Koopman, R et al, “Coingestion of Carbohydrate with Protein Does Not Further Augment Post Exercise Muscle Protein Synthesis”, American Journal of Physiology, Endocrinology and Metabolism, 2007.
Tipton, K et al, “Stimulation of Net Muscle Protein Synthesis by Whey Protein Ingestion Before and After Exercise”, American Journal of Physiology, Endocrinology and Metabolism, 2007.
Esmarck, B et al, “Timing of Post-Exercise Protein Intake is Important for Muscle Hypertrophy with Resistance Training in Elderly Humans”, Journal of Physiology, 2001.
Cribb, P & Hayes, A, “Effect of Supplement Timing and Resistance Exercise on Skeletal Muscle Hypertrophy”, Medicine and Science in Sport and Exercise, 2006.
Verdijk, L et al, “Protein Supplementation Before and After Exercise Does Not Further Augment Skeletal Muscle Hypertrophy After Resistance Training in Elderly Men”, American Journal of Clinical Nutrition, 2009.
Hoffman, J 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.