A Scientific Review Of Post-Workout Nutrition Data & Application

By Louis Provis

Everyone has their opinion on this one. Some will say carbs and protein; some will say just protein (and just some carbs).

Some will swear by creatine and electrolytes. Many advocate carbs plus EAAs, or protein plus BCAAs, or maybe even just 3g of leucine. As far as timing goes, the post-workout “anabolic window” has always been a topic open for debate.

In this article, we will review the real world, evidence based recommendations of post workout nutrition so you can be confident in your client recommendations. 

What does science say about post-workout nutrition

Before we move into the even more dangerous territory of nutrient timing, let us establish what should, or rather could be included in our post-workout shake. 

PROTEIN

This shouldn’t need explaining; but what is protein; protein builds muscle tissue (that stuff we just broke down in our resistance session), so include it in your shake.

Don’t kid yourself into thinking you can get away with just carbs, because “insulin is more anabolic than protein”; even if insulin were the central player in post workout nutrition, it’s all for nothing if it has nothing to transport.

And don’t think that free-form essential amino acids are going to replicate the effects of an intact protein; they won’t [1].

Okay, so protein. But how much? Well, the piece of research most relevant to this question comes from Moore et al, and gives us the surprising answer of 20g [2].

That seems like very little, I know, but when it comes to maximally stimulating muscle protein synthesis (MPS), there were diminishing returns observable in the study after 20g; 40g achieved the same level of protein synthesis.

It also seems excessively generic to conclude with a number in grams rather than a formula (like 0.4g protein/kg body weight); 20g would thus seem too little for the larger active male, but the subjects in the study weren’t untrained either.

The participants’ weights averaged about 86kg and so if this is a proportional ideal, even a strapping 90kg lifter wouldn’t require more than 21g of protein.

However, as we already know, protein which is evenly distributed throughout the day has the most positive effect on body composition [3].

So with that in mind, it would appear sensible to prescribe the same amount of protein post-workout as we would for every other meal: BW (kg) x 2.2 / # of meals in the day (although daily protein intake is a topic for another day). 

For me, that’s 90kg bodyweight x 2.2 grams of protein / 5 meals = approx. 40g protein per sitting. The extra protein (above the 20g threshold), the study suggests, is used for other functions in the body, not just excreted/wasted.

BUT, if your aim is to stimulate protein synthesis as much as possible, and you feel like you consume enough protein daily to cover the other roles of protein in the body (most probably, if you get geeky about your macros), then consider this.

If your allocated protein per meal is 40g and MPS is maximised at 20g, there is certainly something to be said about splitting your post-workout shake into two.

Borsheim et al’s 2002 paper indicated that a subsequent post-workout protein shake, an hour after the initial drink, elicited a similar level of MPS to the first [4].

Data suggests that thereafter, there is no point “stoking the fire” of protein synthesis any more frequently than 2-4 hours; so why not utilise this opportunity?

However, such an approach overlooks one of the fundamentals of hypertrophy: that the protein that we break down has just as much impact on our physique as the protein that we synthesise.

If the former outweighs the latter, then we’re wasting our time spiking synthesis all day long.

For that reason, and because whey protein speed of digestion indicates that it will induce the greatest protein breakdown as well as the greatest synthesis thereof, such a protocol is worth taking with a pinch of salt. 

CARBOHYDRATES

Next to be considered is the carbohydrate question.

Some would argue that they are not necessary – that an insulin spike is redundant post-workout, or that the insulin secretion, if it is important, achieved by protein (especially isoleucine) is sufficient for stimulating hypertrophy.

In theory that’s fine, but the data says (almost invariably) that ingestion of carbohydrates in the post-workout protein shake elicits the most optimal results; whilst Miller et al’s 2003 study confirmed that amino acids (protein, as we’ve covered) alone stimulated protein synthesis, it also recorded that the effect was amplified when those amino acids were consumed alongside carbohydrates [5].

A similar study, with similar results, interestingly indicated that insulin itself did not positively affect protein synthesis, but where it did prove useful was in the prevention of proteolysis – which the amino acids themselves did not achieve [6].

After all, as previously addressed, net protein synthesis = protein synthesis – protein breakdown, and if the former is being bolstered by protein ingestion and the latter is being inhibited by carbohydrates then YES – we have CHO-PRO synergy, we have protein synthesis, we have greater results.

As a footnote, an earlier study by Bird et al which showed, yet again, that carbohydrate + amino acids resulted in (27%) reduced protein breakdown (compared with placebo rather than EAAs/protein alone, unfortunately) also indicated, more pertinently, that the improved gains were more to do with carbohydrates’ inhibition of cortisol – so, anti-catabolically – than their much-touted anabolic effect, regarding insulin [7]. 

But which carbohydrates ought we use?

Because of the problems with the GI ratings system, and because insulin does not appear to play the greatest part here, your carbohydrate source does not have to be sugar-laden; it can come from anything easily digestible.

If you aim to exercise again later in the day, then restoring glycogen stores quickly might be an issue and fast acting carbs could be a better option.

I would suggest that you won’t have used more than half of your glycogen stores during resistance training and honestly, that glycogen is ridiculously easy to restore over the course of a day –unless you’re on a carbohydrate-restricted diet for whatever reason.

Just get the carbs in (BW (kg) x 0.8-1.0g is a good rule of thumb) and put a stop to that catabolism. With all of that said, one recommendation worth considering is simple and inexpensive: a banana.

Fructose is the post-workout anathema! I hear you cry. Well, not according to Décombaz, who explains that, because the liver favours fructose, it will use the fructose from the banana to restore its own glycogen, thus sparing the accompanying glucose for the muscles, rather than wasting carbs on the liver as we might assume [8].

Dr. Andro over at SuppVersity elaborates: “Preferably, [post-workout] carbs come at a ratio of 2g of muscle substrate (= glucose or precursors) to 1g of liver substrate (=fructose or galactose)” and that a standard-sized banana “with 5g of free glucose and 5g of free fructose (per 100g) [and] 5g of starch, 2g of sucrose and 2.5g of fiber” gives the golden 2:1 ratio of glucose (+starch) to fructose. 

When to consume it?

Now the question of timing – a hot topic in the fitness community – must be addressed. We must first dispel the myth of the 20/30-minute anabolic window of opportunity.

 Now, I don’t often call something a “myth” (there’s rarely smoke without fire), but neither the data nor rational logic can support the theory of such a tiny opportunity within which to make your workout worthwhile.

Tipton et al (2003), for example, found that protein synthesis is elevated for a full 24 hour period after a workout [9], and Phillips et al (1997) collected data to suggest that even 48 hours after training protein synthesis is elevated (by ~33%) [10]. 

Okay, but when is optimal to take a post-workout shake?

Some research has shown that, in the shorter term [11], in terms of protein synthesis (not necessarily the best marker of muscular hypertrophy), waiting for an hour after a workout to take the nutrition on board may be superior to immediate ingestion.

In the long term, however, in terms of actual results (what actually matters, in application), Hartman et al. observed that taking protein within the first hour of the post-workout period did significantly increase strength/size in novice weight lifters [12] – most probably due, we may presume, to the immediate suppression of proteolysis and cortisol-induced catabolism afforded us by the immediate consumption of carbohydrates.

For that reason, there is certainly something to be said for consuming a protein shake soon after thesession is over, but in reality, the difference will be minimal (1-2% maybe).

Don’t cause a traffic accident speeding home after you’ve hit your last rep because you forgot to bring your protein powder to the gym; you will not have invalidated your workout even if your post-workout meal isn’t for a long time. 

Final considerations

FATS

In terms of the energy requirement, post-workout, fats might appear to have a place, especially if carbohydrates are being eschewed for a diet (though, if this is the case, I would have thought that pre-/intra-/post-workout is the time when carbs ought to be consumed).

However, the data on the use of fat post-workout is thin on the ground at present. 

OTHER INGREDIENTS

Dr. Layne Norton’s PHD [13] and further work [14] both indicate the importance of leucine, post-workout and in protein sources generally.

It reported that 3.4g of the amino acid L-Leucine is required to achieve maximum protein synthesis.

So if your post-workout protein source cannot come from a leucine-rich source, then supplementing with straight up leucine may be a good option.

Alternatively, recent research indicates that the same effect can be achieved by making up for the 30% shortfall in the leucine content of rice protein, for example [15], so just increase the quantity of protein if you don’t want the abhorrent taste of leucine powder to ruin your shake.

More hot-off-the- press research suggests that creatine post-workout is ideal, i.e. preferable to pre-workout creatine [16] for strength and size gains, so throw in your 5-10g of creatine then. 

As the research continues to be conducted, more advanced or more well supported protocols can be developed, and the holes in knowledge that we must currently fill with speculation can be filled with hard data.

Until then, this is some of the best data we have to work with, and it shall see us well.