To Carb or Not To Carb?

To Carb or Not To Carb?
Do you really need carbs after workouts? Yes and no.

If you've followed any of my diets, you're well aware that I'm a big proponent of using high-glycemic (fast-digesting) carbs such as dextrose (found separately in Post JYM Fast Carbs, as well as in Pixy Stix and gummy bears) immediately after workouts. Of course, you consume these carbs post-workout along with protein as well as creatine, beta-alanine, carnitine, betaine, etc.

Yet some of my diets, such as Super Shredded 8 and Dieting 101, may have you cutting carbs out of your post-workout regimen during certain phases. This has many people worrying about not being able to build muscle without the anabolic benefits of fast carbs. So a question I've been getting a lot of lately is whether or not you need to have carbs after workouts. The answer is yes ... and no. Let me explain.

Refueling Your Efforts

The main reason to consume carbs post-workout is to replenish the muscle glycogen that you burned during the workout. During the workout, your main fuel source is glycogen from the muscles. Glycogen is the storage form of glucose. It is composed of glucose molecules strung together in long strings with numerous branches. The glucose molecules are broken off of the glycogen chain as they are needed to be broken down to generate ATP. Research confirms that the best way to replenish muscle glycogen stores after workouts is to consume high-glycemic carbs as soon as possible after workouts.

Some "experts" argue that during a typical weight-lifting workout, you don't burn up enough glycogen to be concerned about replenishing it. To that I say, "What?!" If you deplete ANY amount of muscle glycogen, you should be concerned with replacing it : especially if muscle growth is your main goal. If a trainer claims that people don't need to worry about replenishing glycogen, then either their workouts are very low volume and very low intensity or they haven't done any research.

The research on glycogen levels during weight training shows that workouts consisting of anywhere from 6 to 20 sets and lasting about 15-30 minutes in length deplete muscle glycogen levels by about 30-40%. Since my workouts last at least 60 minutes and sometimes a good 90 minutes, and you're either moving rapidly between exercises and/or using high-intensity training techniques, cardioacceleraton, Tabatas, etc., then most of my workouts will deplete muscle glycogen levels by a good 60-75%. So, take your carb intake seriously and replenish your muscle glycogen stores Not doing so is cheating your muscles and limiting their recovery.

Research confirms that the best way to replenish muscle glycogen stores after workouts is to consume high-glycemic carbs immediately following the workout. Research shows that when carbs are consumed immediately postworkout, a supercompensation of the glycogen stores is possible. In fact, delaying carb consumption by just 2 hours has been shown to reduce the rate of glycogen replenishment by 50%.

Yet some experts argue that none of this matters for most people in the gym. This is due to the fact that some minimal evidence suggests that whether or not you consume carbs immediately after training or 2 hours later, glycogen levels reach the same levels by 24 hours later. But again, there is minimal and weak evidence to fully prove this. What we are sure of is that high-glycemic (fast-digesting) carbs consumed immediately after the workout replenish muscle glycogen levels the quickest.

Replenishing your muscle glycogen levels as quickly and as fully as possible after workouts is important. Stored glycogen in muscle cells pulls water into those cells. This increases the muscle cell volume and therefore muscle fiber fullness. Given that you gain a muscle pump during the workout, which also increases the amount of water in the muscle cells and therefore the volume of the muscle cells, quickly replenishing muscle glycogen levels can help to maintain a higher muscle cell volume for a longer period. This can be important because evidence suggests that the greater muscle cell volume instigates changes in the muscle that lead to long-term muscle growth.

Consuming carbs, especially high-glycemic carbs (such as dextrose), immediately after an intense workout is also great for making you feel rejuvenated. It can take you from feeling wiped out and lethargic after a brutal workout to energetic and well-fueled. Plus, eating high-glycemic carbs after a workout typically satisfies a massive craving for sugary or starchy carbs without a negative impact on your diet progress. I often recommend gummie bears for postworkout carbs, which most people find very satisfiying and helps them bear through strict dieting the rest of the day.

The Insulin Debate

Another benefit of high-glycemic carbs is the insulin spike that they deliver. While insulin is considered an anabolic hormone, it's role in muscle growth is now much debated. While it was once believed to be a critical factor in instigating muscle protein synthesis and decreasing muscle breakdown, some evidence now suggests that it is not that critical for muscle growth. More critical appears to be the delivery of adequate amino acids from an adequate amount of protein, to the muscle cells.

Only recently has research been done comparing the consumption of just protein postworkout to the consumption of protein plus carbs. That research shows that as far as protein synthesis is concerned, the addition of carbs to a protein shake does not boost muscle protein synthesis, or decrease muscle protein breakdown any greater than the protein shake alone.

Leucine particularly appears to play a critical and direct role in instigating muscle protein synthesis. Plus, leucine has been shown to increase insulin levels. Not quite as high as when carbs are consumed along with a leucine-rich protein source, but adequate enough to maximally encourage muscle growth.

Yet insulin is still important immediately after workouts despite the debate on its direct influence of muscle growth. Insulin attaches to specific receptors on muscle cells. When this happens, it allows for glucose and amino acids, as well as creatine and carnitine, to be taken up by muscle cells. In fact, research shows that both creatine and carnitine are highly dependent on insulin to gain entry into muscle cells and provide benefits. Since you should be taking these two supplements should be taken postworkout, you will want to maximally spike insulin levels if muscle mass is your main goal. That being said, during periods of dieting when you have had to slash all carbs, including postworkout carbs, a postworkout protein shake and BCAAs will adequately spike insulin to drive this supplements into your muscles.

Dextrose: Your Best Bet

Consuming pure glucose after a workout means that the body doesn't need to digest it and it can be absorbed into the bloodstream almost as quickly as it is ingested. This gets a dose of glucose to your spent muscles as rapidly as possible for the quickest and most complete replenishment of muscle glycogen. This will keep muscles stocked with ample glycogen for your next workout. Glycogen also pulls water into the muscle cells, which keeps them fuller and bigger. Maximizing muscle glycogen levels post-workout by consuming ample amounts of high-GI carbs immediately afterward can also help you to keep muscle size maximized.

Fructose Facts

The sugar fructose (50% of the sugar in most fruits, honey, and sucrose or table sugar, is fructose), on the other hand, is a low-glycemic carbohydrate.

Fructose is a form of sugar that the body doesn't really use well. It can't be directly turned into muscle glycogen, like glucose, due to its structure. When you consume fructose -- fruit or high-fructose corn syrup -- it's not absorbed immediately into the bloodstream like glucose/dextrose. Instead, the majority of it must travel to the liver, where it can be converted into glucose and stored as glycogen to be released as glucose when the liver deems it necessary to maintain blood glucose levels.

So fructose is not a great choice to have post-workout as it won't optimize muscle glycogen replenishment. And that is one of the main reasons why I recommend opting for the gummy bears and Pixy Stix versus fruit or most other candy. Most candy uses high-fructose corn syrup or sugar as the main sweetener. Table sugar (sucrose) is about 50% fructose and 50% glucose and high-fructose corn syrup is about 55% fructose or more. Wonka Pixy Stix are sweetened with 100% dextrose and no other sweetener. Most gummy bears, such as Haribo brand, use dextrose and corn syrup. Corn syrup is basically glucose and is very different from the adulterated high-fructose corn syrup.

Why Risk It?!

So why would you risk it and purposely not eat carbs after a workout only to eat them hours later? It's idiotic given that we know that consuming high-glycemic carbs right after a workout is the best and fastest way to restock your spent muscle glycogen. Many people worry that fast carbs after workouts will make them fat. Yet it's the one time of day where you are almost guaranteed that those carbs will not be converted into body fat. And if you're dieting to lose body fat and consuming carbs at any other meals of the day, the last thing that you want to do is nix the postworkout carbs and consume carbs at a different time of day. If anything, cut the carbs from other meals before cutting postworkout carbs.

Maybe you're worried about postworkout carbs because some expert claimed that eating carbs right after a workout can lower growth hormone (GH) and testosterone levels and that a better option is to wait a few hours after the workout to have carbs. After all, it is well documented that eating meal, particularly a carb-rich meal, lowers growth hormone levels. There is even a new study showing that the consumption of high-glycemic carbs lowers testosterone levels. However, the recommendation to forego carbs immediately after workouts to prevent a drop in growth hormone and testosterone levels is severely flawed. Why? Because growth hormone and testosterone levels peak during the workout and when the workout is over they rapidly plummet. Growth hormone and testosterone levels are going to fall after a workout regardless of whether or not you eat anything. So eat up after workouts and stop worrying about your already plummeting hormone levels.

Jim's Take-Home Points:

To truly maximize muscle recovery and growth, your best bet is to consume fast carbs along with protein immediately after workouts. There's really no debating how well this strategy works in the real world. Skipping carbs after a workout to prevent a drop in hormone levels, or because they don't increase muscle protein synthesis, is silly if you're eating carbs at other meals. The post-workout window is the best time to maximize the utilization of those carbs, and it helps with the utilization of other supplements that you should be taking post-workout (i.e., creatine and carnitine).

The only time that you should cut carbs from your post-workout meal is when you have slashed all carbs from your diet, except for the small amount in vegetables and protein powders, etc. But this is only when fat loss is your primary focus. The good news is that even without carbs, muscle protein synthesis will not be compromised and even insulin will have a good spike, as long as you consume a protein powder (the addition of BCAAs will enhance that as well).

Immediately after workouts, shoot for about 40 grams of protein from a mix of whey and casein (as in Pro JYM) to maximize muscle protein synthesis. Consider adding 5-10 grams of BCAAs postworkout (Post JYM Active Matrix contains 6 grams) to ensure maximal protein synthesis and to further boost the insulin spike. This is especially important if you are in a "no-carb" post-workout phase of your diet. When you are consuming carbs, go with about 20-60 grams of high-glycemic carbs depending on your weight, goals, and the intensity and duration of the workout. If you find that a big dose of high-GI carbs leaves you feeling lethargic, then have a smaller dose of high-GI carbs (15-30 grams) and follow it with a small dose of low-GI carbs (15-30 grams), such as fruit, oatmeal, sweet potato, etc. During phases of your diet where you are slashing all carbs from your diet and need to skip post-workout carbs, take 40 grams of a protein shake and 5-10 grams of BCAAs. This will keep you anabolic, despite being low carb.

 

References

Robergs, R. A., et al. Muscle glycogenolysis during differing intensities of weight-resistance exercise. Journal of Applied Physiology 70:1700-1706, 1991.

Essen-Gustavsson, B. and Tesch, P. A. Glycogen and triglyceride utilization in relation to muscle metabolic characteristics in men performing heavy-resistance exercise. European Journal of Applied Physiology 61:5-10, 1990.

Tesch, P. A., et al. Muscle metabolism during intense, heavy- resistance exercise. European Journal of Applied Physiology 55: 362-6, 1986.

Ivy, J.xL. Glycogen resynthesis after exercise: effect of carbohydrate intake. Int J Sports Med. 19(Suppl 2):S142-5, 1998.

Staples, A. W., et al. Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Med Sci Sports Exerc. 2011 Jul;43(7):1154-61.

Koopman, R., et al. Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis. Am J Physiol Endocrinol Metab., 293(3):e833–42, 2007.

Casagrande Figueiredo, V. and Cameron-Smith, D. Is carbohydrate needed to further stimulate muscle protein synthesis/hypertrophy following resistance exercise? Journal of the International Society of Sports Nutrition. 10:42, 2013.

Caronia, L. M., et al. Abrupt Decrease in Serum Testosterone Levels After an Oral Glucose Load in Men: Implications for Screening for Hypogonadism. Clin Endocrinol (Oxf) 78(2):291-296, 2013.

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