Taking in carbohydrates in the post-workout period has long been seen as an essential component of your muscle-building regimen. The more I research though, the more likely it seems that post-workout carbohydrates will have no impact or may even be counter-productive.
Please note that this advice does not apply to a higher carb diet like the 40/30/30 Glycemic Load approach. For that diet, work out the amount of post-workout carbs needed and stick to it.
First we'll look at the reasons why I've made this decision and then the logical implications following it.
No Benefits To Protein Synthesis
A study shows that the inclusion of carbohydrate in post-workout shake does not increase protein synthesis.
The following study took place in the Netherlands, the subjects being healthy young men. What was great about this study was that it was truly scientific in that it split the men into 3 groups, each ingesting different combinations 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:
- Group 1 - Just protein, no carbs
- Group 2 - Protein with 0.15g per kg of body weight of carbohydrate
- Group 3 - Protein with 0.6g per kg of body weight of carbohydrate
Protein synthesis rates were then measured for 6 hours after training. The results?
- The intake of protein after training increases protein synthesis.
- The addition of carbohydrate (whether in small or large amounts) to this protein did not further increase protein synthesis at all. That may be surprising, but in my opinion it's great news, especially for the carb-cycling MuscleHackers.1
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The Impact Of Carbs On Growth Hormone
Growth hormone levels are elevated after resistance training. It's well known that as insulin levels increase in the body, growth hormone decreases. A large spike in insulin will occur with the ingestion of high GI post-workout carbs. Therefore, it would seem that carb intake after resistance training may be counter-productive.
(I'm still searching for a study in respect to the above point. The only study I could find suggested that carbs AND protein post workout did not blunt growth hormone release. What is needed is an approach similar to the study above which isolates the variables - e.g. would protein ingestion alone have a more favorable impact on growth hormone levels?) Therefore, at the moment, this is intuitive.
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 it's stored fat.
So, What Are The Implications Of This Information?
- It makes the cyclical ketogenic diets easier to follow. Let's say that your daily carb intake Monday - Friday is 40 grams. You now won't lose 5 - 15 grams in a post-workout shake. You can spread those extra carbs throughout the day or have in one meal - e.g. you may feel you benefit from more carbs in you pre-workout meal.
- Increased fat-burning. For the whole of the low-carb period, you now encourage the use of fatty acids for energy.
- Possibly increased growth hormone levels throughout the low-carb period of a carb-cycling bodybuilding diet.
The exclusion of post-workout carbs seems to be a very positive move indeed. If you are worried about depleted glycogen levels, remember that you re-fill these 'storage tanks' during 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.
- Am J Physiol Endocrinol Metab. 2007 Sep;293:E833-E842