There are two kinds of people in the fitness industry: those that give you advice and motivate you, so that you will buy their product, and those that give you advice, because you paid them for it.
Nah, that’s just the cynic in me talking. Cynicism can be a good thing though: it allows you to be objective. And that’s exactly what I’m going to do in this article. I’m going to give you an unbiased review of the effects of consuming carbohydrates before and after your training sessions.
Should you consume carbs post-workout?
Suppose you consumed a shake containing carbohydrates without protein. This has been researched many times and low doses (e.g. 6g) of carbs do not increase net protein balance after training. Of course, 6g is next to nothing: maybe we just need more to see an effect. Børsheim et al. (2004) tested this. Here, subjects were given either a placebo or a post-training shake containing 100g of maltodextrin.
The result: protein synthesis did not improve, but protein breakdown did decrease, resulting in a significant increase in protein balance. However, the effect was “minor and delayed” and protein balance was still negative. Furthermore, Glynn et al. (2010) demonstrated that 70g of carbs do not influence protein balance more than 30g, so if you’re going to consume carbs, 30 grams should be your upper limit. Glynn et al. also concluded, in their review of the literature, that elevated protein balance as a result of training shakes is almost all due to increased protein synthesis caused by protein ingestion “with minor changes in muscle protein breakdown, regardless of carbohydrate dose or circulating insulin level.” (Emphasis mine; note that they didn’t study casein.) Still, if carbs help reduce even a tiny bit of protein breakdown, that’s better than nothing… right?
In another review of the literature on training nutrition, it was concluded that studies where only protein was administered found increased protein balance “to a similar degree as previously conducted studies that used a combination of essential amino acids and carbohydrate.” Additionally, “a small dose of amino acids after resistance exercise has been found to stimulate similar changes in protein synthesis and protein balance […] with carbohydrate or without carbohydrate.” (Emphasis mine; Kerksick & Leutholtz, 2005). In conclusion, carbs may reduce protein breakdown a little when all you consume is those carbs, but if you already consume protein, carbs have little or no additive effect.
Now, there are two studies (Miller et al. 2003; Bird et al. 2006) that show adding 35g of carbs to 6g of protein increases net protein balance, suggesting carbs may have an additive effect. It is beyond me why this stupid design was replicated several times, but I’ll entertain it here. These studies used the same experimental design as Rasmussen et al. (2000), and the results contradict each other. According to the latter study, “muscle protein breakdown did not change”. The protein stimulated protein synthesis, but the carbs did not increase the effect of protein in any way. Furthermore, the subjects of the Miller study were absolutely brutalized and malnourished. After a fast, they had to do 10×8 leg presses at 80% 1RM and then 8×8 leg extensions at 80% 1RM. That’s like German Volume Training with a higher intensity and reaching failure on every set. Then to ‘recover’ they were given 6g of protein and 35g of carbs. If there’s any situation in which carbs, or anything that gives you some form of energy, can possibly help you recover, it’s this one. And even then only 1 of the 2 studies found a positive, additive effect of carbs.
Koopman et al. (2007) used a much better study design. They examined the differences in protein balance in groups consuming either 0, 0.15, or 0.6 g of carbs per kg of body weight when coingested with ~25g protein after resistance training. Their results? “Whole body protein breakdown, synthesis, and oxidation rates, as well as whole body protein balance, did not differ between experiments. […] In conclusion, coingestion of carbohydrate during recovery does not further stimulate postexercise muscle protein synthesis when ample protein is ingested.”
Staples et al. (2011) wanted to replicate the above finding to end the discussion once and for all. After a weight training session, they gave their subjects either 25g of whey or both 25g of whey in combination with 50g of maltodextrin. They found that consuming 50g of maltodextrin along with 25g of whey does not stimulate muscle protein synthesis or inhibit protein breakdown more than 25g of whey alone.
The most important aspect of the above two studies compared to previous studies was the presence of an at least semi-respectable dosage of protein. So to conclude, carbs only potentially inhibit protein breakdown under extreme circumstances where not enough protein is ingested. Unless you annihilate a muscle with 18 sets done to failure after a long fast and fail to consume more than 6g of protein, carbs don’t add anything to protein.
You may be reluctant to believe this. It’s no fun to find out you’ve been adding heaps of sugar to your shakes for no reason. Conventional bodybuilder theory (read: broscience) is that carbs jack up your insulin, which then helps shuttle all the protein into your muscles. Translated into statistical terms, this means there is a positive interaction effect between protein and carbs on net protein synthesis. This hypothesis is not supported by any research and explicitly falsified by Miller et al. and Staples et al. As with many theories in the fitness industry, it sounds plausible, but the empirical evidence demonstrates it is wrong. Simplistic theories like that do not account for the many complexities of the human body. Your body doesn’t need carbs to process protein. In fact, your body doesn’t need carbs for anything.
Of course, there are some scenarios where carbs can be of use, such as carb-loading (e.g. pre-contest/water manipulation). During a regular bulk though, carbs add nothing to protein. Also, the best diet is always the one that maximizes the amount of beneficial nutrients you take in, given your caloric restraints. Since dextrose, maltodextrin and other nonsense like Waxy Maize Starch are virtually devoid of nutrients and very caloric, they have no place in a good diet. Instead, your carbs should come from vegetables, fruit and foods like quinoa, (sweet) potatoes and oatmeal.
But what about glycogen resynthesis?
Even if conventional workout carbs do not increase protein balance or provide any quality nutrients, they may be needed to preserve glycogen stores, right? First of all, you have to perform an absurd amount of volume to really deplete glycogen stores with weight training. A full-body workout consisting of 9 exercises for 3 sets each at 80% 1RM (something only a beginner can do) only depletes about a third of the body’s glycogen and 9 sets for a specific muscle result in 36% depletion in that muscle (Roy et al. 2000). After performing sets of 6 leg extensions at 70% 1RM until absolute failure occurred (weird protocol I know) and not consuming anything afterwards, 75% of glycogen was restored after 6h (Pascoe et al. 1993). Also, the body regulates itself adequately. The more you deplete glycogen, the faster the glycogen resynthesis. The higher the intensity, the faster the resynthesis. The greater the depletion, the more glycogen the body stores for next time. Even in endurance athletes glycogen resynthesis is often complete within 24h. You’d have to train a muscle twice daily with a volume you could not possibly recover from in order to require carbs to replenish your glycogen in time for the next training session. Should you ever fully deplete your glycogen stores, you’ll know it, because endurance athletes say it feels like being unable to move. Needing carbs for ‘energy’ is in your head.
Origin of the post-workout carb myth
So how come the myth you need carbs in your shakes is so prevalent? There are many reasons.
- Supplement companies want you to believe you need carbs, because carbs are extremely cheap to manufacture. For example, basically all ”˜weight gainer’ products are just sugar sold at a ridiculous price.
- Many people read the carb-only research without realizing that protein makes the carbs redundant.
- The literature advocating carbs for endurance athletes can easily be misinterpreted by people only reading the abstracts.
- Many myths perpetuate themselves, with everyone spreading the word simply because everyone else is also spreading the word. *insert sound of bleating sheep here*
- Many professional bodybuilders inject insulin post-workout. This requires the consumption of a large amount of carbs to avoid going hypoglycemic. Without exogenous insulin and steroids, this is more likely to turn into fat than muscle.
The Verdict on Carbs Post-Workout
You do not need to consume any carbohydrates after your training sessions. When ample protein is ingested, carbs do not have any additive effect on protein balance. You don’t have to avoid carbs, but adding sugar to your shakes is, well, just like adding sugar to any other meal.