Trygve.Com > MFW > Nutrition > "Comparing the Diets" - Lyle McDonald
nutrition food protien Subject: Comparing the Diets, Lyle McDonald
From: Lyle McDonald <>
Date: 2003/12/20

Ok, since the book project this was originally written for is unlikely to ever get done, I figured I'd post it. It's a long (11 pages) chapter/piece examining the pros/cons of the major dietary camps (high carb/low-fat, moderate carb/moderate fat, low carb) and which diet (IMO, of course) might be most appropriate for a given individual. It's done in my usual anal-compulsive style and covers pretty much all of the bases (with the possible exception of the counting calorie vs. not counting calories situation although I may add that). The chart at the end will probably look fucked up (and there are a lot of typos including my apparent inability to type carbohydrate correctly). Enjoy (or don't).


Comparing the diets

In this chapter, I want to look at each of the three major dietary camps and examine some of the variables which go into determining which diet might or might not be appropriate for a given individual or set of circumstances. By the end of this chapter, you should have a reasonable idea of which diet approach may be appropriate for you.


While trends are beginning to show shifts, the high-carb/low-fat diet is arguably the de facto standard recommendation for health, weight loss and athletic performance. At the same time, it's becoming more common to criticize this diet on various grounds, blaming it for increasing obesity and health problems among the general public. Research is finding that, among certain populations, such a diet can do more harm than good. Among more fringe diet groups, a diet based around high-carbs and low-fat has become an almost unspeakable evil. Claims that you can't lose fat on high carbs or can't get ripped, or whatever, are becoming more and more common.

Now, if you still think of me as the keto-guy you're probably expecting me to shit all over this diet interpretation or take the fringe stance on it. With some qualifications, I'll say up front that you're wrong. The reality is that there are plenty of folks out there who make such a diet work. In fact, over the years it's probably safe to say that most contest bodybuilders have gotten into shape on such a diet. Folks in the National Weight Control Registry (NWCR, which tracks successful dieters and their habits) reports most using some version of a high-carbohydrate diet. It'd be absurd to dismiss it out of hand even if that's what most people do.

At the same time, it's probably safe to say that the grand majority of folks don't do particularly well on such a diet, although it depends on a lot of interacting variables. The question is what differentiates the groups: why does such a diet work for some but not others? It's easy and convenient to say that the drug use among top bodybuilders makes such a diet workable but this is too pat of an answer. Nor does it explain the NWCR folks. In my opinion, the answer is more complex.

Now, upfront I will say that I think a 30/60/10 diet is a little unbalanced to begin with. My main problem is that the dietary fat is too low. The technical definition of a low-fat diet is anything less than 30% and the actual government recommended high-carb/low-fat diet is actually closer to 15% protein, 45-50% carbs and 30% fat or thereabouts.

As you might imagine, I find this lacking in protein for body recomposition or optimal athletic performance even if it's probably ok for the average person. Frankly, my ideal high-carb/low-fat diet would be in the realm of 25-30% protein, 50% carbs and 20-25% fat but I'll get to that in the proper chapter.

The first problem that typically crops up is that people take a diet that should be 'ok' (either 30/60/10 or 15/45-50/30) and screw it up completely. The problem is primarily one of interpretation. It's not uncommon to see dieters, especially women, turn a 30/60/10 diet into a 10/80/10 diet and they do it by overemphasizing high GI refined crap (the government and researchers thinks that folks are getting their carbs from unrefined grains but this is generally incorrect). Endurance athletes, who tend to overemphasize carbohydrates frequently, do the same thing: many, in my experience, are protein deficient (and studies are suggesting that very low fat intakes can hamper endurance performance). That takes a diet that was on the edge of being imbalanced to begin with and screws it up even further.

I can track a majority of high-carb diet failures directly to such a mistake in interpretation. And, if you take someone from 10/80/10 to anything else and the results will look like magic. It's not so much that the new approach is magical as the original approach was screwed up. Compared to something so unbalanced, anything will be better.

Ignoring this major problem, let's assume someone actually sets up a 30/60/10 diet more or less 'correctly' in terms of amounts. There can still be problems. The first is one of taste. A 10% fat diet is literally a non-fat diet and the small amounts of naturally occurring fats in non-fat foods tend to readily fill up the small fat allotment. Many people find such diets to be tasteless and bland which compromises adherence. Bodybuilders will just suck it up, of course; they are used to dieting with food that tastes like shit and a common statement is that 'When I diet, I just make sure I don't eat anything that tastes good.' Typical macho crap. But the rest of humanity is unlikely to stick to a diet that they don't find very tasty.

With such an extremely low fat intake, it can also cause problems with essential fatty acid intake which can be difficult to meet with so little of a fat intake. Even Dan Duchaine's high-carb/low-fat diet required 8% essential fats for a total of nearly 18% total fat content (this changed a 30/60/10 diet to 30/52/18 which is damn close to my ideal anyhow). As I mentioned in the chapter on fat requirements, a certain minimum is necessary for optimal fat-soluble vitamin absorption and 10% is approaching the point where problems can occur.

Another problem that crops up has to do with the types of carbohydrates being eaten. Researchers and other well-meaning types seem to assume that unrefined carbs are going to be the source of carbohydrates among the general public but this is generally not the case. Most of the athletes and bodybuilders who follow such a diet emphasize low GI, unrefined, high-fiber foods; in my experience, most of your typical dieters do not. It's one thing to eat 60% of your total calories from carbohydrates when all the foods you're eating have a GI that is extremely low.

As soon as you start making breads, pastas and other high GI foods a larger source of your total carbohydrates you run into a few problems. First is that the speed of digestion is very fast, a problem made worse by the low fat intake and generally low fiber intake of high GI food sources (and most people don't eat enough vegetables or fruit which would provide some much needed fiber). Along with that, the glycemic load (remember: GI * total carbs) goes up fast meaning blood glucose can be all over the map. For folks with even moderate insulin resistance (see below) this causes all kinds of problems.

Along with that, most of the higher GI carbs can be surprisingly high in calories. So while 2 oz of uncooked pasta may only contain 40 some odd grams of carbohydrates and 200 calories, an average large bowl of pasta may easily contain two or three times that. This can easily amount to hundreds of calories. Bodybuilders and athletes are typically obsessive compulsive to begin with, and measure all their food intake; your average dieter is not. So where an athlete will know exactly how many calories they are getting from the pasta or rice, the average person will end up eating too many calories.

That's ignoring all of the highly refined, high-carbohydrate low-fat foods that food companies brought to market (Snackwell's anyone?). As above, researchers seem to think that most people are increasing their carbohydrate intake from moderately refined sources but that's simply not the case in my experience. As soon as people heard that fat was bad and carbs were good, and food companies rushed high GI non-fat carb foods to market, folks went crazy. Studies even found that, subconsciously, folks figured they could eat more when it was low-fat. Any benefit from lowering the fat content was more than compensated for.

Basically, very high carbohydrate intakes tend to work best when the source of those carbs are low on the GI. If you're willing to eat almost nothing but low GI carbohydrates in the first place (let's set an arbitrary value of 50 or below), a high-carb diet will probably work. If not...

Related to this issue is meal frequency. Bodybuilders and athletes eating high-carb diets spread out the carbohydrates over 6 or more meals meaning their total carbohydrate intake per meal isn't actually that large. That, along with the low GI and high fiber intake minimizes problems with blood glucose swings and the resulting problems. Your average dieter, eating 3 large meals per day, with high GI carbohydrates and too little fiber will generally run into problems with such a high-carbohydrate intake.

Another related issue has to do with activity. Athletes who are burning a tremendous number of carbohydrate calories per day can tolerate/handle many more carbohydrates without problems than someone who is engaging in little to no activity (your average person). Refer to the chapters on carbohydrates if you've forgotten. A bodybuilder or endurance athlete doing 2 hour workouts on a nearly daily basis may be able to tolerate (and may in fact need) such high carbohydrate intakes; someone walking briskly 30 minutes per day three times per week does not.

Related to the activity issue is that of insulin sensitivity. Insulin sensitivity refers to how well (or how poorly) tissues respond to insulin. With high insulin sensitivity, small amounts of insulin generate a large response. With poor insulin sensitivity (insulin resistance), the body has to produce more insulin to get tissues to respond.

Individuals who are highly insulin sensitive handle high carbohydrate intakes to a better degree than folks with poor insulin sensitivity. I should mention, in this regards, that even folks with substandard insulin sensitivity can sometimes handle high-carbohydrate intakes when insulin sensitivity has been temporarily elevated (such as with glycogen depletion). This is relevant because certain dietary approaches (such as cyclical ketogenic diets) use this 'trick': they elevate insulin sensitivity temporarily and then load in lots of carbohydrates before insulin sensitivity goes back to substandard levels.

So what determines insulin sensitivity? Well, there are a lot of factors. First, there's a genetic component, activity affects it drastically (improving it), so does diet. Diets high in refined, high GI carbs tend to impair insulin sensitivity, so do diets high in saturated fats. Fish oils and unsaturated fats generally improve insulin sensitivity. A crucial determinant of insulin sensitivity is bodyfat percentage.

Obese individuals frequently become insulin resistant, which causes problems with carbohydrate intakes are excessive (moreso when they are high on the glycemic index). One of the main problems has to do with hunger and appetite. Under conditions of relative insulin resistance, a high carbohydrate intake (especially with very low fat intakes) tends to spike blood glucose levels, which spikes insulin, which crashes blood glucose. This tends to cause rebound hunger, making calorie control nearly impossible. It also makes people feel crappy with alternating periods of high and low energy. I've mentioned previously that studies are finding that high-carbohydrate/low-fat diets, especially when the carbs are high on the GI, cause detrimental effects on heart disease risk in insulin resistant individuals.

Additionally, some people seem to be carbohydrate 'addicts'. While it's debatable whether or not this is a true addiction, many people find that eating carbohydrates makes them want to eat more carbohydrates. Whether this effect is hormonal or just a taste effect is debatable but it is real. For such individuals, a high-carb/low-fat diet can cause problems in terms of calorie control. It's all good and well to tell such people to suck it up, or that dieting is supposed to be a test of willpower, but any diet that makes people feel lethargic and hungry all the time (from crashing blood glucose or simply the 'taste' of carbs) is not likely to be followed for very long.

As a final issue, empirically, high-carbohydrate diets can cause problems with stubborn fat mobilization. The mechanisms are discussed in a later chapter but folks with a lot of lower bodyfat can have problems getting extremely lean on high-carb diets unless they reduce the GI to very low levels. That means pretty much veggies and the few low GI starches. Women seem to crave carbohydrates more than men and sticking to such a diet can be a losing proposition.

Moderate carb/moderate fat

The next major dietary camp refers to any diet consisting of relatively moderate carbohydrate and dietary fat intakes. This includes diets such as Barry Sear's "The Zone", Dan Duchaine's "Isocaloric diet", 30/40/30 nutrition and others. Such diets generally recommend a macronutrient split based on fairly equal amounts of protein, carbs and fat. Various scientific rationales, usually involving hormonal control are typically given.

The Zone, for example, recommends a 30/40/30 split while Dan's Isocaloric diet is 33/33/33. Some bodybuilding gurus recommend 40% protein with 30% carbs and fats, for what it's worth. And, as I've mentioned before, cutting edge diabetic diets are in the realm of 15% protein (too low for athletes but protein can stimulate insulin release in diabetics), 40-45% carbs and up to 40% fat from monounsaturated sources. All of those approaches to fall within the description of moderate carbohydrate and moderate fat I gave last chapter.

Although I find a lot of the scientific rationales given for such diets to be pseudoscience at best, I do think that this type of moderate approach is probably close to ideal for most individuals. As I mentioned above, my ideal high-carb/low-fat diet is already close to 25-30% protein, 45-55% carbohydrate and 20-30% fat or so and moving from that to an Isocaloric or Zone diet is a rather minimal change to begin with.

But rather than focus on issues of eicosanoid balance or what have you, I simply think of such diets in terms of the fact that they tend to control blood glucose and hunger better because of the lowered carbs and higher fat content. It's a fairly simple trick, the increased dietary fat (and usually fiber) slows gastric emptying; the decreased carb intake decreases the overall glycemic load.

They also allow more food freedom and taste better than their near zero fat counterparts; this adds up to increased adherence. Frankly, if the various diet book authors had simply said "Hey, here's a diet that better controls blood glucose and insulin and blunts hunger by slowing gastric emptying" instead of making up physiology, I don't think there'd be as much criticism of such diets.

So what people might find such an approach to be ideal? As I described above, for that small percentage of individuals who are genetically very insulin sensitive, or who are burning a tremendous number of calories (from carbs) with daily or near daily workouts, higher carb intakes are probably more appropriate. At the very least, they can be tolerated. Since that describes a rather small percentage of people in the first place, I find the moderate carb/moderate fat approach more appropriate under most conditions.

For people burning fewer calories (or carbs) during the day, there's simply no real need for such high carbohydrate intakes. Folks doing more realistic levels of activity (perhaps an hour of weight training 3-4X/week and moderate cardio), carb requirements simply aren't that high. Look back at the chapter on carbohydrates if you've forgotten already.

From a caloric control issue, by lowering carbohydrates, and raising dietary fat, digestion is slowed and blood glucose levels tend to even out (note: the major effect is from reducing carbohydrates, fat is simply a caloric ballast). This generally means more stable energy levels and less pronounced hunger. This also allows foods higher on the GI to be chosen if desired (Dan allowed foods up to 70 to be consumed and this seems as reasonable a suggestion as any). Yes, it's almost always better to choose lower GI foods from a health standpoint but GI becomes far less critical when total carbohydrate intake is decreased. Remember that the glycemic load is the GI times the grams of digestible carbs: reduce digestible carb intake and GI becomes less important. Breads, pasta, rice and the rest can be consumed in controlled amounts on such a diet with far fewer problems.

Another potential benefit is that, by reducing carbohydrate intake, muscle glycogen is generally maintained at slightly lower. As I discussed in the chapters on nutrient metabolism, this enhances fat burning. At the same time, the moderate carb intakes should be sufficient to sustain performance in all but the most extensive types of training. As I discussed in the carbohydrate chapter, a typical 24 set weight workout may only burn 50 grams of carbs. A typical moderate carbohydrate diet should contain somewhere in the realm of 150-200 grams of carbs, more than sufficient to cover activity requirements and other minimal requirements (brain and the rest).

Moderate carb/moderate fat diets also tend to limit problems with insulin resistance related blood sugar crashes as a consequence of both reduced carbohydrate intake and increased dietary fat. However, some extremely insulin resistant individuals still run into problems with even moderate carbohydrate intakes. For such people, a more drastic decrease in carbohydrates may be necessary.

As well, those individuals who find that eating carbohydrates makes them want to eat more carbohydrate can also run into problems even with moderate carbohydrate intake. Women or men with stubborn fat deposits should generally find better mobilization by lowering carbohydrates; further reductions may be necessary in extreme cases.

I should mention, and I'll come back to this in a later chapter, that moderate carb/moderate fat diets tend to be more of a planning hassle than the other diets, especially at first. While I don't believe that you have to be exact in the percentages (as long as you get in the ballpark, you'll be fine), it can still be a pain in the butt to figure out meal plans.

From a simplicity standpoint, it's pretty easy to reduce fat and it's pretty easy to reduce carbs; getting moderate amounts of each can be a hassle. I'll give some shortcuts in the proper chapter. As well, with practice and time, it becomes relatively trivial to eyeball meals to get in the right ratio.


And finally we come to the low-carbohydrate or ketogenic diet, the diet with perhaps the greatest amount of controversy and argument surrounding it. Now, at the risk of beating a dead horse, and since I find many of my critics to be a little slow on the uptake, I'm going to go off on one last rant about this topic.

Rant mode on:

If you think of me as the keto-guru, you're probably expecting me to advocate the ketogenic/low-carb diet over all the others. People seem to think that since I wrote a book on the topic, I must be their strongest promoter. It makes me wonder if these morons actually read the book since I made it clear there that I didn't feel that ketogenic diets were necessarily ideal. I repeated this multiple times within that book.

I've actually found two different criticisms of my attitude towards ketogenic diets, depending on whether the critic is pro- or anti-ketogenic diets.

First is the group that feels that, since I didn't write negatively about keto diets, I must be their biggest advocate. Since they dislike ketogenic diets on some level, they feel that I should as well. Anyone who writes honestly and fairly about them is, by definition, in favor of them.

The second groups seems to feel that since I didn't say that ketogenic diets are magic, I must not believe in them. Since they think the diet is magic, they think I should too. Both groups, as usual, are guilty of projecting their own personal biases onto me. Both groups are apparently unable to count beyond two, since they see the world in a rather simplistic 'for/against' way.

To make things clear to both groups, I'm going to sum up my attitude towards ketogenic diets one more time. I'll be using simple words as much as possible.

My opinion on ketogenic diets is this: ketogenic diets are one of many (ok, three) dietary approaches available. They have advantages and disadvantages (like all diets). They are appropriate under some circumstances, relatively neutral under others, and entirely inappropriate under still other circumstances. They are not magic but they work tremendously well for some people and absolutely horribly for other. There are still questions regarding their long-term effects.

Of course, you could make the same statement about any dietary approach (reread the previous pages for a discussion of the other diets). They all have pros and cons, advantages and disadvantages. But since keto diets are among the most contentious, and since my name is essentially equated with the ketogenic diet, I'm having to make my stance that much more clear.

The point I've tried to make through this book, and one that I will continue to make (probably for the rest of my life since morons will always think of me as the keto-guru), is that, it's a matter of context, always. Whether a given diet, or training program, or supplement or drug is 'the best' always depends on context.

And if you continue to think that I only advocate or believe in ketogenic diets after reading that, I strongly suggest you go get your head checked for signs of trauma. At the very least get yourself sterilized; you're too stupid to be reproducing if you can't understand the point I'm trying to make here.

Rant mode off:

Now, I want to point out again, while a ketogenic diet is a low-carbohydrate diet, not all low-carbohydrate diets are ketogenic diets. Recall from the chapter on carbohydrates that an intake of carbs below 100 g/day is required to induce ketosis to any measurable degree (most ketogenic authors set an initial daily limit of 30 grams/day but I've never found a rationale for this recommendation). Not all low-carb diets reduce carbohydrates below the 100 g/day level so not all will induce ketosis. However, for the sake of typing and reading simplicity, I'm going to refer to all diets in this section as ketogenic.

For the purposes of this section, as mentioned last chapter I'm going to set carbs at 20% or less of total intake for a low-carbohydrate diet. Protein will be set at 30% and the remainder of the diet will be fat (in this example, 50%). As carbs go lower, fat intake goes higher, of course, up to the limit of 0% carbs and 70% fat. I should also mention that some authors prefer to do low-carbohydrate diets as nearly all protein affairs, with little to no dietary fat. While I personally see no real need for this (and fat tastes better), this can also work.

I should probably mention that ketogenic diets actually come in a few varieties. First are the standard or strict ketogenic diets where carbohydrates are kept reduced for extended (or unlimited) periods. Most of the mainstream low-carb/keto diets such as Atkins and Protein Power fall into this category.

Second are the modified ketogenic diets, which come in two flavors. The first is diets which reduce carbohydrates throughout the day but allow small amounts of carbs before, during, and/or after training. We named those targeted ketogenic diets (TKD) in my first book and I'll stick with that name. Finally are the cyclical ketogenic diets (CKD) such as Bodyopus, The Anabolic Diet, and Rob Faigan's NHE diet which alternates periods of ketogenic dieting with phases of high-carb intake. Since all of these diets revolve around a ketogenic/low-carbohydrate phase, I'll discuss them together.

Let's look at the SKDs first and when and where they might be appropriate. Frankly, I could probably just tell you that, if you don't meet the requirements for either of the previous two diets, some type of ketogenic diet is going to be appropriate for you; it's a choice by exclusion. To be safe, I'll include a little more commentary than that.

Obviously, folks who aren't doing much (or any) activity, ketogenic diets tend to be appropriate. Now, it's easy to simply say 'You should exercise and eat more carbs' but this isn't always possible. In cases of extreme obesity, or injury, or just plain laziness, exercise (especially intense exercise) may be out of the question. Since carbohydrate requirements are going to be extremely low (approaching the minimums discussed in the carbohydrate chapters), a ketogenic diet can be appropriate under those conditions.

Even individuals doing nothing but low-intensity activity (think walking and such), carbohydrate requirements are rarely very high. Low-carbohydrate diets are also appropriate under those conditions. There is some evidence that a low-carb diet might be useful for ultraendurance athletes (who typically perform for hours on end at fairly low intensities) but I'll discuss that below. I'll talk about higher intensity exercise performance in a second.

I've also found that folks with extreme insulin resistance do better in terms of energy levels and hunger/appetite control when they reduce carbohydrates. They go from constant energy swings to more stable energy. Research typically reports rather significant improvements in many health parameters such as blood cholesterol and triglyceride levels although this depends on total caloric intake and fat source as well. But for those individuals with severe insulin resistance and the resultant hyperinsulinemia (high-insulin levels), a near complete reduction of carbs may be necessary to bring glucose and insulin levels under control.

Along those lines, some people simply feel better on low-carbohydrate (especially ketogenic diets). They feel mentally more aware and function better, especially after a few weeks of adaptation. At the same time, as I've mentioned, some folks never seem to adapt to such diets, always feeling brain fuzzed, lethargic and all the rest. Many folks couldn't care either way. Is this genetics, a micronutrient imbalance, or individual variance? I have no idea, but I've seen it enough times to know it happens.

My general experience, in terms of giving you some guidelines to go on is this: if you feel fine, meaning that you function well with no major energy swings on a carb based diet, odds are you'll feel like shit on a ketogenic diet. You probably have good insulin sensitivity, high levels of activity, are fairly lean and are genetically well suited to run on carbohydrates.

If you're one of those individuals who always feel lagged out and unenergetic on high-carbohydrate diets (or get major energy crashes after a high-carb meal), you'll probably tend to feel wonderful on a low-carbohydrate diet. You may be inactive, carrying too much fat, or simply be genetically insulin resistant, meaning your body isn't set up to handle lots of carbohydrates.

This is where individual variance starts to play a role. I suspect that the differences in response have to do with many of the factors described in the previous sections: activity, insulin sensitivity and the rest. At the same time, research is finding that some people seem to be better adapted to using fat for fuel while others do not (meaning their bodies prefer carbohydrates). Genetics most certainly plays a role. Unfortunately, at present there's no easy way to know who will do best with higher fat and who won't. Use the guidelines above: if you feel good on high-carbs, you'll probably feel terrible on low-carbs and vice versa. Some people seem to have the metabolic flexibility to handle either approach at which point it's more an issue of preference and the other related issues.

While I feel that a moderate carbohydrate/moderate fat diet will probably be sufficient for all but the most extreme cases, there are always those individuals for whom a nearly complete reduction in carbohydrate intake may be necessary. And, as above, for those folks for whom even moderate amounts of carbs make them hungry for more carbohydrates (this tends to be far more true for starches than anything else), a complete removal of them may be necessary at least for the time being. I've found that, after time on a ketogenic diet, most people lose their taste for the high GI starches as their taste buds adapt. Frequently they can go back to a more moderate carb/moderate fat approach without getting into problems.

This is actually an important point, even for athletic individuals. Even with the most stalwart dietary discipline, athletes can have problems reducing calories on a diet because of the presence of what we might call 'diet-breaker' foods. That is, even in small amounts, certain foods make people cheat and overeat. While dietary fat can be problematic here, starches and sugars are typically what's craved on a diet.

Now, as anyone who read my rather torturous Bodyopus diaries so long ago knows, I am (well, used to be) one of those individuals. Even the smallest taste of starch made me want to eat more. Keeping bread or what have you in the house meant a diet that was destined to fail. Over time, I've found balance; I can (and usually do) use a moderate carb/moderate fat diet without running into too many problems.

As well, even athletic individuals can suffer from some degree of insulin resistance (at a genetic level) and may not handle carbohydrates well. In Bodyopus, Dan wrote that he felt most bodybuilding failures were do to poor insulin sensitivity. While that may be a bit of an overstatement, it definitely affects things.

For those individuals, even who are highly athletic, a complete removal of the diet breaker foods (or foods that interact negatively with poor insulin sensitivity) may be a necessary evil. As above, while I think moderate carb/moderate fat diets will probably do most of the work this isn't always the case. Some people will have to remove those foods entirely from their diet to be able to stick with it. As well as I've mentioned repeatedly above, for some people (women moreso than men), stubborn fat seems to come off better when carbs are restricted. I won't deal with the mechanisms here; just take it at face value.

So now we have a contradiction, even highly active individuals (meaning high carbohydrate requirements) may find a situation where carbohydrates need to be restricted to very low levels. The question then becomes of how to sustain exercise performance on such restricted carbohydrate intakes. Most critics of ketogenic diets would simply say 'Eat more carbs' but, as above, this may not be an option (also, as above, these people are idiots who can't see past a single dietary approach). So we have to compromise. Modified ketogenic diets are that compromise: they let folks use ketogenic diets while trying to maintain performance with the inclusion of carbs at specific times.

To date, two primary solutions have been developed, both of which I mentioned above. The first, and perhaps the simplest is the Targeted Ketogenic Diet (TKD). The TKD allows varying amounts (usually 25-50 grams) of high GI carbohydrates before, during or after training with carbohydrates being severely restricted the rest of the day. This accomplishes a few things. First, it allows dieters to eat some of the diet breaker foods, but under controlled circumstances. This helps deal with some of the psychological issues involved with dieting. Second, it goes a long way towards sustaining exercise performance by providing carbs around training. Third, since insulin resistance isn't much of a problem right around training, the high GI stuff that everybody likes to eat can be eaten fairly 'safely' (from a blood glucose/insulin release point of view). Even extremely insulin resistant/pre-diabetic individuals can usually eat carbs right after an intense workout without problems, as exercise elevates insulin sensitivity to high levels temporarily (there is also insulin independent glucose uptake during exercise so the body can utilize glucose without having to increase insulin levels).

The second solution, and the one I suspect most readers are aware of is the cyclical ketogenic diet (CKD). A CKD refers to any diet which alternates periods of low-carbohydrate (or ketogenic eating) with periods of high-carbohydrate eating. Diets such as DiPasquale's "Anabolic" and "Metabolic" diets, Dan's Bodyopus, and Faigan's NHE are all examples of CKD's. At the end of this book, I even offer my own take on the CKD, a redevelopment of the original Ultimate Diet that Duchaine and Zumpano introduced over 20 years ago.

CKD's are another compromise diet approach: they switch between a ketogenic/low-carbohydrate phase (for anywhere from 5 or more days) and a high-carb phase (lasting from 12 to 48 hours or more) to restore muscle glycogen and hopefully generate an anabolic response. They are for those athletic individuals who, for one reason or another, need to restrict carbohydrates severely, but sustain exercise performance.

Active individuals with severe (diagnosed) insulin resistance or even the beginning of Type II diabetes tend to fare poorly on CKDs; the extended carb-load period causes all of the problems that they are trying to avoid in the first place. The TKD is more appropriate for them.

On that note, I should mention a seemingly contradictory situation, that of endurance athletes. Interest in fat loading and fat adapting endurance athletes has been a long-term project for exercise physiologists and some research suggests that some endurance athletes can benefit from following a low-carbohydrate/high-fat diet for some period of time (5-21 days) and improve performance. This is especially true for ultra-endurance athletes who may perform for many hours at submaximal intensities, relying predominantly on fat for energy. A recent series of studies found that fat adapting cyclists for 5 days followed by a 1 day carb-load (similar to a CKD) improved performance in some athletes. The fat adaptation increased fat utilization at lower intensities but the carb-load made sure that sufficient glycogen was available for high intensity efforts. I'll discuss this in greater detail in the chapters on low-carbohydrate diets.

So summing up the section on low-carbohydrate diets. As above, we have two basic flavors of low-carb diet. The first is simply a diet in which carbohydrates are restricted for extended periods of time. Such diets are appropriate (and may be desired) for individuals who aren't doing much, if any, exercise (or are only doing low-intensity activity), who may have severe problems with insulin resistance, who have such an extreme carbohydrate 'addiction' that a full removal of starches may be required to control hunger.

The second flavor, the modified low-carbohydrate diets come in two separate groups. They are for those individuals who need (for some reason) to lower carbohydrates to low levels but still need to sustain exercise performance. First are the targeted type diets which have dieters restrict carbohydrates except around exercise (this is actually a very common approach to diet setup in bodybuilding literature). Second are the cyclical diets that alternate some period of low-carbohydrate dieting with periods of high-carbohydrate intake to refill muscle glycogen (and sometimes, it's argued, to stimulate a growth response).

Summing up

Ok, now you've hopefully got a better idea of which diet approach may be the most ideal for you. To make it a little more clear, I'm going to try to summarize all of the above information into a chart so you can see how the different variables interact.

DietActivityInsulin SensitivityCarb choicesCarb addictStubborn fat
HC/LFHighHighLow GINoNo
MC/MFMediumLow-ModerateMedium GIMaybeMaybe
  CyclicalHighLowN/AYes Yes

copyright © 2003. Lyle McDonald