Posts Tagged ‘carbohydrate’

Baseball is like church. Many attend. Few understand.

— Leo Durocher.

The movie Moneyball provides an affirmative answer to an important question in literature and drama: can you present a scene and bring out the character of a subject that is boring while, at the same time, not make the presentation boring?  The movie, and  Michael Lewis’sbook that it is based on, are about baseball and statistics!  For fans, baseball is not boring so much as incredibly slow, providing a soothing effect like fishing, interspersed with an occasional big catch. The movie stars Brad Pitt as Billy Beane, the General Manager of the Oakland Athletics baseball team in the 1990s.  A remarkably talented high school athlete, Billy Beane, for unknown reasons, was never able to play out his potential as an MLB player but, in the end, he had a decisive effect on the game at the managerial level. The question is how the A’s, with one-third of the budget of the Yankees, could have been in the play-offs three years in a row and, in 2001, could win 102 games.  The movie is more or less faithful to the book and both are as much about organizations and psychology as about sports. The story was “an example of how an unscientific culture responds, or fails to respond, to the scientific method” and the science is substantially statistical.

In America, baseball is a metaphor for just about everything. Probably because it is an experience of childhood and adolescence, lessons learned from baseball stay with us. Baby-boomers who grew up in Brooklyn were taught by Bobby Thompson’s 1951 home-run, as by nothing later, that life isn’t fair. The talking heads in Ken Burns’s Baseball who found profound meaning in the sport are good examples. Former New York Governor Mario Cuomo’s comments were quite philosophical although he did add the observation that getting hit in the head with a pitched ball led him to go into politics.

One aspect of baseball that is surprising, especially when you consider the money involved, is the extent to which strategy and scouting practices have generally ignored hard scientific data in favor of tradition and lore. Moneyball tells us about group think, self-deception and adherence to habit in the face of science. For those of us who a trying to make sense of the field of nutrition, where people’s lives are at stake and where numerous professionals who must know better insist on dogma — low fat, no red meat — in the face of contradictory evidence, baseball provides some excellent analogies.

The real stars of the story are the statistics and the computer or, more precisely, the statistics and computer guys: Bill James an amateur analyzer of baseball statistics and Paul DePodesta, assistant General Manager of the A’s who provided information about the real nature of the game and how to use this information. James self-published a photocopied book called 1977 baseball abstract: featuring 18 categories of statistical information you just can’t find anywhere else. The book was not just about statistics but was in fact a critique of traditional statistics pointing out, for example, that the concept of an “error;” was antiquated, deriving from the early days of gloveless fielders and un-groomed playing fields of the 1850s. In modern baseball, “you have to do something right to get an error; even if the ball is hit right at you, and you were standing in the right place to begin with.” Evolving rapidly, the Abstracts became a fixture of baseball life and are currently the premium (and expensive) way to obtain baseball information.

It is the emphasis on statistics that made people doubt that Moneyball could be made into a movie and is probably why they stopped shooting the first time around a couple of years ago. Also, although Paul DePodesta (above) is handsome and athletic, Hollywood felt that they should cast him as an overweight geek type played by Jonah Hill. All of the characters in the film have the names of the real people except for DePodesta “for legal reasons,” he says. Paul must have no sense of humor.

The important analogy with nutrition research and the continuing thread in this blog, is that it is about the real meaning of statistics. Lewis recognized that the thing that James thought was wrong with the statistics was that they

“made sense only as numbers, not as a language. Language, not numbers, is what interested him. Words, and the meaning they were designed to convey. ‘When the numbers acquire the significance of language,’ he later wrote, ‘they acquire the power to do all the things which language can do: to become fiction and drama and poetry … . And it is not just baseball that these numbers through a fractured mirror, describe. It is character. It is psychology, it is history, it is power and it is grace, glory, consistency….’”

By analogy, it is the tedious comparison of quintiles from the Harvard School of Public Health proving that white rice will give you diabetes but brown rice won’t or red meat is bad but white meat is not, odds ratio = 1.32. It is the bloodless, mindless idea that if the computer says so, it must be true, regardless of what common sense tells you. What Bill James and Paul DePodesta brought to the problem was understanding that the computer will only give you a meaningful answer if you ask the right question; asking what behaviors accumulated runs and won ball games, not which physical characteristics — runs fast, looks muscular — that seem to go with being a ball player… the direct analog of “you are what you eat,” or the relative importance of lowering you cholesterol vs whether you actually live or die.

As early as the seventies, the computer had crunched baseball stats and come up with clear recommendations for strategy. The one I remember, since it was consistent with my own intuition, was that a sacrifice bunt was a poor play; sometimes it worked but you were much better off, statistically, having every batter simply try to get a hit. I remember my amazement at how little effect the computer results had on the frequency of sacrifice bunts in the game. Did science not count? What player or manager did not care whether you actually won or lost a baseball game. The themes that are played out in Moneyball, is that tradition dies hard and we don’t like to change our mind even for our own benefit. We invent ways to justify our stubbornness and we focus on superficial indicators rather than real performance and sometimes we are just not real smart.

Among the old ideas, still current, was that the batting average is the main indicator of a batter’s strength. The batting average is computed by considering that a base-on-balls is not an official at bat whereas a moments thought tells you that the ability to avoid bad pitches is an essential part of the batter’s skill. Early on, even before he was hired by Billy Beane, Paul DePodesta had run the statistics from every twentieth century baseball team. There were only two offensive statistics that were important for a winning team percentage: on-base percentage (which included walks) and slugging percentage. “Everything else was far less important.” These numbers are now part of baseball although I am not enough of a fan to know the extent to which they are still secondary to the batting average.

One of the early examples of the conflict between tradition and science was the scouts refusal to follow up on the computer’s recommendation to look at a fat, college kid named Kevin Youkilis who would soon have the second highest on-base percentage after Barry Bonds. “To Paul, he’d become Euclis: the Greek god of walks.”

The big question in nutrition is how the cholesterol-diet-heart paradigm can persist in the face of the consistent failures of experimental and clinical trials to provide support. The story of these failures and the usurpation of the general field by idealogues has been told many times. Gary Taubes’s Good Calories, Bad Calories is the most compelling and, as I pointed out in a previous post, there seems to have been only one rebuttal, Steinberg’s Cholesterol Wars. The Skeptics vs. the Preponderance of Evidence. At least within the past ten year, a small group have tried to introduce new ideas, in particular that it is excessive consumption of dietary carbohydrate, not dietary fat, that is the metabolic component of the problems in obesity, diabetes and heart disease and have provided extensive, if generally un-referenced, experimental support. An analogous group tried to influence baseball in the years before Billy Beane. Larry Lucchino, an executive of the San Diego Padres described the group in baseball as being perceived as something of a cult and therefore easily dismissed. “There was a profusion of new knowledge and it was ignored.” As described in Moneyball “you didn’t have to look at big-league baseball very closely to see its fierce unwillingness to rethink any it was as if it had been inoculated against outside ideas.”

“Grady Fuson, the A’s soon to be former head of scouting, had taken a high school pitcher named Jeremy Bonderman and the kid had a 94 mile-per-hour fastball, a clean delivery, and a body that looked as if it had been created to wear a baseball uniform. He was, in short, precisely the kind of pitcher Billy thought he had trained the scouting department to avoid…. Taking a high school pitcher in the first round — and spending 1.2 million bucks to sign — that was exactly this sort of thing that happened when you let scouts have their way. It defied the odds; it defied reason. Reason, even science, was what Billy Beane was intent on bringing to baseball.”

The analogy is to the deeply ingrained nutritional tradition, the continued insistence on cholesterol and dietary fat that are assumed to have evolved in human history in order to cause heart disease. The analogy is the persistence of the lipophobes, in the face of scientific results showing, at every turn, that these were bad ideas, that, in fact, dietary saturated fat does not cause heart disease. It leads, in the end, to things like Steinberg’s description of the Multiple risk factor intervention trial. (MRFIT; It’s better not to be too clever on acronyms lest the study really bombs out): “Mortality from CHD was 17.9 deaths per 1,000 in the [intervention] group and 19.3 per 1,000 in the [control] group, a statistically nonsignificant difference of 7.1%”). Steinberg’s take on MRFIT:

“The study failed to show a significant decrease in coronary heart disease and is often cited as a negative study that challenges the validity of the lipid hypothesis. However, the difference in cholesterol level between the controls and those on the lipid lowering die was only about 2 per cent. This was clearly not a meaningful test of the lipid hypothesis.”

In other words, cholesterol is more important than outcome or at least a “diet designed to lower cholesterol levels, along with advice to stop smoking and advice on exercise” may still be a good thing.

Similarly, the Framingham study which found a strong association between cholesterol and heart disease found no effect of dietary fat, saturated fat or cholesterol on cardiovascular disease.  Again, a marker for risk is more important than whether you get sick.  “Scouts” who continued to look for superficial signs and ignore seemingly counter-intuitive conclusions from the computer still hold sway on the nutritional team.

“Grady had no way of knowing how much Billy disapproved of Grady’s most deeply ingrained attitude — that Billy had come to believe that baseball scouting was at roughly the same stage of development in the twenty-first century as professional medicine had been in the eighteenth.”

Professional medicine? Maybe not the best example.

What is going on here? Physicians, like all of us, are subject to many reinforcers but for humans power and control are usually predominant and, in medicine, that plays out most clearly in curing the patient. Defeating disease shines through even the most cynical analysis of physician’s motivations. And who doesn’t play baseball to win. “The game itself is a ruthless competition. Unless you’re very good, you don’t survive in it.”

Moneyball describes a “stark contrast between the field of play and the uneasy space just off it, where the executives in the Scouts make their livings.” For the latter, read the expert panels of the American Heat Association and the Dietary Guidelines committee, the Robert Eckels who don’t even want to study low carbohydrate diets (unless it can be done in their own laboratory with NIH money). In this

“space just off the field of play there really is no level of incompetence that won’t be tolerated. There are many reasons for this, but the big one is that baseball has structured itself less as a business and as a social club. The club includes not only the people who manage the team but also in a kind of women’s auxiliary many of the writers and commentators to follow and purport to explain. The club is selective, but the criteria for admission and retention and it is there many ways to embarrass the club, but being bad at your job isn’t one of them. The greatest offense a club member can commit is not ineptitude but disloyalty.”

The vast NIH-USDA-AHA social club does not tolerate dissent. And the media, WebMD, Heart.org and all the networks from ABCNews to Huffington Post will be there to support the club. The Huffington Post, who will be down on the President of the United States in a moment, will toe the mark when it comes to a low carbohydrate story.

The lessons from money ball are primarily in providing yet another precedent for human error, stubbornness and, possibly even stupidity, even in an area where the stakes are high. In other words, the nutrition mess is not in our imagination. The positive message is that there is, as they say in political science, validator satisfaction. Science must win out. The current threat is that the nutritional establishment is, as I describe it, slouching toward low-carb, doing small experiments, and easing into a position where they will say that they never were opposed to the therapeutic value of carbohydrate restriction. A threat because they will try to get their friends funded to repeat, poorly, studies that have already been done well. But that is another story, part of the strange story of Medicineball.

“Portion Control” is a popular buzz-word in nutrition. It has a serious and somewhat quantitative sound as if it were recently discovered and transcends what it really means which is, of course, self-control. Self-control has been around for long time and has a poor history as a dieting strategy.  Lip service is paid to how we no longer think that overeating means that you are a bad person but “portion control” is just the latest version of the moralistic approach to dieting; the sense of deprivation that accompanies traditional diets may be one of the greatest barriers to success. Getting away from this attitude is probably the main psychological benefit of low-carbohydrate diets.  “Eat all the meat you want” sounds scary to the blue-stockings at the USDA but most people who actually use such diets know that the emphasis is on “want” and by removing the nagging, people usually find that they have very little desire to clean their plate and don’t eat any more meat than they ever did.  Coupled with the satiety of fat and protein compared to carbohydrate, this is surely a major factor in the success of carbohydrate restriction.  In the big comparison trials, the low-fat trials are constrained to fix calories while the low-carbohydrate group is allowed to eat ad-libitum, and the two groups usually come out about the same total calories.

On the other hand, there is an obvious benefit to having a lean and hungry feel if not look and, as Woody Allen might have put it: eating less is good if only for caloric reasons.  So, one tactic in a low carbohydrate diet is to eat a small portion — say, one fried egg, a small hamburger — and then see if you are still hungry before having the second or third portion which while not forbidden, is also not required. The longer you wait between portions, the more satiety sets in.

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“Doctors prefer large studies that are bad to small studies that are good.”

— anon.

The paper by Foster and coworkers entitled Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet, published in 2010, had a surprisingly limited impact, especially given the effect of their first paper in 2003 on a one-year study.  I have described the first low carbohydrate revolution as taking place around that time and, if Gary Taubes’s article in the New York Times Magazine was the analog of Thomas Paine’s Common Sense, Foster’s 2003 paper was the shot hear ’round the world.

The paper showed that the widely accepted idea that the Atkins diet, admittedly good for weight loss, was a risk for cardiovascular disease, was not true.  The 2003 Abstract said “The low-carbohydrate diet was associated with a greater improvement in some risk factors for coronary heart disease.” The publication generated an explosive popularity of the Atkins diet, ironic in that Foster had said publicly that he undertook the study in order to “once and for all,” get rid of the Atkins diet.  The 2010 paper by extending the study to 2 years would seem to be very newsworthy.  So what was wrong?  Why is the new paper more or less forgotten?  Two things.  First, the paper was highly biased and its methods were so obviously flawed — obvious even to the popular press — that it may have been a bit much even for the media. It remains to be seen whether it will really be cited but I will suggest here that it is a classic in misleading research and in the foolishness of intention-to-treat (ITT).

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“The truth?  If I wanted the truth, I would have called Sixty Minutes.”

— Spiros Focás in Jewel of the Nile.

Sugar is an easy target. These days, if you say “sugar” people think of Pop-Tarts® or Twinkies®, rather than pears in red wine or tamagoyaki the traditional sweet omelet that is a staple in Bento Boxes.  Pop-Tarts® and Twinkies® are especially good targets because, in addition to sugar (or high fructose corn syrup (HFCS), they also have what is now called solid fat (the USDA thinks that “saturated” is too big a word for the average American ) and the American Heart Association and other health agencies are still down on solid fat.  Here’s a question, though: if you look on the ingredients list for Twinkies®, what is the first ingredient, the one in largest amount?  (Answer at the end of this post).

The Threat

What went wrong in the obesity epidemic?  There is some agreement that by focussing on fat, the nutritional establishment gave people license to over-consume carbohydrates. The new threat is that by focusing now on fructose, the AHA and USDA and other organizations are giving implicit license to over-consume starch — almost guaranteed since these agencies are still down on fat and protein.  The additional threat is that by creating an environment of fructophobia, the only research on fructose that will be funded are studies at high levels of total carbohydrate where, because of the close interaction between glucose and fructose, deleterious effects are sure to be found. The results will be generalized to all conditions.  Like lipophobia, there will be no null hypothesis.

The latest attack on sugar and on fructose itself (sugar and HFCS are half fructose) comes from Robert Lustig, a pediatrician at University of California San Francisco. His lecture describing fructose as a virtual poison got more than a million and a half hits on YouTube.  The presentation has an eponymous style (Lustig, Ger. adj., merry, amusing, e.g. Die Lustige Witwe, The Merry Widow) and includes a discussion of the science bearing on fructose metabolism. While admitting the limitations of that science, even Gary Taubes was worried. Comments on YouTube and other sites say they liked the science but did not agree with his recommendations — it will turn out that he now wants government control of sugar consumption, especially for my kid and yours.

The presentation of the science is compelling but, while it has a number of important points, it is clearly biased and, oddly, a good deal of it is totally wrong, some of it containing elementary errors in chemistry that border on the bizarre — how hard would it have been to open an elementary organic chemistry text?  In trying to draw parallels between alcohol and fructose, Lustig says “ethanol is a carbohydrate.” Ethanol is not a carbohydrate.  A horse is not a dog. If you said that ethanol is a carbohydrate in sophomore Organic Chemistry, you would get it wrong. Period. No partial credit. Such elementary errors compromise the message and raise the question in what way Lustig is an expert in this field.  It gets worse.

It is biological function that is important and ethanol is not processed like fructose as Lustig says. There is very little chemical sense in saying that ethanol and fructose are processed biologically in similar ways.  And a metabolic pathway is shown in which glycogen is absent. Glycogen is the storage form of glucose and is generally taken as a good thing because of its relation to endurance in athletes but, like fat, glycogen is a storage form of energy and having a lot is not always a good thing.  In any case, it is not true that fructose does not give rise to glycogen.  In fact, fructose is generally better at forming glycogen than glucose is.  This is especially true when you consider the effect of exercise which is why Gatorade® may actually be a good thing if you are in a football game rather than watching one. This is the general error in Lustig’s talk.  Metabolism is not static and has evolved to deal with changing conditions of diet and environment. A metabolic chart, like any map only tells you where you can go, not whether you go there. And the notable absence in Lustig’s talk is data.

It is possible that  sugar and ethanol have behavioral effects  in common but this is not due to similarities in metabolism.  And even the behavioral effects are not settled within the psychology community; alcoholism is far different from “sugar addiction,” if there is such a thing; polishing off the whole container of Häagen-Dazs® may not technically qualify as addictive behavior.

The Threat of Policy

All of this might be okay — Lustig’s lecture was not a scientific treatise — except that he has gone to the next step.  Convinced of the correctness of his analysis, he wants government intervention to control sugar and sweeteners in some way .  There is an obvious sense of deja-vu as another expert attempts to use the American population as Guinea pigs for a massive population experiment, like the low fat fiasco under which we still suffer. It is not just that we got unintended consequences (think margarine and trans-fats) but rather that numerous people have pointed out that the science was never there for low-fat to begin with (brilliantly explained in Fat Head).  In other words leaving aside the question of when we should turn science into policy, is the science any good?

Fructose

It is important to understand that fructose is not a toxin. It is a normal metabolite. If nothing else, your body makes a certain amount of fructose.  Fructose, not music (the food of love), is the preferred fuel of sperm cells. Fructose formed in the eye can be a risk but its cause is generally very high glucose. Fructose is a carbohydrate and is metabolized in ways similar to, if different in detail, from glucose but a substantial amount (can be 60 %) of fructose is turned to glucose — that is why the glycemic index of fructose is 20 and not zero.

The extent to which fructose metabolism has a uniquely detrimental effect is strongly dependent on conditions.  Fructose may be worse than glucose under conditions of very high carbohydrate intake but its effect will change as total carbohydrate is lowered. And since carbohydrate across the board is what is understood to be the problem — Lustig states that clearly in his YouTube — policy would suggest that that is the first line of attack on health — reduce carbohydrate (emphasizing fructose if you like) but as carbohydrate and calories are reduced, any effect of fructose will be minimized.  In the extreme, if you are on a very low carbohydrate diet, any fructose you do eat is likely to be turned into glucose.

The Opportunity

Lustig makes his case against fructose in terms of fundamental biochemistry which is really how it should be.  Can biochemistry be explained to the general population?  Can the problem be explained in a simple but precise way so that we really have the sense of talking about science and not politics?  So what is needed is somebody who actually knows biochemistry.  Maybe somebody with experience in teaching biochemistry to future doctors.  Hey, that’s my job description.  In fact, I’m going to try that in the next few blogs and on YouTube. I and others have  taught courses that try to reduce the three year sequence that professional chemists follow: general chemistry-organic chemistry-biochemistry.  I will try to give everybody a window into organic chemistry, biochemistry and metabolism. In fact, that might be a good focus for government intervention. Instead of punishing the patient, how about funding for teaching biochemistry to the public. For the moment, though, let’s look at some population data.

Sweetener Consumption.

What about sweeteners?  Well, of course, consumption has gone up. Surprisingly, not as much as one would have thought.  According to the USDA about 15 %.  One question is whether this increase is disproportionately due to fructose. The figures below show that, in fact, the ratio of fructose to glucose has remained constant over the last 40 years.  (The deviation from 1:1 which would be expected for pure sucrose or HFCSA, is due to a  relatively constant 20 % or so of pure glucose that  is used in sweetening in the food industry). It is possible that, although the ratio is the same, that the absolute increase in  fructose has a worse effect than the increased glucose but, of course, you would have to prove it.  The figures suggest, however, that you will have to be careful in determining whether the effect of increased sweetener is due to fructose or glucose, or the effect of one on the other, or the effect of insulin and other hormones on both.  An unrestrained, lustige, lack of anything careful is exactly the current threat.

Answer to “puzzler:” The main ingredient in Pop-Tarts® and Twinkies® is flour. Some people say that if you add up the different forms of sugar that will be greater but like all ideas derived from Lustig, there is an advantage in looking at the data: 38 g. of carbohydrate, 17 g. of sugars.

“Headlines” is one of Jay Leno’s routines on The Tonight Show. While low on production values, it provides amusing typos, odd juxtapositions of text and inappropriate couplings from real notices and newspapers. The headlines are frequently very funny since, like fiction in general, authored comedy has to be plausible. There have been many other versions of the same idea including items in the New Yorker but Jay Leno’s audience rapport adds to the impact. Expert as he is, though, Jay seemed a little off guard when nobody laughed at the headline: “The Diabetes Discussion Group will meet at 10 AM right after the pancake breakfast.” It’s probably generational. After 30 or so years having the American Diabetes Association tell you that sugar is Ok as long as you “cover it with insulin” and that diabetes, a disease of carbohydrate intolerance, is best treated by adding carbohydrate and reducing fat, who knows what anybody believes.

One of the headlines on a previous show that did get a laugh said: “To increase gas mileage, drive less.”  (If Jay only knew how much we spent to get the USDA committee to come up with the advice that if you want to lose weight, you should eat less).

“.. Have we eaten on the insane root,
That takes the reason prisoner?”
— William Shakespeare, Macbeth.

For tragic humor in the bizarre field of diabetes information, it is really hard to compete. About the same time as the headlines sequence on the Tonight Show, DiabetesHealth  an organization and website that is intended to “investigate, inform, inspire” produced an inspiring investigation from the literature. The story is entitled “Maple Syrup – A Sweet Surprise.”  You gotta’ read this:

 “Meet the latest superfood: maple syrup.  Wait a minute…maple syrup? The super-sugary stuff poured on pancakes and waffles and used to glaze hams? That maple syrup? That’s right. Researchers from the University of Rhode Island have discovered that the syrup-produced in the northeastern United States and Canada–contains numerous compounds with real health benefits.”

So how did people with diabetes fare on the maple syrup? Well, there were no people. Or animals. The researchers did not test the effect of consumed maple syrup but only chemically analyzed samples of the stuff.

“‘In our laboratory research, we found that several of these compounds possess anti-oxidant and anti-inflammatory properties, which have been shown to fight cancer, diabetes, and bacterial illnesses,’ said Navindra Seeram, an assistant professor of pharmacognosy (the study of medicines derived from natural sources) at the university and the study’s lead author”

“Pharmacognosy,” incidentally, is the only English word correctly pronounced through the nose.  The article indicates that “a paper describing their results will appear in the Journal of Functional Foods. Scientists hope that these discoveries could lead to innovative treatments as the beneficial substances are synthesized to create new kinds of medicine.”  The article, however, is nothing if not circumspect:

“You might want to pause for a moment before rushing out and buying jug after jug of Canada’s finest maple syrup, though. It still contains plenty of sugar,…” In fact, by far the major ingredient in maple syrup is sucrose which, again, only has to be “covered” with insulin. So, with all those beneficial compounds, we will need less insulin per gram of sucrose with maple syrup, right?    Would Jay Leno have gotten a laugh if the diabetes meeting followed the pancakes and maple syrup breakfast?  How about if they were whole grain pancakes?

“If you can look into the seeds of time,
And say which grain will grow, and which will not…”
— William Shakespeare, Macbeth.

Not to be outdone, the American Diabetes Association website offers the lowdown on just how good grain is. Fiber, in general, is so good for you that you should be careful not to snarf it up too fast. As they point out, it is “important that you increase your fiber intake gradually, to prevent stomach irritation, and that you increase your intake of water and other liquids, to prevent constipation.” Doesn’t really sound all that healthy but foods with fiber “have a wealth of nutrition, containing many important vitamins and minerals.” Now, vitamin deficiency has always seemed to me to be the least of our nutritional problems but there’s more: “In fact,” using fact in its non-traditional meaning, fiber “may contain nutrients that haven’t even been discovered yet!” (their exclamation point). Not to belabor all the metaphors here, the ADA, long telling us that people with diabetes deserve to have their carbs, are surely offering pie in the sky.


The big news in the low carb world is that Consumer Reports has published, for the first time, faint praise for the Atkins diet. However, the vision one might have of CR employees testing running shoes on treadmills doesn’t really apply here. They did not put anybody on a diet, even for a day. They didn’t have to. They have the standards from the government. Conform to the USDA Guidelines and CR will give you thumbs up. It probably doesn’t matter since, these days, most people buy a food processor by checking out the reviews on the internet — there are now many reviews online of what it’s like to actually be on a low-carbohydrate diet, so rather than follow CR’s imaginings of what it’s like, you can check out what users say — Jimmy Moore, Tom Naughton and Laura Dolson together get about 1.5 million posts per month with many tests and best buy recommendations. What caught my eye, though, is the ubiquitous Dean Ornish; the ratio of words written about the Ornish diet to the number of people who actually use it is probably closing in on a googol (as it was originally spelled). The article says: “to lose weight, you have to burn up more calories than you take in, no matter what kind of diet you’re on. ‘The first law of thermodynamics still applies,’ says Dean Ornish, M.D.

That’s how I got into this field. My colleague Gene Fine, and I published our first papers in nutrition on the subject of metabolic advantage and thermodynamics and we gave ourselves credit for reducing the number of people invoking laws of thermodynamics. “Metabolic advantage” refers to the idea that you can lose more weight, calorie-for-calorie on a particular diet, usually a low-carbohydrate diet. (The term was used in a paper by Browning to mean the benefits in lipid metabolism of a low-carbohydrate diet, but in nutrition you can re-define anything you want and you don’t have to cite anybody else’s work if you don’t want to). The idea of metabolic advantage stands in opposition to the idea that “a calorie is a calorie” which is, of course, the backbone of establishment nutrition and all our woe. As in the CR article, whenever the data show that a low-carbohydrate diet is more effective for weight loss, somebody always jumps in to say that it would violate the laws of thermodynamics. Those of us who have studied or use thermodynamics recognize that it is a rather difficult subject — somebody called it the physics of partial differential equations — and we’re amazed at how many experts have popped up in the nutrition field.

Finding the right diet doesn’t require knowing much thermodynamics but it is an interesting subject and so I’ll try to explain what it is about and how it’s used in biochemistry. The physics of heat, work and energy, thermodynamics was developed in the nineteenth century in the context of the industrial revolution — how efficiently you could make a steam engine operate was a big deal.  Described by Prigogine as the first revolutionary science, it has some interesting twists and intellectual connections. The key revolutionary concept is embodied tin the second law which describes the efficiency of physical processes.  It has broad philosophical meaning.  The primary concept, the entropy, is also used in communication and  the content of messages in information theory.  The entropy of a message is, in one context, how much a message has been garbled in transmission.  The history of thermodynamics also has some very strange characters, besides me and Gene, so I will try to describe them too.

First, we can settle the question of metabolic advantage, or more precisely, energy inefficiency. The question is whether all of the calories in food are available for weight gain or loss (or exercise) regardless of the composition of the diet. Right off, metabolic advantage is an inherent property of higher protein diets and low carbohydrate diets. In the first case, the thermic effect of feeding (TEF) is a measure of how many of the calories in food are wasted in the process of digestion, absorption, low-level chemical transformation, etc. TEF (old name: specific dynamic action) is well known and well studied. Nobody disputes that the TEF can be substantial for protein, typically 20 % of calories. It is much less for carbohydrate and still less for fat. So, substituting any protein for either of the other macronutrients will lead to energy inefficiency (the calories will be wasted as heat). A second unambiguous point is that in the case of low-carbohydrate diets, in order to maintain blood glucose, the process of gluconeogenesis is required. You learn in biochemistry courses that it requires a good deal of energy to convert protein (the major source for gluconeogenesis) into glucose.

So, right off, metabolic advantage or energy inefficiency is known and measurable. Critics of carb restriction as a strategy admit that it occurs but say that it is too small in a practical sense to be worth considering when you are trying to lose weight. These are usually the same people who tell you that the best way to lose weight is through accumulation of small changes in daily weight loss by reducing 100 kcal a day or something like that. In any case, there is a big difference between things that are not practical or have only small effects and things that are theoretically impossible. If metabolic advantage were really impossible theoretically, that would be it. We could stop looking for the best diet and only calories would count. Since we know energy inefficiency is possible and measurable, shouldn’t we be trying to maximize it.  But what is the story on thermodynamics? What is it? Why do people think that metabolic advantage violates thermodynamics? What is their mistake? More specifically, doesn’t the first law of thermodynamics say that calories are conserved? Well, there is more than one law of thermodynamics and even the first law has to be applied correctly. Let me explain. (Note in passing that the dietary calorie is a physical kilocalorie (kcal; 1000 calories).

There are four laws of thermodynamics. Two are technical. The zeroth law says, in essence, that if two bodies have the same temperature as a third, they have the same temperature as each other. This sounds obvious but, in fact, it is an observational law — it always turns out that way. The law is necessary to make sure everything else is for real. If anybody ever finds an experimental case where it is not true, the whole business will come crashing down. The third law describes what happens at the special condition known as the absolute zero of temperature. In essence, the zeroth and third laws, allow everything else to be calculated and practical thermodynamics like bioenergetics pretty much assumes it in the background.

The second law is what thermodynamics is really about — it was actually formulated before the first law — but since the first law is usually invoked in nutrition, let’s consider this first. The first law is the conservation of energy law. Here’s how it works: thermodynamics considers systems and surroundings. The thing that you are interested in — living system, a single cell, a machine, whatever, is called the system — everything outside is the surroundings or environment. The first law says that any energy lost by the system must be gained by the environment and any energy taken up by the system must have come from the environment. Its application to chemical systems, which is what applies to nutrition, is that we can attribute to chemical systems, a so-called internal energy, usually written with symbol U (so as not to confuse it with the electrical potential, E). In thermodynamics, you usually look at changes, and the first law says that you can calculate ΔU, the change in U of a system, by adding up the changes in heat added to the system and work done by the system (you can see the roots of thermo in heat machines: we add heat and get work). In chemical systems, the energy can also change due to chemical reactions. Still, if you add up all the changes in the system plus the environment, all the heat, work and chemical changes, the energy is neither created nor destroyed. It is conserved.

Now, why doesn’t the first law apply to nutrition the way Ornish thinks it does? To understand this, you have to know what is done in chemical thermodynamics and bioenergetics, (thermo applied to living systems). If you want to. In nutrition, you can make up your own stuff. But, if you want to do what is done in chemical thermodynamics, you focus on the system itself, not the system plus the environment. So, from the standpoint of chemical thermodynamics, the calories in food represent the heat generated by complete oxidation of food in a calorimeter.

In a calorimeter, the food is placed in a small container with oxygen under pressure and ignited. The heat generated is determined from the increase in temperature of the water bath. (Before the food measurement, we determine the heat capacity of the water bath, that is, how much heat it takes to raise the temperature). The heat is how we define the calories in the food. The box around the sample in the figure shows that we are measuring the heat produced by the system, not the system plus the environment, that is, not applying the first law. If you applied the first law, the calories associated with the food would be zero, because any heat lost in combustion of the food would show up in the water bath of the calorimeter. The calories per gram of carbohydrate would be 0 instead of 4, the calories per gram of fat would be 0 not 9, etc. So, in studying reactions in chemical thermodynamics, energy is not conserved, it is dissipated. When systems dissipate energy, the change is indicated with a minus sign, so for oxidation of food, generally: ΔU < 0. So, no, the first law does not apply. That’s one of the reasons that “a calorie is not a calorie.”
There is an additional point that we assumed in passing. In chemical thermodynamics, the energy goes with the reaction, not with the food. It is not like particle physics where we give the mass of a particle in electron-volts, a measure of energy, because of E=mc2. What this means, practically, is that the 4 kcal per gram of carbohydrate is for the reaction of complete oxidation. Do anything else, make DNA, make protein and all bets are off.
The bottom line is that, contrary to what is usually said, thermodynamics does not predict energy balance and we should not be surprised when one diet is more or less efficient than another. In fact, the question to be answered is why energy balance is ever found. “A calories is a calorie” is frequently what is observed (although there is always a question as to how we make the measurement). The answer is that insofar as there is energy balance, it is a question of the unique behavior of living systems, not physical laws. Two similar subjects of similar age and genetic make-up may, under the right conditions, respond to different diets so that most of what they do is oxidize food and the contributions of DNA or protein synthesis, growth, etc. may be similar and may cancel out so that the major contribution to energy exchange is the heat of combustion.
But thermodynamics is really not about the first law which, while its history is a little odd, it is not revolutionary. Intellectually, the first law is related to conservation of matter. Thermodynamics is about the second law. The second law says that there is a physical parameter, called the entropy, almost always written S, and the change in entropy, ΔS, in any real process, always increases. In ideal, theoretical processes, ΔS may be zero, but it never goes down. In other words, looking at the universe, (any system and its surroundings), energy is conserved but entropy increases. The first law is a conservation law but the second law is a dissipation law. We identify the entropy with the organization, order or information in a system. Systems proceed naturally to the most probable state. In one of the best popular introductions to the subjects, von Baeyer’s Warmth Disperses and Time Passes, entropy is described in terms of the evolution of the organization of his teenage daughter’s room.  To finish up on calorimeters, though, there is Lavoisier’s whole animal calorimeter.

One of Lavoisier’s great contributions was to show that combustion was due to a combination with oxygen rather than the release of a substance, then known as the phlogiston. Lavoisier had the insight that in an animal, the combination of oxygen with food to produce carbon dioxide was the same kind of process. The whole animal calorimeter was a clever way to show this. The animal is placed in the basket compartment f. The inner jacket, b, is packed with ice. The outer jacket, a, is also packed with ice to keep the inner jacket, cold. The heat generated by the animal melts the ice in the inner jacket which is collected in container, Fig 8. Lavoisier showed that the amount of carbon dioxide formed was proportional to the heat generated as it would be if an animal were carrying out the same chemical reactions that occur, for example, in burning of charcoal. “La vie est donc une combustion.” His collaborator in this experiment was the famous mathematician Laplace and people sometimes wonder how he got a serious mathematician like Laplace to work on what is, well, nutrition. It seems likely that it was because Laplace owed him a lot of money.

The study of metabolic pathways provides an insight into chemical reactions and the way they function in living systems but, in the end, even a biochemistry professor still has to answer the question  “What should I eat.”  Adam Cambell, an editor at Men’s Health magazine once asked me: “You’ve just had a meal that conforms to your idea of good nutrition and satisfying portions of food but you’re still hungry.  What should you do?”

“Think of a perfectly-cooked juicy steak or perfectly-prepared fish, or some similar high protein food that you usually like,” I suggested.  “If that sounds good, you’re hungry and you should eat something.  If it doesn’t sound good, you’re not hungry.  You may want desert.  You may want something feeling good in your mouth, but you’re not hungry.” What I meant, of course, is that foods that are high in protein, and lower in carbohydrate, tend to be more filling. This satiating effect of protein is well-known in the biochemical literature and is one of the advantages of diets that restrict carbohydrates and keep protein high.  The fact that protein is satisfying also means that it provides its own control over intake and, for that reason, “concerns” about high protein intake that you hear from nutritional expert are not usually a real problem.  In the obesity epidemic where there was a large increase in carbohydrate consumption and a general decline in fat consumption, protein stayed about the same.  When nutritionists carry out experiments in which people can eat freely, they generally do not change their protein consumption.  In fact, it now seems likely that most people are not getting enough protein.  Recent studies show that people benefit from replacing carbohydrate in their diet with protein, the benefit is in better weight control, in an improved ratio to lean body mass compared to fat and in better control of blood insulin and glucose.  I will describe some of the features of this problem with references to papers in the scientific literature that are either open access or have been made publicly available and public and do not require a subscription.

Nutritionists who study protein think that we need modification of official recommendations for protein consumption.  Donald Layman at the University of Illinois has reviewed some of the important research on this question and he came up with several important points:

•    Protein is a critical part of the adult diet. Beyond physical growth which is only important for a brief period in your life, there is a continuing need to repair and remodel muscle and bone

•    Protein needs for adults relate to body weight not, as you sometimes see, as a per cent of total calories. So, if you are reducing calories, protein needs to stay high and may be a higher percentage of total calories. In choosing a diet, you should establish the grams of protein first.

•    The amount of protein at each meal can be important.  Research indicates that an ideal is 30 g of protein per meal although this may not be practical for everybody. It is recommended that breakfast be high in protein.

•    Most adults benefit from protein intakes above the minimum RDA (recommended daily allotment) and this is especially true for an aging population with increased risks of poor health.  The RDA represents a minimum daily intake for active healthy adults but most people will benefit from replacing at lest some carbohydrate in the diet with protein.

The full story on protein recommendations can be found at Nutrition & Metabolism (no subscription required.

A look at the science

Proteins are generally more complicated molecules than fat or carbohydrate.  Like starch, they are polymers (think chain of beads).  Most starches are homopolymers (all the beads are the same, glucose in this case), but protein molecules are made of 20 different kinds of beads (amino acids).  About half are interchangeable or can be made from other nutrients and are said to be non-essential.  The other half are required in the diet and are said to be essential amino acids, or, for some reason, the more modern term is indispensable.  Now your body is continually breaking down and re-synthesizing its own proteins, the most obvious function of dietary protein is supplying amino acids to replenish body proteins so high quality dietary proteins will be those that supply all the essential amino acids.  Meat, fish and eggs are high quality proteins but combinations of vegetables can also supply the full complement of amino acids.  Many web sites and other sources will give you information about how vegetables can be combined to supply amino acids, but there is another aspect of protein nutrition that should be considered.  Amino acids, like carbohydrate are not just sources of cell material but may have a signaling function.  Remember that it is not just that glucose supplies energy but that it stimulates the release of insulin which further controls metabolism.  Amino acids also perform this function and stimulate insulin release and trigger other physiologic processes, in particular, synthesis of new body protein and provide control over blood glucose.  One essential amino acid in particular, leucine, is of greatest importance in this role.  In comparative studies, diets that are high in leucine improve the ratio of lean body mass to fat. Whey and other milk proteins are particularly high in leucine; red meat is also a good source.

The benefit in substituting protein for carbohydrate is greatest for people with diabetes.  The studies from the laboratories of Mary Gannon and Frank Nuttall are pretty remarkable and I show you a picture of the actual results from their experiments.  They studied the effect of reducing dietary carbohydrate on responses of people with diabetes.  The figure shows that after 5 weeks on a diet with 20 % available glucose (circles in the figure), the response to meals is drastically improved compared to the response if the traditional diet is continued (triangles).  As the diet proceeded, hemoglobin A1c was also reduced.  Gannon and Nuttall have also showed that diets with slightly higher glucose may be effective but the response depends on how much glucose is in the diet.  A very important feature of the studies of this study is that the diets were designed so that patients maintained their weight, in other words, benefit accrued even though no weight was lost.  Given how hard it is to lose weight, this has to be considered a real plus for the higher protein, lower carbohydrate diet.  You can see the whole study, again, without subscription here.

Is there a danger of too much protein?

How many times have you read an article in the media, or even in the medical literature, warning you about the dangers of high protein diets for your kidneys, or for kidney stones, or whatever.   Probably quite a few.  Are they for real?  To answer that question, think of how often you have read an article in the media describing somebody who actually had kidney problems or stones due to a high protein diet? That number is zero or close (there’s always a case study someplace with an isolated patient).

To understand the danger in a high protein diet for people with normal kidneys, consider the following conversation I had with an expert on kidney disease when I was the editor of Nutrition & Metabolism.

RF: I received a manuscript today that rather strongly and categorically says that there is no danger in high protein diets for people with normal kidneys.

Nephrologist: That’s right.

RF: It is?  Can we document that?

N: How do you document that there are no people with three eyes.  We have looked very hard for it and we never found it.

So, what’s wrong.  Mostly what’s wrong is that we never got around to agreeing on what high protein is.  Diets that encourage you to replace carbohydrate with protein are only trying to counteract the high carbohydrate message. Few people actually eat huge amounts of protein.  As discussed above, protein tends to be more satisfying than carbohydrate and what might be considered high protein is pretty average.

In other words, there is common sense.  A healthy high protein diet is currently estimated to have a daily intake of about 1 to 4 g of protein for every kg (2.2 lbs) of body weight while the USDA recommendation is only 0.8 g/kg).  So, if you weigh 175 lbs., an optimal level of protein will be at least 80.  The diet shown below is actually quite a bit higher. Is this really unusual?  In fact, if you ate 3 eggs or even bigger portion of  brisket, do you think something terrible will happen.  Is this dangerous?  To say that normal eating, even with occasional over-indulgence, is dangerous requires real proof and that’s what’s always been missing.

Finally, it is likely that for people with diabetes, there is great danger to kidneys from continued high blood sugar and most physicians would say that this risk is real while any risk from high protein is conjecture.

The bottom line: Substituting protein for carbohydrate in the diet improves blood glucose and insulin control.  As part of a weight loss diet, higher protein preserves lean mass compared to higher carbohydrate diets but the benefits of higher protein, lower carbohydrate diets provide benefit even in the absence of weight loss.