With so many different nutritional theories out there, many people find themselves inundated with information that may or may not be credible. Nutrition is not a black and white topic like some make it out to be. The challenge with giving precise/effective nutrition advice to broad demographics is that it’s a topic that necessitates personalization; it operates in shades of grey. A multitude of intrinsic (e.g. metabolic rate, endocrine functions, immune response, etc.) and extrinsic (e.g. caloric intake, activity level, etc.) factors contribute to how one utilizes nutrients.
Obviously a young, 220lb male bodybuilder looking to add as much muscle as possible to his physique will have different nutrient requirements than a 50-year old, 120lb soccer mom prepping for a week vacation in the Caribbean. It may seem intuitive, but this just supports the point that context must be considered when optimizing someone’s diet.
A final point to consider is that people tend to migrate towards extremes in the health and fitness realm. For example, many bodybuilders may come across a study that notes barbell curls are more efficient than dumbbell curls for bicep stimulation; more often than not, this gets interpreted as, “Dumbbell curls are a useless biceps exercise.” Such an all-or-nothing mentality will greatly hinder you in the long run. The goal isn’t to find what’s most extreme, but what is optimal, and more importantly, what’s practical for each individual. Even if a certain extreme protocol is optimal, more often than not it’s impractical, rendering it useless.
With that in mind, this guide will delve into the topic of proper post-workout nutrition. First it will cover the physiological responses to resistance training, the research behind post-workout nutrition and finally how to go about setting up your post-workout meal.
Physiological Responses to Resistance Training
Before moving onto the nutritional sections of this guide, it’s imperative to have at least a rudimentary understanding of what happens physiologically to our bodies during and after sessions of resistance/weight training. This can be tricky to summarize since there is a vast array of research showing that different training variables (i.e. volume, intensity, frequency, etc) elicit different physiological responses. (1)
A trainee that is lifting purely to increase strength (such as a powerlifter) will likely have a different approach to training than a physique competitor/bodybuilder looking to build more muscle (more on why this is later in the guide).
For now, let’s assume the trainee is performing a routine that utilizes moderate volume (e.g. 3-4 sets of 8-12 reps per exercise), moderate intensity (e.g. a weight that challenges the individual but does not incur failure on the last rep) weight training 3-4 times per week. This is a modest approach in terms of activating different muscle fibers. (2)
Now if we apply this program to John (or Jane) Doe, a variety of different physiological responses/adaptations will occur. When John/Jane performs their exercises, they are exerting a contractile force with the necessary muscle(s) during each repetition; to advance this contractile force the muscle cells use energy, in the form of adenosine triphosphate (ATP), and eventually reach a point of exhaustion where no more repetitions can be performed (called “muscular failure”). This is an abridged overview of what happens during anaerobic exercise such as intense weight/resistance training, but nevertheless it’s sufficient for the purposes of this guide.
Continuing on, once John/Jane has exhausted muscles sufficiently through weight training, the muscle cells will be damaged and develop a buildup of metabolites in the surrounding tissue. This leads to an inflammatory-repair response in the interim after training has occurred, known as delayed-onset muscle soreness (DOMS). (2) Thus, resistance training is the stimulus Mr. /Ms. Doe enacts on his/her muscle tissue that results in a medley of physiological responses.
The specific physiological benefits this individual will derive in response to weight training are numerous, such as favorable changes in muscle tissue morphology, enhanced cardiorespiratory functioning, and positive adaptations of the endocrine system. (3,4) Short-term benefits include things like vasodilation of skeletal muscle and improved insulin sensitivity, thus post-workout nutrition is an ongoing field of research. Other benefits are rather concealed and become more pronounced once weight/resistance training becomes a habitual, long-term activity. (5,6)
The take-home point from this section is that intense weight/resistance training acts as a stimulus for muscle tissue, which is subsequently damaged and elicits a range of physiological responses.
Does Nutrient Timing Matter (specifically after training)?
Most gym-goers postulate that post-workout is the most critical timeframe of the day to nourish their body due to the cascade of favorable metabolic and hormonal responses to exercise (especially resistance training). One example being that glucose transport proteins (i.e. GLUTs) are up-regulated in muscle tissue after sufficient resistance training, making your body more efficient at utilizing carbohydrates. (7)
Some nutritionists argue that post-workout nutrition is not a big deal and that total energy/macronutrient throughout the day is more important. When we take a step back and look at the overall hierarchy of proper nutrition, the specific time you eat your nutrients is surprisingly low on the list (at least according to research/literature). However, nutrient-timing (especially after training) is not completely irrelevant.
Even if studies don’t show a significant change in body composition based solely on differing feeding patterns after training, we mustn’t disregard the fact that not taking advantage of the anabolic “window of opportunity” after a workout is analogous to trading in your car for less money than it is worth.
If you don’t have time to eat a solid meal within a few hours after training, then just pack a protein shake and some on-the-go carbs/fats. With that in mind, let’s take a look at specifics for how to get the most of your post-workout nutrition.
Role of Post-Workout Protein
Protein is absolutely essential after training because amino acids (specifically leucine) initiate muscle protein synthesis (MPS). Even in a positive energy state, if cells don’t have the necessary amino acid stores than
MPS will remain inhibited; you can’t build anything without the raw materials that are necessary.
Research thus far has suggests that as long as a protein source contains the necessary leucine content (and other essential amino acids) then there is little difference in MPS between other sources (e.g. milk, animal protein, egg protein, etc). (8,9) Therefore, protein source is important, but only in the sense that the source contains sufficient leucine and essential amino acids. Again, the difference in MPS rates between protein sources is inconsequential if the leucine/essential amino acid content/quantity is enough to maximize the MPS response (see below for quantity recommendations).
Some high-quality sources of protein include: animal protein, dairy (whey & casein) protein, and egg protein. Vegans should aim to get most of their protein through plant proteins like soy and pea protein.
Aim to take in at least 15-20% of your daily protein intake post-workout. For example, most athletes can benefit by eating 1g of protein per pound of bodyweight; so a 180lb athlete should aim for at least 30-35g of protein after training.
Role of Post-Workout Carbohydrates & Insulin
Carbohydrates are on your side when seeking to optimize the MPS to a feeding due to synergistic effect insulin has with amino acids. That being said, insulin is a storage hormone and taking in too many carbohydrates can lead to hypoglycemia and unwanted fat gain.
Your post-workout meal should be a complete meal (i.e. it contains proteins, fats and carbohydrates) so the source of carbohydrates is secondary to total carb intake. The glycemic index (and ultimately, the glycemic load) of carbohydrates is altered when co-ingested with other food sources. For example, eating a complete meal with a high-GI carb (like pure dextrose) will lower the glycemic load of that carb since fiber and fat slow digestion.
This does not mean you need to avoid all simple sugars and high-GI carbs, but it just reiterates the point that “spiking” insulin levels (in the physiological range) doesn’t augment MPS any more than a more moderate rise in insulin seen with lower-GI carbs such as oats, rice, wheat bread, sweet potatoes, and other complex carbohydrates. (10)
Your post-workout carb intake should be about 25-30% of your total daily carb intake. The amount of carbohydrates you should eat will vary based on your specific goals/needs, but a good starting point for trying to build muscle is about 2g of carbohydrates per pound of bodyweight.
Role of Post-Workout Fats
Fats don’t seem to play as much of a role in MPS as carbohydrates and proteins do, but they still serve a purpose in the human diet. Fat is essential for cellular integrity and plays a variety of roles with regards to cellular mechanisms.
Fats come in saturated and unsaturated forms. Diets that are chronically high in saturated fat intake appear to be associated with impaired insulin sensitivity, but unsaturated fat sources appear to have the opposite effect. Due to the overall heart and metabolic health benefits of unsaturated fatty acids, it is recommended to ingest the majority of your fat intake from mono/polyunsaturated sources such as: fish, nuts, and certain plant oils.
The post-workout meal shouldn’t contain much more than 20% of your total daily fat intake, and not more than 25% should come from saturated fat (ideally).