![\"\"](\"http:\/\/www.proteinpower.com\/drmike\/wp-content\/uploads\/2010\/02\/Educational-software.jpg\")
I\u0092ve got to apologize in advance for the length of this post, but in order to thoroughly do what needs to be done, it took the space.<\/p>\nI\u0092ve got to apologize in advance for the length of this post, but in order to thoroughly do what needs to be done, it took the space.<\/p>\n
Readers of this blog who have been around for a couple of years have been through the Anthony Colpo (AC) fiasco with me.\u00a0 For those of you who weren\u0092t around at the time, I\u0092ll give a brief – a very brief – overview of what happened so you\u0092ll understand what this is all about.<\/p>\n
I wrote a post in September 2007<\/a> describing two different diets and their outcomes.\u00a0 The first was designed by Ancel Keys and was a 1500+ calorie low-fat, high-carb diet; the other, designed by John Yudkin, was a 1500+ calorie low-carb, high-fat diet.\u00a0 The subjects following the two diets experienced drastically different results.<\/p>\n This post, for whatever reason, inspired AC, a trainer and self-taught nutritional guru from Australia, to go into mad-dog attack mode.\u00a0 I wasn\u0092t the first person he had gone after, but I became the first to fight back<\/a>.<\/p>\n Around the same time AC took it upon himself to attack me, he had just published an online book on weight loss that he was beginning to promote called The Fat-Loss Bible<\/em>.\u00a0 A more cynical person than I might have thought AC picked this fight in an effort to get some free publicity for himself and his book.\u00a0 If that was indeed his motivation, he may have gotten a little more publicity than he had bargained for.<\/p>\n I took a look at his book – which I hadn\u0092t realized even existed prior to this kerfuffle – and found it to be much like the ad for the educational software pictured above to the left.\u00a0 At first glance, it looked reasonable, but upon closer inspection, it had some problems.<\/p>\n I made the offer to readers to dissect AC\u0092s book if that\u0092s what they wanted.\u00a0 Or I could ignore the whole thing and continue with my regular posting.\u00a0 A majority in the comments section voted for me to dissect.\u00a0 I dug into the book, pulled all the papers cited, but subsequently got involved in other stuff and forgot about AC and his book.\u00a0 He more or less dropped from sight, but has surfaced lately.\u00a0 I had forgotten all about him, his book and the whole situation, but his new antics have stirred a few readers to ask about the dissection that I promised but never came through with.<\/p>\n So, with that preamble, here it is.<\/p>\n The crux of AC’s objection to me (and a few other people, namely Gary Taubes, Richard Feinman and Gene Fine) is that I (and they) believe there is a metabolic advantage that becomes manifest during low-carb dieting.\u00a0 AC has taken the position that my idea of the low-carb driven metabolic advantage means that people following low-carb diets can eat all the calories they want and lose massive amounts of weight as long as they keep their carbs reduced.\u00a0 He accuses me of leading people astray by encouraging them to eat, eat, eat as long as carbs stay low.<\/p>\n I don\u0092t know where he got this idea because I have certainly never said such a thing anywhere.\u00a0 The metabolic advantage brought about by low-carb dieting is probably somewhere in the neighborhood of a 100-300 calories, which isn\u0092t all that much.\u00a0 This few hundred calories don\u0092t even come into play until the 1500-2000 calorie range of consumption.\u00a0 I\u0092ve written about this numerous times and have always used these figures, so, as I say, I don\u0092t know where the idea that I believe the metabolic advantage allows low-carb dieters to eat huge numbers of calories and still lose weight.<\/p>\n I don\u0092t plan to go through The Fat-Loss Bible<\/em> in its entirety or this post would take on the dimensions of War and Peace<\/em>.\u00a0 I\u0092m going to limit my comments to Chapter 1, titled “Myth 1: Don\u0092t Count Calories.”\u00a0 This first chapter is the one that tells why AC so fervently believes there is no metabolic advantage.<\/p>\n AC sells his book online, but (at least the last time I checked) it can be downloaded only on a PC.\u00a0 At the time this dispute started I had a PC, which I used to download the book.\u00a0 Since then, my PC has given up its ghost and I now use Macs exclusively.\u00a0 So, the copy I have is about two years old.\u00a0 I don\u0092t know if AC has changed it since; consequently, I don\u0092t know if my critique applies to the book as it exists today.\u00a0 AC changes his book all the time, updating here and there, and I don\u0092t blame him for it.\u00a0 I do it with this blog all the time.\u00a0 I find typos in old posts and sentences that I don\u0092t like.\u00a0 I change these things all the time and the blog is the better for it, so I don\u0092t blame him if he does the same thing.\u00a0 But I just want everyone to know that I\u0092m critiquing the book as it was when he launched his attack.<\/p>\n AC firmly believes that a calorie is a calorie is a calorie.\u00a0 He believes that people lose the same amount of weight dieting irrespective of the composition of whatever diet they\u0092re on.\u00a0 He believes that a given person will lose exactly the same amount of weight on, say, a 1600 calorie diet whether that diet is a low-carb diet or a low-fat diet or any other kind of diet.\u00a0 It is the calories that set the weight loss, not the macronutrient composition or any other factor.<\/p>\n I don\u0092t know if AC came to this conclusion then went looking for studies to confirm his bias or if he came to this conclusion because of the studies he read.\u00a0 The first chapter of his book contains a number of studies he trots out to \u0091prove\u0092 his idea that only calories count.<\/p>\n There have been many out patient studies that have shown a metabolic advantage and many that haven\u0092t.\u00a0 Overall a greater number of studies demonstrating a metabolic advantage exist than studies showing no such metabolic advantage.\u00a0 The first part of the first chapter of The Fat-Loss Bible<\/em> goes into great detail describing why such studies are worthless.\u00a0 He makes a fairly plausible argument as to why people on low-carb diets might tend to overreport consumption while those on low-fat diets may underreport.\u00a0 If correct, this difference in reporting would create the appearance of a metabolic advantage where none exists.<\/p>\n To solve this problem, AC turns to what he calls<\/p>\n strict \u0091metabolic ward\u0092 studies in which, for the entire duration of the study, the participants are confined to a research facility where they can only eat the foods supplied by the researchers.<\/p>\n<\/blockquote>\n On the surface this seems to make sense.\u00a0 Put the subjects under lock and key, give them just the food you want them to eat, and see what happens.\u00a0 You\u0092re going to have some individual variation, but if evaluate enough subjects and they all end up losing the same amount of weight irrespective of macronutrient composition, then you\u0092ve got some pretty good evidence that there probably isn\u0092t a metabolic advantage.<\/p>\n But as obvious as this appears at first glance, there are problems with this approach.<\/p>\n The first problem is a problem of measurement.\u00a0 Newton derived his gravitational laws and everything scientists measured obeyed them.\u00a0 These laws became sacrosanct.\u00a0 If some observation didn\u0092t conform to Newton\u0092s laws, then the observation was faulty because Newton\u0092s laws were infallible.\u00a0 Those quirky movements of planets way out on the edge of the solar system were off a little from Newton\u0092s predictions, but, hey, it\u0092s got to be a measurement error somehow.\u00a0 Then Einstein came along with his theory of relativity, and all the weird deviations conformed to Einstein\u0092s laws.\u00a0 Newton had been superseded.\u00a0 Because the caloric differences brought about by a metabolic advantage (at least as I see it) are so small, weighing subjects in pounds and kilograms may miss it.<\/p>\n That\u0092s the first problem.\u00a0 But there is a problem much greater than that.\u00a0 One that AC isn\u0092t aware of because he doesn\u0092t really have any real-world experience in doing nutritional studies in a hospital.<\/p>\n When subjects are studied in \u0091metabolic wards\u0092 they aren\u0092t locked away and under constant observation.\u00a0 In fact, often enough, they aren\u0092t even in a hospital at all.\u00a0 A \u0091metabolic ward\u0092 is simply a part of the hospital set aside to do nutritional studies.\u00a0 And often it isn\u0092t even a specific part of the hospital.\u00a0 Subjects can be scattered about among the other patients.\u00a0 Subjects can have visitors, can roam through the hospital, can even go to the cafeteria.\u00a0 A \u0091metabolic ward\u0092 study can mean anything from: careful observation; to check into the hospital for a couple of days; to get trained on the diet then follow it at home; to check in, go to work all day, then come stay in the hospital all night. They are definitely not the strictly-controlled studies AC thinks they are.\u00a0 He confuses them with \u0091metabolic chamber\u0092 studies, which are a horse of a different color.<\/p>\n The opportunities to cheat in a \u0091metabolic ward\u0092 study are, for the most part, as great as the opportunities to cheat in an outpatient study, especially since many of the subjects are outpatients most of the time.\u00a0 There is a difference though.\u00a0 When people are on outpatient studies they are more likely to at least admit their cheating and record what they cheat with than they are in \u0091metabolic ward\u0092 studies.\u00a0 Some of the studies AC sites are formula diet studies in which shakes made of specific caloric and macronutrient composition are provided to subjects throughout the day.\u00a0 (Or are given to them to consume outside the hospital at work or wherever.)\u00a0 These are the kinds of programs you wouldn\u0092t want to report cheating on.\u00a0 And these subjects do without question cheat.\u00a0 The fact that the data is reported as coming from a \u0091metabolic ward\u0092 study gives it a veneer of accuracy that it doesn\u0092t really deserve.<\/p>\n AC gathered up a bunch of these \u0091metabolic ward\u0092 studies – 17 to be exact – that he uses to prove his point that there is no metabolic advantage and that only calories count.\u00a0 He lists these studies in a chart (reproduced below), then proceeds to go through them one at a time.<\/p>\n On the ones that confirm his bias, he spends little time.\u00a0 Just a brief description typical of this one describing the first study.<\/p>\n In a paper aptly titled \u0094Calories Do Count\u0094, Kinsell and co-workers admitted five obese subjects to a hospital metabolic ward, then fed them liquid formula diets.\u00a0 The diets ranged in protein content from 14 to 36 percent, fat from 12 to 83 percent, and carbohydrate from 3 to 64 percent.\u00a0 The calorie content of the various diets was held constant for each patient irrespective of diet composition.\u00a0 As they switched from one diet to another, each patient continued to lose weight at a similar pace.\u00a0 Concluded the researchers: \u0093…it appears obvious that under conditions of precise consistency of caloric intake, and essentially constant physical activity, qualitative modification of the diet with respect to the amount or kind of fat, amount of carbohydrate, and amount of protein, makes little difference in the rate of weight loss<\/em>. [Italics in the original]<\/p>\n<\/blockquote>\n This is a great study to start with because it contains many, many flaws that AC is blinded to by his own confirmation bias.\u00a0 It\u0092s a terrible study.\u00a0 Let me show you why.<\/p>\n Here is the first paragraph of the study.\u00a0 And I\u0092m not kidding.\u00a0 This is directly quoted from the paper.<\/p>\n The accumulation of excess adipose tissue is a malady which affects many people.\u00a0 That undue preoccupation with the pleasures of the table contributes to the disease has geen [sic] generally accepted in most quarters; or, to express the matter differently, majority opinion has held that the first law of thermodynamics applies to the human machine quite as predictably as it does to inanimate machines.\u00a0 Despite this body of \u0093official opinion\u0094 one finds many obese individuals who are either convinced that their food intake completely fails to explain their adiposity, or who spend time and money in the search for the magic potion or pill which will enable them to consume food in any quantity but still maintain or achieve a slim figure.<\/p>\n<\/blockquote>\n Do you think there might be just a little bias in this author and his co-workers?\u00a0 From this first paragraph one sees by the reference to the first law of thermodynamics the set of the sail of these researchers.\u00a0 Plus it\u0092s pretty clear that these researchers don\u0092t like overweight people and think obesity comes from a \u0093preoccupation with the pleasures of the table…\u0094\u00a0 How do you suppose their data is going to turn out?<\/p>\n First of all, were these five subjects inpatients in a metabolic ward or did they just pick up their formula and take it home.\u00a0 Did the live in the hospital or just spend the night?\u00a0 No information is given. His weight on admission to the metabolic ward was 270 pounds.<\/p>\n<\/blockquote>\n Was he admitted to the ward where he stayed full time for the full 70 days of the study?\u00a0 I doubt it, and I\u0092ll describe why in a bit.\u00a0 Or was he admitted for his initial workup then released to continue his diet at home.\u00a0 I suspect the latter.\u00a0 Whatever the situation, this is all the study says about it.<\/p>\n Here are the descriptions of how the rest of the subjects entered the study:<\/p>\n Second subject:<\/p>\n Weight on admission to the study was 227 1\/2\u00a0 pounds…<\/p>\n<\/blockquote>\n Third subject:<\/p>\n At the time the study was undertaken her weight was 199 pounds…<\/p>\n<\/blockquote>\n Forth subject:<\/p>\n At the time the study was undertaken, her weight was 211 1\/2 pounds…<\/p>\n<\/blockquote>\n Fifth subject:<\/p>\n Patient GTAY was a 61 year old white female with a history of diabetes for more than 20 years.\u00a0 She had received insulin in the past but could be maintained in a satisfactory diabetic control with diet and tolbutamide.\u00a0 Milky fasting plasma was discovered in July 1962.\u00a0 Other findings included evidence for coronary and peripheral atherosclerosis, and diabetic retinopathy.\u00a0 She had partial removal of a goiter 40 years ago, but was essentially euthyroid during her stay in the metabolic ward.<\/p>\n The study in this patient was actually directed toward evaluation of her hyperlipidemia, but she is included in this report since she was maintained on quantitatively constant, eucaloric regimens containing high fat and high carbohydrate respectively, and also received both saturated and unsaturated fat.<\/p>\n<\/blockquote>\n This last patient wasn\u0092t even accepted into the study as a subject for a diet study but more or less added after the fact.<\/p>\n There were five subjects in this study that lasted for anywhere from 65 to 77 days.\u00a0 We can\u0092t really tell which subjects went how long. Nor can we really tell if it was an inpatient study or just one where the subjects checked in.\u00a0 Nor do we know how much weight each lost over how long a period.\u00a0 We know the starting weights and that\u0092s about it.<\/p>\n The data as displayed looks like data collected in an inpatient study, but the paper itself only implies that it is.\u00a0 As you might imagine, inpatient studies are tremendously expensive, and, consequently, authors tend to make sure readers of the study know they are inpatient studies.\u00a0 In this paper, we have to guess.<\/p>\n If these are truly inpatient studies for 65 to 77 days, we need to address another point: the quality of the subjects in such studies.\u00a0 Who do you know who would have the time or inclination to spend two to two and a half months in a hospital full time?\u00a0 People who are willing to spend the time in such facilities are usually not the most reliable. They are typically unemployed with little education and, for the most part, are imbued with a lack of understanding as to how important their rigid adherence to the protocol truly is.\u00a0 I will be the first to say that not everyone who has ever volunteered for such a study falls into this category, but, unfortunately, many do. I\u0092ll let a couple of the authors of these metabolic ward studies expound on this fact a little later.<\/p>\n The age range of these subjects is from 25 to 61. All of the subjects in this trial save one have serious medical problems and are under treatment with multiple drugs.\u00a0 The one who doesn\u0092t have serious problems is a 25 year-old male who has \u0093been grossly obese since childhood.\u0094\u00a0 These are not the subjects you would want in a study of this nature.<\/p>\n The subjects getting the most calories got 1200 per day while those getting the least consumed 800 calories per day.\u00a0 As I\u0092ve written before, if calories are kept ultra low, all the calories – irrespective of composition – are going to be used for energy.\u00a0 And under those circumstances, you would expect there to be no metabolic advantage.\u00a0 And you would expect weight loss to pretty much follow a trajectory driven solely by caloric deficit, which is pretty much what happens in this study.\u00a0 But it\u0092s difficult to tell because of how terrible this study is presented.\u00a0 There is a starting weight, but no ending weight for the subjects.\u00a0 And, although the Methods section reports that the study lasted from 65 to 77 days, my calculations based on the data provided shows the study lasted from 64 to 82 days.\u00a0 Which are we to believe?\u00a0 Without an ending weight for the subjects and a precise number of days under caloric restriction, how do we really know how much they lost verses how much they should have lost given the number of calories they were getting?<\/p>\n And we have this other little tidbit thrown in when discussing the results of one patient, RTEA, who was a 26 year old female with \u0093a history of resection of a cystic chromophobe adenoma of the pituitary…followed by radiation\u0094:<\/p>\n Rate of weight loss was greater during the last 2 weeks on the high fat, high protein intake than during either of the other 2 dietary periods.\u00a0 This probably does not have significance on view of the \u0093stair case pattern\u0094 of weight loss.<\/p>\n<\/blockquote>\n Say what?\u00a0 So they do have a subject that shows greater weight loss (and late in the program rather than early), yet they toss off the data with a bunch of weasel words implying that it probably isn\u0092t significant.<\/p>\n I suggest you pull down the full text of this study at the bottom of this post so you can see for yourself how terrible it is.<\/p>\n I\u0092m certainly not going to go through all 17 of the studies in this fashion because this post would then truly gargantic, but I wanted to go into this one at length to show that so-called \u0091metabolic ward\u0092 studies, those AC terms the \u0091gold standard\u0092 of medical research can be very, very flawed.\u00a0 I, for one, would not want to be making any categorical statements based on the data contained in this study we just evaluated, that\u0092s for sure.\u00a0 If AC weren\u0092t so blinded by his own confirmation bias, he would have laughed this study off.\u00a0 If I had used it to ‘prove’ a metabolic advantage – based on the one patient described above who had more weight loss on the high-fat diet – he would have had a field day.<\/p>\n Next, let\u0092s turn our attention to the Liebel et al study.\u00a0 It\u0092s number 11 down the chart if you\u0092re counting.\u00a0 Here\u0092s what AC says about it:<\/p>\n Leibel and co-workers took 13 subjects, determined how many daily calories each needed to maintain his\/her weight, then proceeded to feed them, in crossover fashion, diets differing in their macronutrient content.\u00a0 Despite wide variations in protein, fat, and carbohydrate intake, the subjects maintained their weight irrespective of diet type.\u00a0 This included two subjects who followed low- and high-carb diets (15 percent and 75 percent carbohydrate, respectively) for a minimum of 34 days each.<\/p>\n<\/blockquote>\n That\u0092s it.\u00a0 That\u0092s AC\u0092s commentary on the study.\u00a0 I suppose readers are meant to believe that this study showed that it was all a matter of calories with no difference in terms of weight lost versus macronutrient composition of the diet.<\/p>\n The Leibel et al paper is a great one because it shows just how sloppy AC is in his presentation of data and, no doubt, in his own evaluation of the medical literature.<\/p>\n Go back and reread AC\u0092s description of how the study was done.\u00a0 Looks like Leibel et al did a hands-on study of these subjects, right.\u00a0 Well, that\u0092s not exactly how it worked.\u00a0 Here is what really happened as reported by Leibel et al:<\/p>\n The records of all subjects studied by the Lipid Laboratory of the Rockefeller University Hospital between 1955 and 1965 who were fed lipid-formula diets of various carbohydrate (CHO) and fat composition were reviewed.<\/p>\n<\/blockquote>\n Leibel et al didn\u0092t do squat in terms of studying subjects.\u00a0 They went back through 40-year old records of subjects who had undergone formula feeding in the 1950s and 1960s to drag out records of 13 subjects (they actually drug out 16, but three were of children) who met their experimental parameters.\u00a0 They weren\u0092t looking for evidence of a metabolic advantage; they were looking to see if fat intake irrespective of calories made people gain weight.<\/p>\n Out of the countless studies done in those early years, they wanted to see if any could show that fat intake increased weight gain to a greater extent than the calories consumed as fat.\u00a0 As they put it in the Introduction to their paper:<\/p>\n One group of investigators concluded that \u0093fat intake may play a role in obesity that is independent of energy intake.\u0094<\/p>\n<\/blockquote>\n The Leibel et al paper was published in 1992, the time in which the low-fat mantra was at its zenith.\u00a0 It was a time that many people who should have known better were telling us we could eat all we wanted as long as we limited fat.\u00a0 Fat makes us fat, we were told.\u00a0 Cut it and you lose.\u00a0 What Leibel et al were trying to show in this paper was that the weight gain or loss effects of fat were a function of the calories contained in the fat, not some other magical property that makes people gain weight above and beyond calories.<\/p>\n Before we get to the interesting data in this study, let\u0092s take a look at what the guy who actually did this work had to say.\u00a0 Leibel\u0092s group went through old formula feeding studies done by Edward H. Ahrens, M.D., the head of the formula feeding lab at the time and the lead author of all the old papers referenced by Leibel.\u00a0 Says Dr. Ahrens about the subjects in the inpatient studies:<\/p>\n Thirty-eight of forty patients were observed continuously under strict metabolic ward conditions; four of the forty [I know, the math doesn\u0092t add up] were sufficiently motivated and intelligent to follow the regimen at home. (Ahrens EH et al 1957<\/a>)<\/p>\n<\/blockquote>\n A couple of points here.\u00a0 First, if four subjects out of 40 were \u0093sufficiently motivated and intelligent\u0094 to be sent home with formula and instructions, what does that say about the other 36 (or 38)?\u00a0 Which is to my point earlier about the quality of subjects recruited into metabolic ward studies.\u00a0 Second, were some of the patients whose data was used for the Leibel paper those who were sent home?\u00a0 If so, it blows AC\u0092s notion of being unable to rely on any data gathered from free-living subjects.<\/p>\n Dr. Ahrens in another paper describing his 15 years of experience using formula diets says this about cheating in metabolic ward studies:<\/p>\n Such cheating is a natural (but dismaying) consequence when a patient\u0092s dissatisfactions with any part of the ward routine are not quickly enough appreciated by the ward personnel.\u00a0 Anticipation of the discontent is the clinician\u0092s daily concern.\u00a0 The closer the relationship between the patient and his medical attendants, the less likely cheating is to occur.\u00a0 We have detected<\/em> [my italics] cheating in only eight patients; undoubtedly others have gone undetected, but we feel the problem has been surprisingly minor. (Ahrens, EH 1970<\/a>)<\/p>\n<\/blockquote>\n These are the subjects under lock and key.\u00a0 The people running the study have to maintain constant vigilance to prevent cheating.\u00a0 How about those who only check into the metabolic ward to sleep and spend the rest of their days at work or home?\u00a0 And those are the subjects who make up most of the metabolic studies you read about.<\/p>\n One last interesting point about the Leibel paper.\u00a0 The subjects they looked up in their retrospective analysis had undergone experiments during which they were given formula in amounts sufficient to maintain their weight.\u00a0 As they lost or gained weight, their caloric intake was increased or decreased to compensate so that their weight stayed about the same.\u00a0 According to the old papers about the original studies, the researchers tried to keep the subjects from fluctuations greater than one kg.\u00a0 One kg equals two pounds.\u00a0 If there was a metabolic advantage, it would probably show up within this two pound range and would be considered insignificant in terms of how this study was presented.<\/p>\n Some of the subjects, however, did lose or gain weight. Leibel et al then adjusted their caloric intake on paper to compensate for the weight differential.\u00a0 In other words, if a patient lost weight on a given number of calories of a precise formula in the original study, Leibel et al would adjust the intake (40 years after the fact) to compensate for the weight loss.<\/p>\n One subject, a 55-year-old male with a BMI of 32, maintained his weight on a high-carb formula at 2871 calories per day.\u00a0 The same subject then required 3501 calories to maintain his weight on a 70% fat, 15% carbohydrate diet.\u00a0 Sounds like a metabolic advantage to me.<\/p>\n There were two papers in AC\u0092s list of 17 that did show what could be considered a metabolic advantage.\u00a0 In other words, subjects on the low-carb diet lost greater amounts of weight than subjects on low-fat, high-carb diets of the same number of calories.\u00a0 These are two of the three studies by Rabast et al that are the 4th and 6th studies on the list of 17 shown above.<\/p>\n How did AC deal with this seeming refutation of his notion that no metabolic advantage exists?\u00a0 By typical AC flimflammery.<\/p>\n In their 1981 study, Rabast et al observed significantly greater potassium excretion on the low-carbohydrate diets during weeks one and two.\u00a0 A considerable amount of potassium inside our bodies is bound up with glycogen, so the greater potassium losses in Rabast\u0092s low-carbohydrate dieters may indeed be a reflection of greater glycogen, and hence water losses.\u00a0 Until recently, potassium excretion was often used a a marker or lean tissue loss; in Rabast\u0092s study, this would indicate that the low-carbohydrate diet subjects lost more lean tissue.\u00a0 As lean tissue holds a considerable amount of glycogen, this would again point to glycogen-related water loss as the explanation for the allegedly \u0093significant\u0094 differences in weight loss. [Italics in the original] If the low-carbohydrate groups maintained greater lean tissue and\/or glycogen losses at the end of the study, then this would easily explain their greater weight loss.<\/p>\n<\/blockquote>\n Regardless of whether Rabast et al\u0092s findings were the result of water loss from glycogen depletion, pure chance, or some other unidentified factor, they should be regarded for what they are: An anomaly that has never been replicated by any other group of researchers.\u00a0 For a research finding to be considered valid, it must be consistently reproducible when tested by other researchers.\u00a0 As proof of the alleged weight-loss advantage of low-carbohydrate diets, the findings by Rabast and colleagues fail dismally on this key requirement.<\/p>\n<\/blockquote>\n Wow!\u00a0 Where do we start?<\/p>\n First, AC didn\u0092t mention Rabast\u0092s 1979 study in which 117 patients were admitted to the hospital and studied on formula diets.\u00a0 I assume these subjects were hospitalized round the clock because in the body of the paper it states:<\/p>\n …and as the patients were under constant supervision differences in food intake between the two groups could be excluded.<\/p>\n<\/blockquote>\n Unlike the Kinsell study (the first of AC\u0092s 17 I described in detail above), the authors of this study were expecting a different outcome.\u00a0 As discussed, Kinsell was obviously biased going in against the notion of anything other than calories count.\u00a0 Rabast et al went in biased against low-carb diets:<\/p>\n The popularity of so-called \u0091fad\u0092 diets, low in carbohydrates and relatively high in fat, has continued to spread, especially among lay groups.\u00a0 The caloric intake is only slightly limited, if al all; alcohol is allowed most of the time, and fat is consumed in the form of saturated fatty acids.\u00a0 However, this kind of dieting, which must always be carried out on a long-term basis, has proved harmful.\u00a0 The cholesterol intake can lead to severe health damage and clearly contributes to atherosclerosis.<\/p>\n<\/blockquote>\n After keeping the 117 subjects on low-carb vs high-carb diets of the same number of calories for 25 – 50 days, and probably hoping to find that those on the low-carb diet didn’t lose any more weight than those on the low-fat diet, the subjects on the low-carb formula diet lost considerably more weight than those on the low-fat diets.\u00a0 Here are the graphs from the paper.<\/p>\n After going through all the data, Rabast et al conclude<\/p>\n Differences in fluid and electrolyte balance could not be measured but marked fluctuations can occur.\u00a0 However, the change in body water and electrolytes could only be considered in short-term studies as the cause of the differences in weight loss.\u00a0 Variation in the depletion of the glycogen pool is also a feasible explanation, as up to now, sufficiently long-term studies have not been reported.\u00a0 However, the glycogen pool can be restored even under fasting conditions.\u00a0 Therefore, an increased rate of metabolism presents itself as the most feasible explanation<\/em>. [my italics]<\/p>\n<\/blockquote>\n The 1981 Rabast study that AC does comment upon refutes his commentary on the difference being due to greater fluid loss from the low-carb diet.<\/p>\n Potassium excretion during the low-carbohydrate diets was significantly greater for as long as 14 days, but at the end of the experimental period the observed differences no longer attained statistical significance.\u00a0 At no time did the intake and loss of fluid and the balances calculated therefrom show significant differences.\u00a0 From the findings obtained it appears that the alterations in the water and electrolyte balance observed during the low-carbohydrate diets are reversible phenomenon and should thus not be regarded as causal agents.<\/p>\n<\/blockquote>\n As to AC\u0092s comment that the work of Rabast et al should be ignored because it has never been replicated by another group of researchers, I\u0092ll leave to you to decide the validity of that.\u00a0 There have been a number of such studies, including ones (as I\u0092ll describe in a moment) in AC\u0092s own list that confirm what Rabast found.\u00a0 The 1979 Rabast paper discussed earlier lists 17 of them.<\/p>\n Hang in there; we\u0092re almost through.\u00a0 If I have to read all these papers and type all this stuff, the least you can do is stick with me \u0091til the end.<\/p>\n Most of these studies don\u0092t list the amounts of weight lost by the subjects because most of them aren\u0092t designed to really look at weight loss.\u00a0 Most are designed to look at other metabolic parameters such as protein sparing or branch chain amino acid use or nitrogen balance and the authors weren\u0092t particularly interested in how much weight the subjects lost.\u00a0 The authors mention that the two groups of subjects lost similar amounts of weight.\u00a0 Other than the Rabast studies that we\u0092ve already discussed, only four studies listed the weight lost over the course of the study by the subjects on either low-carb or high-carb diets.\u00a0 In none of these cases did the weight loss difference reach statistical significance, so AC is presenting them as if there is no difference.<\/p>\n But in reality, there was a difference.\u00a0 It just wasn\u0092t statistically significant.<\/p>\n Statistical significance as it pertains to weight loss is a function of both number of subjects and amount of weight loss.\u00a0 If I enroll 10 obese subjects in a weight-loss study and put five subjects on one diet and five on another, observe them for four weeks, and find that one group has lost an average of 2 pounds more than the other, that probably won\u0092t be a statistically significant difference.\u00a0 Why?\u00a0 Because with only five subjects in each arm of the study, it requires a much larger weight loss to show a statistically significant difference.<\/p>\n If I do the same exact study, but enroll 100 subjects with 50 in each arm, and get exactly the same results – a two pound differential – then I achieve statistical significance.\u00a0 The more subjects, the smaller the difference in outcomes it takes to reach significance.<\/p>\n In the case of these metabolic ward studies, the numbers of subjects are small.\u00a0 As we\u0092ve discussed, it is extremely expensive to keep subjects hospitalized 24 hours per day.\u00a0 Consequently, most metabolic ward studies don\u0092t enroll very many subjects.<\/p>\n I went through all the papers in AC\u0092s list and found four (aside from the Rabast that we\u0092ve already discussed) that list both starting and ending weights for the subjects.\u00a0 I\u0092ve listed them in the chart below.<\/p>\n As you can see, the study with the largest number of subjects had only 22 subjects in each arm.\u00a0 These studies all use a caloric intake that is lower than would be expected to produce any kind of a metabolic advantage because all are at an almost starvation level.\u00a0 Yet, as you can see, three out of the four show a greater weight loss in the low-carb arm than in the low-fat arm of the study.\u00a0 Equal caloric intake, greater weight loss with the low-carbohydrate diet.\u00a0 But, due to the small number of subjects, the difference doesn\u0092t reach statistical significance.<\/p>\n If we had these same findings and same difference in weight loss between the two diets with a larger number of subjects, we would indeed have a significant difference.\u00a0 If we did a meta-analysis of these studies, we might find that adding the subjects together would end up showing a significantly difference in weight loss.\u00a0 Even though these differences don\u0092t add up to statistical significance given the number of subjects involved, you can see the definite trend.<\/p>\n But what about the Piatti study, the one that showed the low-fat diet producing more weight loss than the low-carb?\u00a0 I have it marked with an asterisk for a reason.\u00a0 The paper by Piatti et al titled Hypocaloric High-Protein Diet Improves Glucose Oxidation and Spares Lean Body Mass: Comparison to Hypocaloric High-Carbohydrate Diet<\/em> looked at how 25 obese women fared in terms of lean body mass and insulin sensitivity.\u00a0 They were put on 800 kcal diets for 21 days.\u00a0 It was found that the low-carb diet spared more muscle tissue and improved insulin sensitivity more than the low-fat diet of an equal number of calories.<\/p>\n Since the authors weren\u0092t specifically studying weight loss, they didn\u0092t really randomize the subjects by weight but did so by other parameters.\u00a0 As it turned out, the group on the low-fat, high-carb diet were much heavier than those that ended up in the low-carb arm.\u00a0 The average starting weight of the subjects in the low-fat arm was 213 pounds (96.8 kg) whereas the starting weight of those on the low-carb arm was 191 pounds (86.8 kg), a significant difference.\u00a0 It would stand to reason that subjects starting off at 213 pounds on a 800 calorie diet would lose more over 21 days than subjects starting out at 191 pounds and following the same diet, and indeed they did.<\/p>\n This post has gone on way, way too long, but I think it\u0092s pretty obvious that these studies fail to \u0091prove\u0092 that a metabolic advantage does not exist.\u00a0 I would say, if anything, that they \u0091prove\u0092 just the opposite.<\/p>\n Just so you can go through these studies yourselves if you so desire, I\u0092ve put them all up on Scribd.\u00a0 The links are below to the full text of all.<\/p>\n The next post will a) be much, much shorter and will b) go into detail on a beautiful study that AC totally disses in his book.\u00a0 We\u0092ll look at his diss and what the study really says.\u00a0 That should put paid to AC.<\/p>\n All the papers referenced by AC listed below.\u00a0 All full text.<\/p>\n Kinsell et al<\/a><\/p>\n Grey Kipnes<\/a><\/p>\n Rabast et al 1979<\/a><\/p>\n Rabast et al 1981<\/a><\/p>\n Yang et al<\/a><\/p>\n Bogardus et al<\/a><\/p>\n Hoffer et al<\/a><\/p>\n Leibel et al<\/a><\/p>\n Vazquez 1992<\/a><\/p>\n Vazquez 1994<\/a><\/p>\n\n
![\"\"](\"http:\/\/www.proteinpower.com\/drmike\/wp-content\/uploads\/2010\/02\/Colpo-Chart2.jpg\" "\\"Colpo")
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\nHere is the sum total of the information given on the \u0091metabolic ward\u0092 status of the first patient described:<\/p>\n\n
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![\"\"](\"http:\/\/www.proteinpower.com\/drmike\/wp-content\/uploads\/2010\/02\/Colpo-studies-blog2.jpg\" "\\"Colpo")
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