Preface: Is Low-Carb Really Best for Body Re-Composition?
Introduction by Lonnie Lowery, PhD
Low-carbohydrate diets have certainly received their share of attention in recent years. While the popularity of Atkins, South Beach, and other low-carb diets peaked last year, it remains an interesting topic among physique athletes.
In the scientific community, research is continually published, whether low-carb popularity with the lay public wanes or not. A recent meta-analysis (study of other studies) suggested that lower-carb, higher protein diets are indeed best for body re-compositioning (Krieger, et al., Feb. 2006).
Of course, differences in opinion do occur regarding how to best derive the metabolic benefits of lower-carb (or even very-low-carb) diets. But, I think readers will agree that this collection of experts will echo at least some of their existing beliefs as far as how much carbohydrate is too much and how much is not enough.
So without further preface, let's take a look at this commentary that Greg has assembled for the benefit of your brains and your love handles.
– Lonnie Lowery, PhD
T-Nation: We have a big group here so let's jump right into it. How do you define the term "low-carb nutrition?"
Charles Poliquin: I consider low-carb to be when the daily carb intake is below 0.25 grams per pound of bodyweight. In other words, a 200-pound man ingests only 50 grams of carbs per day.
Dan John: Well, as simple as that question sounds, that's the big issue. I've talked with people who think switching brands of cereal is a "low-carb" decision.
Personally, I like to start with a simple proposition to most athletes: zero carbs. If we have to make body comp changes quickly, well, there are no carbs allowed. We know that there are also no "essential" carbs, so the first hurdle we have to deal with when it comes to the athlete is this: fat phobia.
When athletes hear "low-carb" or "zero-carb," they immediately try to figure in "no fat" too. Madness, I tell you. If you read Clarence Bass's original Ripped, he went no carb and no fat. That isn't the idea. One egg white a day and a twice-baked piece of chicken is not my idea of an athletic diet.
The first thing I encourage my athletes to do in the zero-carb approach is to think "feast." Eggs, cream in the coffee, and meat for breakfast followed up with a snack of ribs. Eat a lot. Drink a lot of water, too. Here's something I strongly recommend, but I can't get my athletes to do: sip on a little olive oil every so often. Yep, sip it, like a good Scotch.
Meat, fish, fowl, and eggs, that's the ticket. My athletes are amazed on day three when they get a good night's sleep, their joints are feeling good, and they notice an "ease of passage" in their daily movement.
So, that's zero carb basically, so what's low-carb? To some, anything under 95% of the day's calories from carbs is low-carb. Really, I like the strictness of the Atkins Diet and its copies: 40 grams a day. Others slide up to 100 carbs a day, but already we're getting into problems.
Like what? Low-carb cereal, low-carb bread, low-carb ice cream...you know the drill. Here you go: eat meat and veggies at first. Now, a hand from the back goes up: "What about fruit?" My challenge to Americans: get fat on fruit. I challenge you! Eat 300 plums a day for two weeks and get back to me. (For the idiots out there: I'm joking!)
Joel Marion: I think the issue arises when people fail to differentiate between the terms low-carb and ketogenic. The terms are often used interchangeably, especially within bodybuilding circles, but the latter is much more specific than the former.
The term "low-carb" really is an ambiguous, almost relative term. For example, you may consider a diet prescribing only 150 grams of carbs "low-carb" while to someone else such a "high" carbohydrate intake doesn't come close to qualifying for the title. You'll even see the term "lower-carb" used for a lot of these diets that restrict carbs while still being much less strict than something like Atkins. Then you have "very low-carb" and "no-carb," which further bring confusion to what exactly is meant by each one of these terms.
Now when you're talking "ketogenic," you're looking at much more specific parameters. You're not on a ketogenic diet unless you're in ketosis, so at least that gives dieters somewhat of an absolute to measure. While there are exceptions, the majority of people will have to stay under 50 grams of carbohydrates per day to reach and stay in ketosis, some an even lower threshold.
Also, if ketosis is the goal, protein intake should be set around .8 to 1 grams per pound of lean body mass, but not higher. Reason being, even if carbohydrate is severely restricted, a high protein intake may keep you from reaching ketosis due to gluconeogenesis, or the conversion of protein to glucose within the body.
T-Nation: So how do you know if you're really in ketosis?
Joel Marion: Well, you'll have to monitor the amount of ketones present in your urine with ketostiks.
That said, whether you reach ketosis or not isn't really going to matter from a fat loss standpoint. All else being equal (which it never is in the real world), you should expect similar fat loss from someone consuming 40 grams of carbs daily who's non-ketotic and someone consuming the same amount of carbs who indeed is in a state of ketosis. It's more a matter of energy balance, which has been said time and time again.
So what's "low-carb?" If by low-carb you mean "ketogenic," then we're probably looking at less than 50 grams of carbs daily. I think the terms "very low-carb" and ketogenic will leave you around about the same spot: less than 50 grams of carbs daily.
No-carb is pretty self explanatory, although not very realistic. Then you have "lower-carb" which could be anything significantly above 50 grams all the way up to a carb intake of one gram per pound of lean body mass. Anything higher than one gram per pound and we're entering "moderate carb" territory. (Oh look, another term!)
T-Nation: Okay, let's let Cassandra chime in. For those who don't know, Cassandra has a fitness/figure background, a Master of Science degree in nutrition, plus she's working toward her PhD, and she's barely into her mid-twenties! Take it away, Cass.
Cassandra Forsythe: While I've been working at UConn researching very-low-carbohydrate ketogenic diets (VLCKDs) with Dr. Jeff Volek, I'd define a low-carbohydrate diet (LCD) as one supplying less than 50 grams of carbohydrate per day, or providing less than 10-15% total energy from carbohydrate (i.e. a 3000kcal diet with 10% calories from carbohydrate would have 75 grams of carbohydrate).
To go a step further, I'd classify a VLCKD as one supplying less than 20 grams of carbohydrate per day from only non-starchy vegetables (leafy greens) and causing the body to produce ketones from dietary fat which are detected in the urine by reagent strips (those ketostiks that Joel mentioned).
Some people also define a LCD as one that provides less carbohydrate than recommended by our nutritional governing bodies (AHA, ADA etc.). This would mean that any intake with less than 55% total energy from carbohydrate is a low-carb approach.
I'd somewhat agree, but modify it to say that diets with less than 35-40% energy from complex carbs and vegetables (no Gatorade here) are a type of LCD. Zone and South Beach diet plans would thus be included in the definition of low-carb.
The foods eaten on a LCD can include low-carb products (bars, shakes), but should come mostly from whole-food sources like red meats, eggs, fish, poultry, cheese, leafy vegetables, oils, nuts, nut butters, avocados, and gelatin. Fruits are acceptable in small quantities and so are some beans and legumes.
On a VLCKD, carb restriction is more extreme (no fruit at all) and fat intake has to be high. Fat should provide at least 60% of total calories, and must come from animal fats, oils, creams, egg yolks, and fatty fish. Fat can't come in large quantities from any higher-carb fat sources like avocados, nuts, and seeds because these limit ketosis.
Low-carb products should be almost completely avoided. I've seen many subjects in our VLCKD studies become knocked out of ketosis just by eating a low-carb bar, shake, or candy. There seems to be more impact carbohydrate value from low-carb products than one assumes.
Protein can't be too high because of gluconeogenesis, but is important to preserve lean muscle during weight loss. Truthfully, a VLCKD is difficult for many people to follow for a very long period of time. But, the restriction is useful (and necessary) to initially kick-start fat metabolism by up-regulating fat pathways and enzymes. This "rapid ignition" seems to last for quite some time, even while reducing the strictness of the diet, just as long as carbs don't drift up too high.
The leaner you are, the more carbs you can eat. Also, a VLCKD isn't for everyone because of its food limitations, but a LCD is beneficial for most people. Ketosis isn't necessary to reap the rewards of decreasing carb intake.
Today's society is carb-crazy because we're surrounded by a plethora of carbohydrate-rich foods. It's just too easy and inexpensive to grab a carb-laden food versus something high-protein (beef jerky) or high-fat (nuts or cheese). Plus, some scientists have driven the "fat is bad" and "protein will ruin your kidneys" mentality so far down our throats that we have a hard time swallowing any other info.
No matter how you define a low-carb nutrition approach, cutting back on carbs in one form or another will have numerous positive effects for your health and your body composition.
T-Nation: Dave, lay your definition on us, then we'll move on.
Dave Barr: Define low-carb nutrition? How about I give the super scientific answer, you know, the one that's so esoteric no one understands (and therefore can't use)?
No, no, I'm getting sick of that. I'll give a simple pragmatic answer instead: a diet consisting of an insufficient quantity of carbohydrates to meet daily energy requirements, such that dietary and body fat must be used as the primary energy source. The concept is DiPasquale-esque because he's the pioneer in this field.
T-Nation: Okay, clearly, "low-carb" can mean a lot of different things to different people. Next question, what are some advantages and disadvantages to a low-carb nutrition plan? Danny?
Dan John: Well, it depends on the approach. Listen, if you take the whole "low-carb bread and cereal" approach, there are no advantages. You end up with the same issues. What issues? Well, if what I read is true, the bulk of Americans struggle with grains at some level, milk at some level, and sugar at a really "fat ass" level.
Shopping on a true low-carb diet becomes easy. Here you go:
Not a bad shopping list.
The disadvantages of low-carb? Well, you have to skip the prepared food island usually, the fast food aisle, the breaded meats world (who came up with that, anyway?) and save a ton of time shopping. You never have to look at the side of a package to determine if a "serving size" is one scoop or half a can or whatever formula they use to come up with "low fat" versus "no fat."
Dining out can be a problem. It's become easier, but most places cater to people who think deeply breaded and deep fat fried onions to be a member of the food family.
The biggest advantage is ease of shopping and deciding on meal selection. The biggest disadvantage? You have to cook practically every meal, either in one big cooking day on Sunday or throughout the week.
The fat loss and the improvement in every other area of life doesn't seem to be as important as convenience. It sounds crazy on paper (or bytes on a screen), but I'm telling you, it's true.
Dave Barr: The longer I stay in the game, the more I come to understand the importance of psychology. It's in this area that low-carb diets have a major disadvantage. Having our muscles flatten out, the feeling of lethargy, and the lack of sweet tasting foods can all take their toll on someone who's unaccustomed to low-carb eating.
Drastically reduced food selection is probably the main disadvantage, and this has caused many people to abandon the diet in favor of a lower calorie, moderate carb version. Having said that, the feeling of carb-ups is an incredible reward for a week of strict eating. The way that noobs claim to get off on arginine supplements, you'd think they'd be all over a diet that provides an even more powerful feeling.
Another big plus is that you're more likely to add muscle while maintaining a state of fat loss. In other words, calories can be higher while still losing fat. Of course this doesn't compare to actual bulking and cutting cycles, but for those who feel the need to do both at once, low-carb is the best option.
Charles Poliquin: There are many advantages to low-carb nutrition; that's why I tend to use it with about 75% of my clients. But it's not for everybody. Some genotypes do very poorly on it, and the extent of how badly they do on it is a function of the time they're on it.
Before you look at the advantages and disadvantages, as Jonny Bowden would say, you need to approach your fat loss system like you should approach relationships: daily attention. Nurturing, support, crisis management, intervention, focus, consciousness, and mindfulness... It requires good negotiation skills. All the things we don't tend to have when it comes to food.
Advantages to a low-carb approach: It promotes muscle gains while reducing fat stores.
I'm not a believer in the bulk-up/get lean approach in hypertrophy training. For 75% of the population, I strongly believe that if you want to gain lean body mass while losing fat, the low-carb approach will do it better than anything, especially if you're taking supplements that enhance insulin sensitivity. Because insulin sensitivity tends to improve on low-carb diets, fat loss is more sustained with this approach.
A low-carb diet is also very valuable in treating dyslipidemia. It's particularly effective at reducing triglycerides and VLDL. It has a significant effect also on reducing LDL. Its effects on raising the good forms of cholesterol aren't as drastic, but overall, a low-carb diet improves the HDL:LDL ratio in a manner that significantly reduces cardiovascular risk.
Though for somepeople cholesterol may go up on a low-carb diet higher in fat, research shows that when you look at the actual subdivisions of cholesterol, the better, less athrogenic fractions improve and the more athrogenic fractions decrease. For example, even within LDL ("bad" cholesterol) there are different types: LDLa and LDLb. The LDLb is the bad stuff, and this tends to diminish even if the overall LDL goes up a bit.
A low-carb diet can even reduce inflammation. Many patients will report reduced joint pain while following a low-carb diet. High insulin levels are correlated with inflammation markers. Since the insulin output is lower with low-carb diets, it makes sense that inflammation would decrease.
Though there have only been a couple of studies on this, the ones that have been done are very promising and do in fact show reduced inflammation. Anecdotally, many people on low-carb diets who have arthritis or joint pain report a decrease in symptoms. Another cardiovascular risk marker, Hs-CRP, goes down very quickly when a low-carb diet is followed.
Another advantage: improved glycemia and insulin levels. Blood sugar management is probably one of the biggest benefits of low-carb diets. About 68% of American are pre-diabetic. Insulin is the hormone of aging and inflammation. Managing insulin is one of the best ways to promote health and longevity.
Then there are the positive effects on blood pressure. Because low-carb diets reduce inflammation, improved blood pressure is a direct benefit of low-carb dieting. Remember, too, that insulin has other functions besides storing fat. One of them is to tell the kidneys to hold onto sodium, so it's no surprise that blood pressure frequently drops on a lower carb diet, sometimes faster than a porn star's panties on the set of a VIVID movie.
Finally, low-carb diets can provide greater energy. Now, before all the armchair experts lash out and rush out to burn Canadian embassies, hear me out. Greater energy is indeed a very common report of low-carb dieters.
Psychometric tests always report greater well being of the patient after this dietary approach. It probably has more to do with the better management of one's glycemia. As Robert Crayhon says, if you want more energy, take care of your mitochondria. Lower insulin levels help with mitochondria's energy producing capacities.
T-Nation: That's a pretty convincing list, Charles. Any disadvantages?
Charles Poliquin: Sure. Low-carb nutrition tends to be bland. However, there are plenty of resources (such as books like Living the Low-carb Life by Jonny Bowden) that provide you with a wealth of cooking tips.
Food prep time is greater too. Since the meat content is greater, more time is needed to prepare the food. As simple as cooking a steak is, it takes more time than making a sandwich. But again, there are solutions.
Constipation is often an issue too with low-carb dieters. That can be off-set by taking in a mixture of ground flax seed hulls and ground fenugreek seeds first thing in the morning. Besides providing the body with many forms of fibers, it detoxifies xenoestrogens and improves insulin sensitivity.
Finally, there's a possibility of developing certain nutrient deficiencies. Because one abstains from certain foods, I recommend to all my patients to take a quality broad nutrient multi-vitamin supplement. This goes along with a varied plan of antioxidants that changes every eight days. I basically change the nature of multi-antioxidant products. To make it simple, I change the color of the anti-oxidants.
For example, the first product may have five or six different flavonoids like limonene (so the base color is yellow); the next eight days we switch to purple so we use a formula that has grape seed extract, bilberry, etc.
T-Nation: Interesting stuff. Cassandra, what advantages and disadvantages do you see?
Cassandra Forsythe: As Charles mentioned, the primary advantage of the low-carb approach is that you improve insulin regulation. By having more stable insulin levels, you protect your body from developing insulin resistance. This protection occurs because you eliminate constant insulin stimulation in response to frequent carb consumption. By controlling insulin, you create a hormonal environment that favors fat oxidation, which has important implications for health, body composition, and athletic performance.
First, from a health perspective, when there are fewer swings in insulin, your body is better at processing fat, which reduces your risk factors for developing cardiovascular disease and diabetes. For heart disease reduction, controlling insulin helps shift the concentrations of fat-carrying lipoproteins in your blood to more beneficial lipoproteins (HDL) and less harmful ones (LDL). All of the research to-date investigating low-carb approaches have shown that even without weight loss, concentrations of HDL cholesterol (the good cholesterol carriers) are increased, while concentrations of triglycerides (the harmful fat carriers) are decreased.
With respect to diabetes, a low-carb approach is shown to reduce fasting glucose, increase insulin sensitivity, reduce hemoglobin A1c (a long-term marker of diabetes) andimprove kidney function (seen by doctors who measure urine micro albumin levels. Surprise, surprise!)
Second, from a body composition perspective, the answer is clear: more fat oxidation will eventually lead to less total body fat! Third, from a performance perspective, both intramuscular triglyceride (fat stored in the muscle) and adipose fatty acids can be used as an energy source to support activity. But, they're only used sparingly when carb intake is high.
As someone adjusts to a low-carb nutrition approach, they increase the activity of enzymes that allow fat to be brought into the mitochondria of muscle cells so it can be broken down for energy. For athletic people (and even non-athletic people), this means that fat plays a more important role than normal, and performance activity is sustained.
T-Nation: And the disadvantages?
Cassandra Forsythe: It's hard for me to speculate the negative aspects of eating low-carb because there just so many positive benefits of adopting this type of nutritional pattern!
I think when people hear "low-carb" they automatically envision eating tubs of lard and plates of scrambled eggs. To the contrary, "low-carb" really means "controlled smart-carb." It means that our habitual comfort foods like pasta, cookies, muffins, bagels, cereals, and sweets must be avoided, which may be considered a disadvantage for some people.
Since we just talked about foods contained in a low-carb diet, I won't reiterate. Instead, I'll have to say that one of the main disadvantages of a low-carb nutrition approach is that until you really understand what "low-carb" means (basically that there's a lot of variations to low-carb and you can choose the one that suits your needs), you'll be skeptical of trying it. You'll believe all the negative comments made about this type of eating style and you'll have a hard time changing your negative misconceptions towards both fat and protein.
If only that dinner of marshmallows and Cheez-Its didn't taste so good, we might all be able to kick the idea that high-carb diets are healthy!
T-Nation: Okay, Cassandra makes me want to go low-carb year 'round! Joel, I think you have a different perspective though.
Joel Marion: With regards to advantages and disadvantages, the former are few and the latter many in my opinion. While very low-carb diets may have their place for very short periods of time, they aren't a solid long-term approach or even an ideal way to lose fat. Yeah, you'll see the scale shoot down rather quickly, but what's really happening? A lot of water and glycogen loss, some lean tissue loss, and very little fat loss.
For instance, you may have someone experience a 12 pound loss on the scale over a two and a half week period of very low-carb dieting, which is at least initially pretty impressive. But then consider that 7.5 pounds of that was water, one pound glycogen, another two pounds muscle, and the remaining 1.5 pounds fat. Only 13% of the weight lost was fat. Not exactly impressive.
Very low-carb dieting is quite good at giving individuals a false sense of results, especially early on in the diet, which is where the problem starts. They experience initially enticing results which causes them to want to continue on with a very mediocre approach to dieting.
False sense of results aside, there are other, bigger issues, a major one being the effect of low-carb dieting on leptin, a hormone in which circulating levels are highly associated with that of insulin. Leptin is a regulatory hormone that communicates with the hypothalamus and basically gives the body the "yea" or "nay" to utilize adipose tissue for energy. Under normal conditions, leptin is abundant and binds freely to its associated receptors. The receptors then send a message to the brain to assure it that things are in good shape.
Now, when dieting (especially with diets in which insulin levels are chronically low, i.e. very low-carb diets), leptin levels are low and consequently there isn't as much binding occurring. The receptors recognize this and inform the brain as to what's going on. From there, the brain begins to send out various regulatory signals to the rest of the body, causing a decrease in thyroid output and metabolic rate and an increase in the catabolic hormone cortisol, along with appetite.
Very low-carb diets (again, diets in which circulating insulin is low day in and day out) end up exacerbating all the metabolic adaptations that occur when restricting calories by further screwing with leptin levels. In the end, very low-carb diets are no more effective from a fat loss standpoint than their higher carb counterparts. This has been shown time and time again in the research.
That brings me to the last point I'll make here, and perhaps the biggest strike against the low-carb diet: the approach's extreme impracticality. In order to adhere to such a regimen, individuals must fight – on a daily basis – not only the general cravings associated with calorie restriction, but also intense carbohydrate cravings for foods that they should be allowed to eat.
To say that dieters aren't permitted to enjoy foods such as pasta, various potatoes, whole grains, many fruits and vegetables, legumes, etc., is both impractical and unnecessary. Practicality comes down to sacrifice (investment) vs. results (return), and unfortunately the low-carb diet is unable to produce the necessary results in order to counterbalance the immense sacrifice required. I could see if results were extreme, then to some it'd be worth it; however, results really are average at best, and better than average results are achievable with approaches that require much less sacrifice.
All that said, I do use the approach with clients, but only for very short durations. And by very short durations, I mean one or two day spurts at strategic points during a diet. Actually, that's not entirely true. I'll start most diets off with a week of very low-carb dieting because at that point I actually want to cause a quick crash in metabolism and hormone levels and there's no better way to do that than a very low-carb diet.
T-Nation: Okay, when most people throw the term low-carb around, they're usually in a fat loss phase. Seldom do you hear a low-carb approach discussed when someone is placing their primary focus on hypertrophy and strength. What are your thoughts on a long term, low-carb approach for a weight trainer whose primary objective is muscle gain and/or maximal strength development?
Dave Barr: To reiterate, there's no substitute for bulking and cutting cycles. Everyone wants to add muscle and lose fat simultaneously, without giving any thought to how our bodies work. It just doesn't make sense for the body to expend energy producing a tissue that's going to expend even more energy (i.e. muscle), while our actual energy intake is reduced. This contradicts every survival mechanism we have.
Having said that, I believe that we can slightly override this survival mechanism by keeping our carbs low. This will help us add muscle with a reduced chance of adding body fat.
As far as the best method for strictly adding muscle, I have a strong preference for a "see food" diet. Unless you're fat phobic or a FFB, there's not a great reason to limit yourself with regard to any nutrient when bulking.
Bottom Line: For people who add body fat easily, low carb diets are great. Otherwise, it's best not to limit yourself.
Dan John: This is where you start getting into even more trouble. Are we talking simply low-carb, or The Zone, or Paleo? Once I moved into the direction of Paleodiets, I found that a bunch of other good things began to happen.
I read back in 1979 that 95% of Americans either had trouble with wheat or milk. I mentioned this to a "diet major" at Utah State and she said, "That's stupid; they even have wheat in milk shakes." I thought to myself, "What an odd argument. If something makes you sick, shouldn't you avoid it?"
So, if Dave is right and we need bulking cycles, but we bulk up with foods that are holding us back, then... I don't know here. I've rarely found that simply adding weight had much to do with performance. In fact, I find it has never made me throw farther or lift more (save the squat). So, if you're a lean, mean, fighting machine and improving performance on a low carb diet, why go off it to bulk up?
This is one of those questions that seems simple, but there are lots of people trying to figure it out. In performance sports, where you have a distance or weight or whatever, it's hard to unpack one factor, even one as important as eating, and figure out if it hurt or helped. So, it's exactly what I said about the " One Lift a Day" Program: it worked so well I stopped doing it.
If low-carbing makes you feel better, look better, and perform better, well then, drop it by all means and start eating as much wheat as you can stuff in your mouth! Or don't.
Charles Poliquin: Long term, the goal should be to improve insulin sensitivity so that you can eat more carbs without disrupting glycemia, lipid profiles, blood pressure, etc.
Insulin is the only hormone we have control over. By opposition, endogenous production of reproductive hormones is much more challenging, yet when controlled it can shred up a physique and pack on lean tissue.
My male clients will attest to this: it's rather simple (I did not say "easy") to stay at 6% body fat or less when you manage your insulin wisely. Again, it has to do with the genotype of the individual, but I strongly believe that after six months of a great diet and supplement program, carb intake can be increased progressively without any negative impact on health markers. The key is to choose your carbs wisely.
Most of the world population is carb intolerant. Only 25% of the population is carb sensitive. The most important type of carbs to eliminate for carb intolerant individuals are grains, particularly the ones containing gliadin. Our clients who are carb intolerant lose impressive amounts of body fat by adhering to a gluten-free diet. That means eliminating all wheat containing products, even soy sauce.
T-Nation: Cassandra, what are your thoughts on low-carbing when pursuing muscle gains?
Cassandra Forsythe: Hypertrophy and strength aren't hindered when carbohydrate intake is limited. That's a common thought, but is just not true, nor holds any substantial evidence. Hypertrophy and strength gains are staled when your energy intake is too low. You can eat a LCD and still excel in the weightroom just as long as you're eating enough food.
Like we said, people often use a low-carb approach to lose weight. This means that while they follow this eating pattern, they also restrict calories. When you don't eat enough food to support your normal daily activities, let alone weight training (as is often done in most weight loss diets), you obviously jeopardize muscle growth and function no matter what the macronutrient composition may be. Therefore, eating low-carb isn't a limiting factor for hypertrophy and strength.
Interestingly, as Dr. Lowery has pointed out several times in his explorations of protein, a higher than normal protein intake helps protect muscle tissue when energy balance is compromised (i.e. during heavy training weeks). So, it makes sense that a LCD providing enough energy to promote weight training and athletic goals is preferable over a low-fat, low-protein diet normally promoted as the ultimate diet that all athletes should follow.
Joel Marion: Again, the answer to this question is going to depend on exactly how you're defining "low-carb." You'll have some strength coaches touting the results they get with clients using a low-carb approach and then come to find out their clients are actually consuming quite a bit of carbs but only within the "post-workout window." The approach being used here is one of nutrient timing, not low-carb nutrition.
But assuming that we're all finally on the same page talking about the same thing here (very low-carb, ala Atkins), I'll address the question. Is low-carb dieting an optimal nutritional approach for gaining muscle mass? Not even close. The reason you don't hear many people touting "low-carb" as the dieting approach best suited for gaining muscle is the same reason you don't see anyone in the know recommending sets of 8-12 to increase max strength – it ain't gonna work.
Insulin is key to initiating an anabolic response to resistance training; this has been shown time and time again in workout nutrition research and anecdotally with individuals who've appropriately implemented a workout beverage such as Surge. The carbohydrate (CHO) only group does better than the water group, and the EAA (essential amino acids) + CHO group does even better. We've all seen the nifty graphs.
And while a fair amount of protein synthesis will occur with an EAA-only administration (no carbs), EAA + CHO still wins the prize. Point being, better results are always going to be obtained when inviting our friends carbohydrate and insulin to this potentially very anabolic party – the workout nutrition window.
And why would you not include carbs? Are you afraid about fat gain as a result of their ingestion during this time? If so, you're worrying about a non-issue. Insulin sensitivity is peaked and muscle tissue is hungry for carbohydrate during and after a resistance training session. Unless your training stimulus is inadequate (i.e. you just did a half-assed workout and are trying to get away with a truckload of carbs after) or you're going way overboard with the carbs and calories during this time, the probability of things spilling over to fat storage isn't very high.
And this increased insulin sensitivity doesn't all of a sudden terminate immediately following the uptake of the nutrients in your post-workout shake. We're talking a couple of hours here, so you have time for a couple of carb-containing meals in addition to your workout beverages.
Skipping out on the carbs around a resistance training session for fear of fat gain is just plain stupid. You have nothing to lose by including them, and much to gain. When nutrient timing is properly implemented, this whole carb intolerance thing is extremely overblown.
Note: In Part II, the contributors will discuss low-carb diets for competitive athletes, carb cycling, and much more! Stay tuned!