I am a loyal Daily Apple reader who’s just begun a full-scale primal + IF + HIIT lifestyle. My only worry is that of muscle loss or impeded muscle growth. As a friend of multiple muscle builders, I’ve been told that carbohydrates are necessary for that muscle growth. While I’m not about to go back to my high-carb ways, I am willing to make an exception for post-lifting meals (within an hour window). I’ve heard this is the optimal time for carb-intake as your muscles are depleted of glycogen stores. I am wondering if you could shed light on this. Is this method actually effective for muscle growth? If so, how many carbs should I consume, and of what kind? And finally, will making this one compromise induce inflammation or impede fat loss?
Thanks to Joshua for the question. It’s a common belief that substantial carbs are required for muscle development. As you say, a post-workout carb boost is often seen as a given. The thinking behind this concept is primarily two-fold. First, as you mention, carbs are touted as essential to refill your glycogen stores – pronto – post-workout so you can be ready to work out again tomorrow. I imagine you’ve also been told that your body will begin to break down muscle if you don’t refuel the glycogen reserves right away. The second element involves the role of insulin. The belief here is that raising insulin levels (as a result of carb intake) will enhance protein synthesis.
I’m here to debunk both of those “truths,” but let me lay out the context for that dispute. First off, let’s be clear that in the Primal Blueprint  we are not just trying to build unbalanced, swollen body-builder muscles; we are looking to maximize strength and our power-to-weight ratio while burning off excess body fat. One of the effects of over-filling muscle glycogen beyond what is necessary is that swollen look, since we store three grams of water for every gram of glycogen. And once glycogen stores are topped off, excess glucose (carbohydrate) is readily converted to fat. Here’s the key: as long as you keep your hard resistance workout at or under an hour (and usually under 35 minutes in the PB model), your body won’t need a lot of glycogen to get through it. I’ve said in the past (and another study  published this month shows) that our bodies can and will restock their glucose/glycogen stores through the gluconeogenesis process using lactate and amino acids. All you really need is a protein-rich snack post-workout for glycogen refueling. Your body can use it to begin refilling its stores, and your normal Primal eating plan during the rest of the day will finish the job. Meanwhile, you’ll cruise through the day nicely relying on your stored fats for fuel.
And that leads us to the other issue of protein synthesis. It’s true that the time immediately after a weight workout is a prime opportunity for protein synthesis. I usually recommend protein in the 30-60 minutes following a workout. (I fast after a workout once in a while to maximize growth hormone – more on that in a later post). For elder apples, protein-rich food may be more effective than a supplement  (e.g. shake). (By the way, I’ll throw out the reminder that a dose of omega-3s post-workout enhances the body’s ability to convert food protein to muscle protein . It’s a good time to pop that fish oil pill!)
As for the common belief that carbs play an integral role in protein synthesis, I hope I can lay that one to rest as well. Researchers at Maastricht University in the Netherlands compared subjects’ blood and muscle samples during recovery when participants ingested a protein supplement to when they were given a protein plus “various amounts” of carbohydrate supplement. The results ? The carbohydrate intake did “not further stimulate post-exercise muscle protein synthesis.” As long as “ample” protein was ingested, the study found, the presence of carbs made no effective difference in protein synthesis.
On the other side of the coin, carb intake can, indeed, negatively impede fat burning by giving the body glucose to use instead of making it work to burn fat. High carb meals that are not consumed directly after workouts will generate lots of insulin. That insulin will promote fat storage once glycogen stores are full, and it will serve to lock fat inside the fat cells. The extra carbs will also contribute to low-level inflammation. Though your metabolism will remain elevated for a while post-workout, you’re essentially done working and burning the same high level of calories. Adding carbs after the fact isn’t necessary, and they come with a price when the body will just end up storing their energy. As I mentioned a few weeks ago, glucose in the bloodstream has toxic implications  unless it’s being stored or burned right away as fuel.
In short, you’re much better off wrapping up your strength workout at an hour or less and staying on the primal track. As long as you go for the protein-rich snack afterward, your muscle growth won’t suffer for it. Of course, any PB-style low level aerobic work can be done for much longer, since you’ll be burning primarily fats anyway.
It’s great to hear from people beginning their experience with the Primal Blueprint. Good luck to you! As always, to everyone, thanks for the great questions and comments. Keep ‘em coming!