People start diets for all sorts of reasons, but fundamentally, most folks who start controlling their food intake do so in order to lose weight. What most of them want to do, in fact, is lose fat weight; that is, reduce the amount of fat they carry on their bodies. You hear plenty of people express concern about being "overweight", but what they really ought to be concerned about is whether or not they are overfat, or carrying an excessive amount of bodyfat for their age, height, religious affiliation, etc.
What qualifies as an excessive amount of fat? That's for a doctor or nutritionist to decide, based on the above factors. For the record, only about 3% of total bodyweight in fat weight is considered essential fat for men; the figure is 9-12% for woman. It is important to note that although we wouldn't be able to live for very long if we dropped below this "essential fat" level, it is not by any means considered "healthy" to remove all but the "essential" fat.
Having said that, some dieters may not care if they lose fat weight, as long as they lose weight. Bully for them. For those of us who do want to lose fat weight in particular, any diet that looks only at total bodyweight lost is naturally inferior to a diet that looks at what sort of body weight is lost. The CKD is one of the latter, in that it attempts to maximize fat loss and minimize lean tissue loss, through a variety of techniques that we'll cover later. For now, let's look at the basic mechanism that allows us to lose fat weight at all: calorie restriction.
It's obvious enough to be almost self-evident. If you want to lose weight, you must create a caloric deficit. In other words, you must expend more energy than you take in. This can be accomplished by eating less food, exerting yourself more, or a combination of the two (the last generally being the most effective). For right now, let's look just at calorie restricting.
In order to eat hypocalorically, we must first have an idea of about how many calories we burn in the course of an average day. Now, there are all sorts of calculators out there for determining this number. Most of them are based on estimates, most of which are in turn based on statistical averages, some of which are based on other estimates. The bottom line is, none of the calculators will be very precise, so you might as well use something a little easier to remember: take your present bodyweight, in pounds, and multiply it by 14 or 15. That resulting number is your "maintenance calories" - the number of calories you have to take in, per day, to maintain your current bodyweight. Yes, this is a rough approximation, but it's not so rough as to be useless.
Once you've got your maintenance calories, multiply your bodyweight (again in pounds) by 11 or 12. This is a good caloric level at which to start your diet. Aim to take in about this many calories per day, and you'll begin to lose weight. How much weight? Consider that there are 3,500 calories in a pound of fat, and divide that number by your total daily caloric deficit. Take a hypothetical dieter who weighs 185 lbs. His mainetnance level is 2,590 (BW x 14), his dieting level is 2,035 (BW x 11) - so he'll be running a deficit of 555 calories per day if he eats 2,035 calories consistently. At this rate, it will take him 6.3 days to burn off the number of calories contained in a single pound of fat, or a little over a month (31.5 days) if he wants to loose 5 pounds of fat.
Of course, this is a highly contrived example. Someone who has created a 500-calorie-per-day deficit will probably not be making up that entire deficit with stored fat. There are also other factors to consider - the thermic effect of food, activity level on each day, etc. - but even ignoring those factors, these calculations can give you a rough outline of how your fat loss will proceed. They were never intended to do anything more.
Remember, also, that losing at a rate of 2 lbs / week or more is generally not a healthy or sustainable practice. The more gradually you lose the weight, the more likely it is that you will keep it off for the long term.
Of course, an important part of this is counting calories. Unless we're already dieting, most of us have only a general idea of how many calories we take in during a given day. Some people recommend that individuals just start counting the caloric content of everything that goes into their mouths, but I find this tedious. An easier way may be to sit down with a calorie chart or FitDay and figure out what a given combination of foods would gross calorically. Then, you have a rough idea of what you can eat in any given day and still hit your caloric target.
Fundamentals of the Ketogenic Diet
In practical terms, any diet that includes fewer than 100 grams of carbohydrates per day can be said to be ketogenic. To give you some background on how a ketogenic diet works: our bodies use glycogen as the primary source of fuel most of the time. Glycogen is the polymeric form of glucose, which we get from the carbohydrates in our diets. It can also be produced by gluconeogenesis, but that goes a bit beyond the scope of this article.
Our bodies store glycogen primarily in the liver and skeletal muscles.
If we eat plenty of carbohydrates, the body gets enough glycogen to use it almost exclusively for energy. Once we stop eating carbs and the glycogen is depleted, the body begins using other fuels, including free fatty acids (FFAs). This is fine for most of our bodily systems, but there are some organs in the body (the brain and central nervous system, for example) that cannot utilize FFAs. These organs can, however, use ketone bodies, which are produced to break down fat stores and use them for energy in a process called ketosis.
It should be noted that when we talk about ketogenic diets or "inducing ketosis", we are talking about ketosis-lipolysis, not ketosis-acidosis. Ketosis-acidosis is a potentially dangerous state that occurs primarily in diabetics (as DKA) as a result of reduced circulating insulin and a simultaneous increase in fatty acid oxidation, the combination of which acidifies the blood. Alcoholics who binge and fast are also at risk for another type of ketosis-acidosis related to ethanol metabolism.
For the average non-diabetic, non-fasting, non-binging Joe or Jane, ketosis-acidosis should not be a concern.
Ketosis-lipolysis, on the other hand, is the point of any ketogenic diet, because it results in a greater utilization of stored fat (the lipolysis part, which just means "fat burning").
Now that we have all that out of the way, let's get into the actual meat of the cycling ketogenic diet and what it does for you.
The Benefits of Ketogenic Diets
To my mind, there are two main benefits of ketogenic dieting. They are:
1) Easy(er) caloric restriction
2) Muscle maintenance
A greater degree of satiety usually results from diets higher in protein and fats. Because of this, a lot of folks find it easier to control calories on strictly ketogenic diets than on the typical American Snackwells / Healthy Choice diet that is extremely low in fat, but extremely high in "empty" carbohydrates. By "empty" carbohydrates, I refer to simple or refined foods that produce very little, if any, feelings of satiety.
For anyone who questions the validity of this, I invite you to buy one (1) box of Kellogs Smacks and twelve (12) cans of generic Chunk Light Tuna. Try eating the entire box of cereal in one sitting. The next day, try eating all twelve cans of tuna in one sitting. You may not be able to finish either, but I'm willing to bet you'll get significantly farther with the cereal. These two food choices have a nearly identical total calorie count, but grossly different macronutrient ratios.
This is not to say that simply eating protein and fat will make caloric restriction a snap. If your metabolism is geared to a higher caloric intake or you haven't dieted for a while (or ever), it will still be a challenge to eat a consistently hypocaloric diet. The ketogenic diet doesn't promise to make it easy, but a lot of individuals have reported that it does make things easier. This, given that the whole diet game is frequently anything but "easy", is saying something.
In my opinion, the second most important consideration in a diet (after maintaining hypocaloric intake) is getting adequate protein. I feel that the only type of ketogenic diet worth embarking on is one that provides adequate protein to the dieter. There are other ketogenic diets -- the Atkins diet, for example -- that can be ketogenic, while not providing adequate protein. To my mind, there is no point in a ketogenic diet that does not fulfill basic protein requirements, as it is almost guaranteed to be overfeeding fat -- which runs contrary to the goal of a diet.
Most sources agree that sedentary individuals should consume at least 0.8 grams of protein per kilogram of lean body mass daily. More active individuals, and especially those looking to increase muscle mass and strength, should consume in the range of 1.6 to 1.8 grams per kilogram. This is roughly equal to .8 - 1.0 grams per pound, so a lot of folks just round this to 1 gram of protein per pound of body weight, with good results.
My experience has been that if you set up a ketogenic diet with the express goal of achieving this recommended protein intake, controlling calories becomes easy. Start with your protein intake, add essential fatty acids, and finish off whatever calories are left with carbohydrates.
For those individuals who are specifically concerned with maintaining or building muscle mass and maintaining strength (athletes of all types, weightlifters/powerlifters, etc), dieting brings with it the attendant risk of lean body mass loss. In a hypocaloric situation, the energy has to come from somewhere, and in particularly lean individuals, odds are good that it will come from lean body mass as well as fat tissue. Getting adequate protein can, to some extent, minimize this catabolic effect.
In fact, studies have shown that a hypocaloric, high-protein diet - in other words, a ketogenic diet with adequate protein - is actually protein-sparing, above about 15% bodyfat.
What is a Cyclic Ketogenic Diet?
Just like it sounds, a Cycic/ing Ketogenic Diet is a ketogenic diet that cycles. In other words, this is not a diet you do day in, day out for X number of weeks, months or years: it is a diet that you break frequently. In fact, it is the only diet (that I'm aware of, at least) that you are supposed to break, and break often.
Anyone who has ever been in ketosis - for that matter, anyone who has ever tried low-carb eating for a few days - should be able to tell intuitively why the CKD exists. Being in ketosis is rarely enjoyable. For the first few weeks, there is an adaptation period during which most people report feeling run-down, depleted, "wasted", exhausted and / or tired. The slightest exertion (such as walking up a steep hill) causes muscles to burn. People feel irritable, out of sorts, and unable to make decisions.
If this was how you felt all the time in ketosis, it seems that few but the truly dedicated bodybuilders would do it. For most people these feelings disappear after the adaptation period, however, and are replaced with feelings of calm and more balanced, consistent energy. Not everyone is dedicated enough to wait long enough for the body to adjust, so the potential for burnout on a non-cyclic ketogenic diet (ie Atkins) can be high.
People crave carbohydrates during ketosis, for psychological as well as physiological reasons, and often what they most want are exactly the sort of high-glycemic, nutrient-devoid simple carbs that they were accustomed to eating before starting the diet. If you are maintaining a hypocaloric ketogenic diet, this temptation becomes even stronger, as the carb cravings are combined with the usual hunger pangs that accompany reduced calories.
A CKD offers a way to combat this. It offers a cyclical "refeed" (sometimes also called a carb-up). What happens during a refeed is that the dieting individual will change their diet to comprise mostly complex carbohydrates, limiting dietary fats as well as sucrose and fructose. Since the glycogen stores in their liver and muscles are depleted, these carbohydrates go straight to refilling them, instead of being added to the body's fat stores. For this reason, the amount of calories consumed during a refeed can be far above an individual's maintenance intake.
The goals of a refeed are threefold:
a) to refill depleted glycogen stores
b) to upregulate hormones and thyroid activity that is depressed during dieting
c) to provide a psychological "break" that makes the rest of the diet easier to bear
While both A and B are important physiologically, C is the linchpin of the CKD. If you know you'll be able to binge on bagels and milk in the near future, it makes adhering to your diet that much easier.
A refeed is also potentially dangerous, inasmuch as a careless individual can end up gaining fat, instead of merely achieving the three goals listed above. If you eat enough carbs to refill your glycogen stores and then some, you will get spillover into fat cells.
So, although a refeed is a much-needed respite after a long stretch of ketosis, the timing, duration and macronutrient composition of a refeed are crucial to the diet's overall success.
Guidelines for the Refeed
The frequency of a refeed will vary, based on a variety of factors unique to each individual. The general guideline is that the leaner you are, the more frequently you will need to refeed. This is for reasons related to hormone upregulation.
A crude schedule for refeeding frequency follows:
for % body fat..............refeed:
>10%......................every 5th day
10-15%...................every 7th day
15%+......................every 15th day
These numbers provide a rough starting point only, and are by no means definitive. Like many aspects of a diet, you should experiment and see what works for you.
And, for those of us who don't have any idea what our present bodyfat percentage is (and don't have a handy pair of calipers), here's another rough guideline for deciding when it's time to refeed. While you are eating hypocaloric, you will start getting hungry (this is especially true on a hypocaloric ketogenic diet, as you have carb cravings to deal with as well). Eventually, you will cross a line from just being "hungry" all the time to being ravenously hungry and almost unable to think about anything else. You may also start having vivid dreams about food and eating. When this happens, you can generally be safe in the assumption that it's time to start a refeed.
In general, a refeed should not be longer than 36 hours. For many folks, the most convenient refeed period is the weekend. A hypothetical CKD'er could be hypocaloric throughout the week, and then start her refeed on Saturday morning and finish it with lunch on Sunday. Of course, this can be fudged a bit, depending on how careful one is with their actual food intake. There is a rough relationship between caloric intake and duration in that someone who wants to refeed more, faster, should probably also refeed for a shorter total period of time in order to avoid fat spillover.
The bottom line is your refeed duration should be governed by your targeted caloric intake. Once you've hit your calorie target, you're done refeeding - so if you want to refeed longer, eat slower. We'll discuss guidelines for setting your refeed calorie target below.
As mentioned above, the primary component of a good refeed is complex, low-glycemic carbohydrates. Fructose and sucrose (and all simple sugars) should be limited as much as possible: ideally, fructose intake should be less than 50g and sucrose less than 100g. Dietary fat should also be kept low, typically under 50g.
So, a refeed means you can eat as much as you want? Not quite. There is a maximum upper limit in terms of calories that you shouldn't push past: it is about 16-18 grams of carbs per pound of bodyweight. So our hypothetical CKDer who weighs 185 lbs would theoretically be safe eating 2,960 grams of complex carbs on his refeed day. If he also takes in some dietary fats or protein, that number would come down to allow for those other nutrients. Remember: fat is 9 calories to the gram, carbs and protein are both 4.
The Hidden Recommendation: Weight Training
Okay, I'll come clean. As an amateur bodybuilder and boxer, I've had experience with CKD, non-cyclic ketogenic diets, and non-ketogenic hypocaloric diets, both in and out of weight and boxing training.
And, from all my experiences, I can say that I believe that the effectiveness of a CKD will be maximized by weight training. I feel it is a necessity if one wants to minimize lean tissue loss. If you already weight train, great; try implementing a CKD and watch your results.
If you don't train and want to get started, well, that's another issue that goes beyond the scope of this article, but I'd advise you to check out the myriad online resources to get some ideas on how to proceed.
The Vegetable Question
"But," I hear you say, "Less than 100g of carbs per day doesn't give me much room for fruits or vegetables.....both of which are essential, as everyone knows, for a healthy and well-balanced diet."
This is true. I won't debate that fruits and vegetables are good for you (vegetables in particular), and I'm not asking you to cut them out of your diet. I would recommend, in fact, that if you are eating 50-100g of carbs per day, you get the majority of them from vegetables, particularly dark, leafy vegetables high in fiber. Sure, a few slices of bread at 35g / slice are tempting, but you will get more raw nutrients from the veggies.
What about kidney damage, then? What about cancer, cholesterol and cardiac arrest?
Well, what about them? If you're worried about what a ketogenic diet might do to your long-term health, remember that nobody says you have to stay on a CKD for the rest of your life. If you are currently overweight and need to drop a considerable amount of weight, give it a try and see if you like the results. If it works for you, use it to get down to your target weight and bodyfat % level, then implement a more long-term, balanced diet and exercise plan to maintain those levels. The diet that is going to work in the long term is the one that you can adhere to in the long term. Remember: moderation in all things, including moderation.
The Final Word...Finally
A CKD is not for everyone, nor it is a "magic" diet that will guarantee you good results. At best, it is a way to assist you in your fat loss goals by improving satiety and thereby aiding restricted calories, improve adherence by providing frequent breaks, and targeting bodyweight loss to adipose tissue by virtue of increased protein consumption. Many people have gotten good results from a CKD, but that is no guarantee that you will.
Regardless, the most important thing you can do for your health is to be informed. Follow the links in this article and below, hit the newsgroups, do some independent research at your local library. If you don't like the idea of a CKD for any reason, come up with your own diet plan and give it a try. If it doesn't work, change it until it does. This is all you really have to do to achieve your health goals.
DISCLAIMER: I take no responsibility for any health damage you may suffer on this or any other diet. Consult with a qualified, informed doctor or nutritionist -- in other words, someone who knows what they're talking about, not someone who has just memorized the USDA food pyramid -- before making any major dietary changes.
The Easy Gourmet's Nutrition Information
The Glycemic Institute
Rick Mendosa, Diabetes Consultant
The Ketogenic Diet - Lyle McDonald
Weights by Mistress Krista