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Post-Workout Carbs – Crucial or Counter-Productive?

post-workout-carbsTaking in carbohydrates in the post-workout period has long been seen as an essential component of your muscle building regimen.

But the more I research I do, the more it hits home that adding carbohydrates to your  post-workout shake just has no impact on fueling muscle growth and can only serve to add needless sugar and calories to your diet.

Let me define a couple of terms before we go any further. ‘Protein Synthesis‘ refers to the generation or creation of new proteins. You could think of this as the build-up of new muscle.

Muscle Protein Breakdown‘ refers to the degradation, breakdown, or loss of protein. We actually create this process when we workout, which acts as a stimulus for the body to start building new proteins. ‘Protein Accretion‘ then is the difference between protein synthesis and breakdown. Obviously for muscle-building purposes we want high protein synthesis levels and low breakdown levels for maximum protein accretion rates.

Ok, now we can move on…

First we’ll look at the reasons why I made the decision to ditch post-workout carbs many years ago.

Are Post-Workout Carbs Needed?

(1) Study shows inclusion of carbohydrate in post-workout shake does not increase protein synthesis.

The following study [1] took place in the Netherlands, the subjects being healthy young men.

The study split the men into 3 groups, each ingesting a different combination of protein & carbohydrates. Therefore the only variable was the level of carbohydrate.

Each group performed resistance training for 60 minutes and was given either protein or a combination of protein and carbohydrate each hour for 6 hours after training. The amount of protein for all the groups was 0.3g per kg of bodyweight. The protein and carbs varied as follows:

  1. Group 1 – Just Protein, no carbs
  2. Group 2 – Protein with 0.15 g per kg of body weight of carbohydrate
  3. Group 3 – Protein with 0.6 g per kg of body weight of carbohydrate

Protein synthesis rates were then measured for 6 hours after training. The results?

  1. The intake of protein after training increases protein synthesis
  2. The addition of carbohydrate (whether in small or large amounts) did not further increase protein synthesis at all.

So adding carbs did nothing for protein synthesis. Next…

(2) Another recent study [2] showed that the addition of carbs to a post-workout shake did not change levels of protein accretion at all. A criticism some may have of the above study is that while carbohydate may not help in increasing muscle protein synthesis rates, it may help with decreasing muscle breakdown rates. The following study showed that this is not the case.

whey-protein9 young men trained and immediately afterwards consumed either:

  1. 25g protein alone
  2. 25g protein with 50g simple carbs

As with the above study, the addition of carbs did not further increase protein synthesis rates. Additionally, it was shown that they did nothing to decrease the rate of muscle breakdown at all. Protein accretion was the same with or without carbohydrate.

(3) Impact of Post-Workout Carbs on Fat-Oxidation

In order to keep fat-oxidation (using fat for energy, whether from body-fat or food) at maximum levels, it would make sense to leave the carbs out of your post-workout shake. In doing so you encourage the body to tap into its stored fat.

We want to our post-workout shake to be as fat-free as possible because fat will slow the absorption of protein into the bloodstream. So whey protein in water or low-fat milk with zero carbs is the way to go for maximizing fat oxidation in the post-workout period.

(4) What About Insulin?

Insulin is beneficial in the post-workout period. It helps shuttle the amino acids from our protein into our muscle for repair and growth. The popular thinking is that carbohydrate is required to maximally stimulate insulin release to get this job done. However, this just isn’t true.

Protein alone will cause the release all the insulin you need. A fast-digesting protein such as whey causes a spike in insulin. What the body needs for maximum protein synthesis is the amino acids in protein.

The ingestion of extra carbs (even in high amounts) will only increase the release of insulin by round an extra 1/3rd. But this extra insulin just isn’t required. When the body needs amino acids for growth, and you also get all the insulin you need from protein alone, there is just no good reason to be dumping all that sugar and calories into your blood stream after a workout.

So, what are the implications of this information?

The exclusion of post-workout carbs was one of the most beneficial moves I have made.

It contributes to me being able to stay lean all-year round. It also leaves 200-300 calories per day that I can enjoy in food form later in the day instead of wasting them on sugary water.

If you are worried about depleted glycogen levels, remember that on the GLAD diet, you’ll be consuming carbs in your next solid food meal and start to replace any glycogen lost during the workout.

On MANS you re-fill your glycogen ‘storage tanks’ at the weekend, and you are always free to have a mid-week carb spike if you feel your workouts are beginning to suffer towards the end of the working week.

Ditch the sugar and enjoy your whey :D

Stay Motivated!

Mark McManus

References: [1] Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis. Am J Physiol Endocrinol Metab. 2007 Sep;293(3):E833-42. Epub 2007 Jul 3.

[2] Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Med Sci Sports Exerc. 2011 Jul;43(7):1154-61. doi: 10.1249/MSS.0b013e31820751cb.

Comments on this entry are closed.

  • Mark McManus June 23, 2008, 8:05 pm

    Hi Justin.
    This is based on the fact that insulin aids the transport of creatine into skeletal muscle.
    Actually, whey protein and/or amino acids can perform this job well enough on their own without the carbs.

  • justin June 23, 2008, 7:37 pm


    From what I’ve read, using post-workout carbs greatly increases the effectiveness of creatine monohydrate as a post-workout supplement. What are your thoughts on this?

  • Gazo June 23, 2008, 9:04 pm

    Hi mark
    Will a post work out help repair muscle if requird because my body is feeling rather shredded :). I dont want to miss a training session because secondary muscles are still sore I been eating heaps of fish, meat cheese not so much eggs cooked but I blitz a couple in a blender with a shake in the morning things like that, but i feel my body still needs more so any advise would be great cheers mate.

  • Mark McManus June 23, 2008, 9:10 pm

    Yes a post-workout shake starts the repair process straight away Gazo.

  • Gazo June 23, 2008, 9:17 pm

    Ill have one now then thanks Mark keep up the brilliant work.

  • Dusty June 24, 2008, 1:16 am

    I have also read a study that showed regular whey protein alone, post workout, has been proven to be more effective than whey protein with sucrose or dextrose added. I dropped PWO carbs a while ago. I feel better since I’ve stopped taking them PWO as well.


  • Adam June 24, 2008, 2:48 am

    So final decision is to ditch the workout carbs? And also, should I shift around my meal plan so that the carbs are still split 50/50 for before/after the workout?

  • Mark McManus July 6, 2008, 9:48 pm

    Adam, yes. Suit yourself on this, it’s completely up to what works best for you.

  • Nozza July 11, 2008, 8:37 am

    Since the study, as described, has no control group NOT taking post-workout protein. How does the author come to the conclusion that specific post-workout protein aids muscle synthesis?

  • Chas August 5, 2008, 7:13 pm

    In regards to Post workout Carbs on Friday which would be the day to start the Carb up period. How long after the workout should I wait to start the carb up period?

  • Karan April 25, 2009, 1:38 am

    Hey Mark,

    This looks and sounds great. But what ensures that without carbs throughout the week, that there will be enough energy? I’m a vegetarian on top of that so I am not sure how good MANS will be for me

  • troy June 11, 2009, 9:08 pm

    were you a skinny guy who wanted to build muscle? or an out-of-shape fat guy who lost weight AND built muscle at the same time. do you have “before” pictures?

  • Doug July 15, 2013, 2:48 pm

    What about PWO on a Carb-Up day?

  • Doug July 15, 2013, 2:52 pm

    ….. wait for the next carb meal is the answer, eh?

  • Mark McManus July 15, 2013, 2:52 pm

    @Doug. You can have them. They just won’t do anything beyond what protein alone will do.