Sunday, October 26, 2014

Energy Balance: Neither Hypothesis Nor Trivial Tautology

In an article published in the British Journal of Medicine, Gary Taubes claimed that what he calls the energy balance “notion” is both a hypothesis and an uninformative tautology.  In this article I will show that the energy balance equation is not a hypothesis nor uninformative tautology.

Hypothesis and Uninformative Tautology?  Source: CDC


Taubes wrote:

"Since the 1950's, the conventional wisdom on obesity has been simple: it is fundamentally caused by or results form a net positive energy balance––another way of saying that we get fat because we overeat.  We consume more energy than we expend." 

Directly under the heading "Energy balance hypothesis" he goes on:

“Despite its treatment as gospel truth, as preordained by physical law, the energy balance or overeating hypothesis of obesity is only that, a hypothesis.”

Thus, he appears to maintain that the idea that organisms gain weight because they consume more energy than they expend is only a hypothesis.  This implies that in his view, it is hypothetically possible for an organism to gain body mass without sustaining a net positive energy balance.

Maybe it is also possible for me to gain in wealth without sustaining a net positive income balance?  Wouldn't it be great if you could grow your bank account while spending more than you earn?  Did the editors of the BMJ really believe that Taubes discovered some new laws of nature and mathematics?

To understand why the energy balance equation is not a hypothesis, we need to understand 1) the concept of hypothesis and 2) the first law of thermodynamics.

A hypothesis is a speculative explanation for a phenomenon, generally based on observation of the behavior of the phenomenon in question.  A hypothesis is potentially falsifiable. 

For example, based on observations, I may speculate that diets containing 25% plant protein are more satiating than diets containing 5% plant protein. I can state all hypotheses in “maybe” statements, e.g. “Maybe diets containing 25% protein are more satiating that diets containing only 5% protein.” I can then construct an experiment to test my hypothesis.  The results of the experiment may confirm or cast doubt on my hypothesis.

Thus, if the energy balance equation is merely a hypothesis, scientists would state it as follows:

"Maybe changes in body mass equal the difference between net energy intake and net energy expenditure."

In addition, if this is a hypothesis, as claimed by Taubes, scientists should be engaged in attempts to test or refute it, and it should be possible to create an experiment which could produce a result that would refute it. 

Regarding the first alternative, it is quite obvious scientists do not use the energy balance equation as a “maybe” statement.  As a matter of fact, scientists state the energy balance equation in mathematical form as follows: 

ΔEbm = Ei – Ee

Where Ebm is the energy stored in body mass, Ei  is energy intake, and Ee is energy expenditure. 

Translated to prose, this equation states:

Any change in body energy stores is equal to energy intake minus energy expenditure.

Furthermore, no scientist is spending his/her time testing and attempting to refute the energy balance equation.  On the contrary, this equation is assumed and used as the very basis for investigating and shedding light upon the various processes that affect net energy intake and expenditure.

Now, someone might say that scientists are supposed to question every thing and not assume anything.  So the question arises, do scientists need to test this energy balance equation before assuming and using it in their investigations? 

To answer this question we need to understand the law of conservation of mass and energy.

The conservation law of thermodynamics states that neither energy nor mass is created or destroyed in any physical process.  Although this law may look like a hypothesis –– which would be stated “maybe energy and mass are conserved in all physical changes” –– in actuality it is not potentially falsifiable because it is in principle impossible for any experiment to refute the law. 

Refutation of this law would require an experiment during which some bit of either energy or mass was ether created out of nothing –– that is, independent of change in any other phenomena –– or destroyed without residue or leaving any trace––that is, again, independent of changing any other, related phenomena.  I would have to either produce or annihilate some thing without transforming any other thing. 

It is in principle impossible to create or observe such an event, because it is the very nature of things (phenomena) to be dependent upon and derived from (transformations of) other, related things.  A observable thing that arises or disappears independent of changes in other things is logically impossible and in principle unobservable.

Basically, any appearance can be viewed as a type of increase, whereas any disappearance can be understood as a species of decrease.  It is impossible for an increase (appearance) to occur without a corresponding and related decrease (disappearance), just as it is impossible for a mountain (increase) to appear without the simultaneous appearance of a valley (decrease).  It is also impossible for a decrease to appear in one location without a corresponding increase in another.  (Buddhist thinkers call this the principle of dependent origination).

It is impossible demonstrate something arising out of nothing because to do so we would have to first create or demonstrate a field of nothingness.  Such a field would have no characteristics or features, margins, size, shape, or location.  Consequently, it could not be an object of perception.  Since it is impossible to see, hear, smell, taste, or touch nothing, it is also impossible to show some thing (mass or energy) arising out of nothing.

Further, any observation involves changes in the observer's perceptual apparatus, hence it is in principle impossible for for something to appear (be noticed) without the appearance of that thing causing changes in other things (at a minimum, the perceiver's sensory organs).

This leads to the most important point that the law of conservation of mass and energy is an essential foundation to scientific knowledge of phenomena.  If phenomena did not conform to the conservation law, no scientific knowledge of phenomena would be possible. If things popped into and out of existence at random, it would be impossible to account for or control changes in phenomena.  This law simply describes the basic, unalterable nature of phenomena that makes scientific knowledge and technological control of phenomena possible.

Now, the energy balance equation is nothing more than a specific restatement of the conservation law.

As a matter of scientific principle, if the energy balance law did not apply to phenomena, it would be impossible to track flows of energy and mass in the environment or body, because energy or mass could suddenly come into existence or disappear into nothingness at any point in time.  From this it would follow that it would be impossible to control the flow of energy and mass in the environment. 

Refutation of the energy balance law would require an experiment in which a change in body energy stores is produced without an equivalent change in difference between energy input and expenditure.  In other words,1) an experiment wherein people accumulate body energy stores while while energy intake is either equal to or less than energy expenditure; or 2) an experiment wherein people lose body energy stores while energy intake is either equal to or greater than expenditure.

For example, an experiment where people fast and yet either maintain or gain weight; or an experiment wherein people consume more calories than they expend, yet either maintain or lose weight. 

From this it follows that in claiming that the energy balance equation is a hypothesis, Taubes conceptually allies himself with breatharians who claim that people can maintain body weight and health without food intake.  Apparently, the editors of the British Medical Journal consider the reasoning processes of the breatharians worthy of scientific attention.  They are apparently more gullible than the producers of 60 Minutes who put the scam artist to the test.

Taubes seems to be suggesting on one hand that "maybe" fasting, undereating, or eating foods rich in carbohydrates activates hormones or "lipophilic adipose tissue" in such a way that people will gain weight despite low food energy intake.

On the other hand, Taubes appears to venture the hypothesis that "maybe" obese people can starve the "lipophilic adipose" and lose weight by consuming lots of fat and calories.  Strangely he seems to think that "lipophilic" i.e. fat (lipo-) loving (-philic) adipose doesn't love dietary fat. 

Makes perfect sense, right?

What a magical world he lives in.  Applying his reasoning to other phenomena, I venture the following hypotheses:

Maybe the best way to stay optimally hydrated is to limit all water intake (including food source water) as much as possible, and dehydration is caused by drinking water.

Maybe the best way to accumulate wealth is to spend every penny one earns, and the best way to go broke is to save more than you spend.

Sarcasm aside, in stating the energy balance equation, no scientist is hypothesizing that the “change in body energy stores” is “the difference between energy intake and energy expenditure.”   

On the contrary, we use this equation to guide investigation and control of changes in body mass.  If someone’s body mass goes up, we look for increases in energy intake, or decreases in energy expenditure.  If someone’s body mass goes down, we look for decreases in energy intake, or increases in energy expenditure.  If we want to reduce body mass, we reduce energy intake or increase energy expenditure; if we want to increase body mass, we increase energy intake or decrease energy expenditure. 

In other words, we use this equation the same way we use the second law of motion––F=ma–– to understand or control the motions and impacts of objects.  This equation tells us how to increase or decrease forces by manipulation of mass or acceleration, just as the energy balance equation tells us how to increase or decrease body mass by manipulating energy intake or expenditure.

Trivial Tautology?

Taubes contends that “the energy balance notion has an obvious flaw: it is tautological.  If we get fatter (more massive), we have to take in more calories than we expend––that’s what the laws of thermodynamics dictate––and so we must be overeating during this fattening process. But this tells us nothing about cause.”

In this statement, Taubes shifts from calling the energy balance equation a hypothesis to saying that it is dictated by the laws of thermodynamics, contradicting his own claim that it is a hypothesis.  But now he thinks he can dismiss it because it is a meaningless tautology.

So now we need to understand tautology. 

A tautology is a statement that is true under all circumstances by virtue of its logical structure.

Before going any further, I want to point out that Taubes calls energy balance both a hypothesis and a tautology, but it is impossible for any statement to be both a hypothesis and a tautology, because a hypothesis proposes a possibility, and may be refuted, but a tautology is true under any and all circumstances, so can never be refuted.

Anyone who calls the energy balance law both a hypothesis and a tautology reveals an incorrect understanding of both types of statements and a very poor grasp of fundamental principles of logic, epistemology, and science.  Anyone who allows someone else to publish a paper in BMJ with this fundamental contradiction is similarly lacking. 

Some frequently discussed examples of tautology are:

This mystery is unsolved.
A bachelor is an unmarried male.
Red is a color.
It is either raining outside, or not raining outside, right now.
I think, therefore I am.

Now, let’s take a look at these four examples, asking, are these all tautological for the same reason?  The answer is NO.

The first example–”This mystery is unsolved”–is called a rhetorical tautology. Since a mystery is by definition unsolved, the statement is true under all circumstances and provides no new information.

“A bachelor is an unmarried male” is tautological by definition.  We don’t need to refer to experience to confirm this statement, by which I mean that we don’t confirm it by examining unmarried males, in an attempt to confirm that every one of them is a bachelor.  This statement is a tautology because by convention, we assign the same meaning to the word “bachelor” as to “unmarried male.”  We could just as easily decide to henceforward use the word “pixidingdong” as synonymous with “unmarried male.”

“Red is a color” is tautological because red belongs to the class “colors.”  Therefore,  the statement is not informative because saying red is a color does not give new information about red.  Notice that this is different from “A bachelor is an unmarried male” because while ALL bachelors are unmarried males and vice versa, red is a color, but not all colors are red. 

“It is either raining or not raining outside right now” is true under all circumstances because it is a statement of jointly exhaustive and mutually exclusive alternatives.  The general form of such statements is "A or not A."

Finally we get to Descartes’s famous dictum “I think therefore I am.” This has also been called a tautology on the grounds that the statement “I think” is said to already include the statement “I am.”  In other words, it is claimed to be without information because if I say “I think” I am already saying “I am.”

However, people who make the claim that this statement provides no information seem to have missed something very important.  How does one know the meaning and relationship of the statements “I think” or “I am"?  Does one merely look it up in a dictionary?  Did you have to be taught that “I think” includes “I am” the way that you had to be taught that “bachelor” means “unmarried male,” or “color” includes “red” or “mystery” means “unsolved”?  Is “I think” arbitrarily related to “I am” as “bachelor” is to “unmarried male”?  Is “I think” a species of “I am” as “red” is of “color”?

It should be very clear that meanings of "I think" and "I am" are neither arbitrarily derived nor arbitrarily related like "bachelor" and "unmarried male."

Try as one may, it is impossible to give a meaningful lexical definition of “thinking” or “being.”  These concepts derive their meaning directly from our direct experience of being and thinking.  Moreover, one knows that “I think” includes “I am” not by mere analysis of terms, nor because someone told us so, but by direct experience.   

Further, Descartes was not a stupid man who spouted uninformative bullshit.  He did make some mistakes, but unlike those who attack his statement as a trivial tautology, he was astute enough to see that the statement “I think, therefore I am” conveys profoundly important information about the structure of experience and the relative ontological status of one’s own self in comparison to the objects one observes, as well as the vast difference in epistemological status between this statement and statements about the observed world, like "The sky is blue."  

Descartes saw that "I think therefore I am" conveys the important fact that one’s own existence is certain beyond doubt, because one’s existence is the necessary condition for one’s doubting (thinking); whereas the statement "The sky is blue" is not beyond doubt, and in fact is contingent upon a certain condition of one's eyes.  By the latter statement I simply mean that if we had eyes with some different conditions, the sky would not appear to us as what we now call blue. 

Hence, although it is in a sense correct to call “I think, therefore I am” an analytical truth or tautology, this statement is very, very different from “the mystery is unsolved,” “a bachelor is an unmarried male,” “red is a color,”   or “A or not A.”

I discuss this last example extensively because it shows that some so-called tautologies are not trivial statements, but in fact convey information about the fundamental structure of our experience.  

Now, as I stated above, the energy balance concept is actually a physical science equation. 

ΔEbm = Ei – Ee

If this is a tautology, then so also are other such equations, such as:

E = mc2

F = ma

In the case of “a bachelor is an unmarried male,” we arbitrarily establish an equivalence between the word “bachelor” and the status “unmarried male.”  But when Newton formulated the equation “force equals mass multiplied by the acceleration” he was not arbitrarily defining “force” as “mass x acceleration,” and Einstein did not define E as mc2 on a whim.  On the contrary these scientists discovered these equations only after very hard work attempting to understand the behavior of phenomena.

Further, neither F=ma nor E= mc2 is a statement of class inclusion like “red is a color.”  Nor do these equations state jointly exhaustive alternatives, like “it is either raining or not raining outside right now.” 

Someone might try to argue that in physics the word “force” has the same meaning as “mass x acceleration” and therefore that the equation F=ma is a tautology.  Let's accept this.  Would this deprive this equation of its immense scientific importance and power?   

In fact, each of these equations mathematically expresses the behavior of phenomena and enables us to understand and control the behavior of phenomena.
Source: Physics UMD

For example, F=ma states that the existence and magnitude of any force depends upon  i.e. arises from a mass and acceleration.  Knowledge of this tautology enables us to answer questions.

If I ask the question, “If I drop a feather and a boulder from the same height to the earth, why does the feather hardly disturb the  earth while the boulder leaves a crater?”  The second law of motion provides the answer that although both feather and boulder are subjected to the same acceleration, the boulder hits the earth with more force because it has a greater mass. 

If I ask the question, “How can I increase the safety of resistance exercise for the joints?”  the second law of motion provides the answer:  Reduce the forces to which you subject the joints by reducing the acceleration applied to the resistance.  In other words, gradually apply force to the resistance when starting movement, and at turnarounds in the range of motion, ease into and out of the ends of the range of motion, never yanking on the resistance or letting it drop.

In his BMJ article, Taubes wrote:

“If we get fatter (more massive), we have to take in more calories than we expend––that’s what the laws of thermodynamics dictate––and so we must be overeating during this fattening process. But this tells us nothing about cause.  Here’s the circular logic:

Why do we get fat? Because we overeat.

How do we know we’re overeating? Because we’re getting fatter.

Andy why are we getting fatter?  Because we’re overeating.

And so it goes, round and round.”

Is this circular reasoning?  No.  Circular reasoning occurs when someone makes an argument that includes the dubious conclusion as one of the premises.  The statement "We grow fat because we overeat" is not an argument, nor is it logically reducible to either "We grow fat because we grow fat" or "We overeat because we overeat."

To clarify, by Taubes's reasoning the statement "My car starts because I turned the ignition switch" is circular logic, and reducible to "My car starts because my car starts" or "I turned the ignition switch because I turned the ignition switch."  If he believed what he wrote, then he was at the time incapable of distinguishing a causal statement from circular reasoning.  This would make it difficult for him to pass a basic logic course.

Now, suppose you went to a physicist and said:

“If I want to reduce the forces acting on my knee joints, I have to either reduce my body mass or my acceleration––that’s what Newton’s second law states––and so I must be reducing my mass or my acceleration during this force-reduction process.  But this tells me nothing about cause.  This is the circular logic:

Why are my knees subject to high forces?  Because of high mass or acceleration.

How do I know mass or acceleration is high?  Because my knees are subject to high forces.

And why are my knees subject to high forces?  Because of high mass or acceleration.

And so it goes, round and round.” 

Would the physicist now throw up his hands and say “Oh my stars, you have just shown that F=ma is just a trivial tautological hypothesis and circular logic!”?  Emphatically not.  Instead, he might say “Idiot!  All you need to do is reduce your acceleration, more specifically you should decelerate as you come into contact with the earth.  For example, walk with gentle steps, don’t run or jump.  Or you could eat less and lose 40 pounds. What’s the matter with you?”

If you retorted with “But I want to know what will cause me to walk instead of running, or cause me to eat less and lose 10 pounds.  This equation doesn’t help me”  the physicist might wonder how anyone who appears to have control over his speech could not understand how to control his speed of locomotion or the trajectory of hand to mouth. 

Similar to F=ma and E= mc2, in the energy balance law,  we aren’t arbitrarily equating “change in body energy stores” as “the difference between energy intake and energy expenditure” in the way that “bachelor” is arbitrarily defined as “unmarried male.” 

Nor are we stating that “change in body energy stores” belongs to the class “the difference between energy intake and energy expenditure” as in the tautology “red is a color.” 

On the contrary, the energy balance equation expresses a natural law that describes the behavior of phenomena within a particular realm. Although it may be said to satisfy the criteria for a tautology because of the meanings of the terms, the meanings of the terms are not arbitrary but derived from and representative of a basic, unalterable feature of our experience.  Hence, it is both an analytical truth and a phenomenologically grounded truth, discovered only after extensive scientific study of phenomena, not arbitrarily created. One of my mentors, physicist and philosopher of science Ramakrishna Puligandla Ph.D. correctly classifies these statements as phenomenological-analytical truths.

Far from trivial and uninformative, Newton’s apparently tautological second law of motion tells us the necessary physical conditions for manifestation and alterations of physical forces, and opened up a whole world of physics and engineering that was unknown before Newton. 

Similarly, the energy balance law It tells us the necessary conditions for change in body energy stores:  a difference between energy intake and energy expenditure, and made it possible to discover the various factors that affect net energy intake and net energy expenditure.

Consequently, like all other scientific laws and equations, although the energy balance law appears analytically true or tautological, it is not trivial or uninformative, because it is grounded in the structure of our experience. 

Key Points

It is impossible for any statement to be both a hypothesis and a tautology.

The law of conservation of mass and energy is not a hypothesis but is true of any and all phenomena at all times and places because it is the very nature of phenomena to be dependent upon and derived from (i.e. transformations of) other phenomena.

The energy balance equation is a specialized statement of the law of conservation of mass and energy.

Not all tautologies are trivial and uninformative.  Modern science owes much of its power to the discovery of natural laws which can only be expressed in apparently tautological form.

One must understand the difference between a hypothesis and a tautology, and the differences between various types of tautologies especially in regard to their origins, in order to have an accurate understanding of the principles and practice of science.

Although Gary Taubes hoped to dismiss the energy balance law as trivial and uninformative by calling it both a hypothesis and a tautology, he only thereby revealed a lack of understanding of the terms he used and of the basic principles of natural sciences.

Friday, October 3, 2014

Cracking the Large Fluffy Myth

Dr. Greger discusses research casting doubt on the idea promoted by the egg industry that large fluffy LDL protects against atherosclerosis or coronary heart disease.  The studies he cites indicate that having large LDL particles predominating does not substantially reduce risk relative to having small LDL particles, but still increases risk relative to having low total LDL.[ 1, 2 ]

Mora et al studied women and reported "However, when small and large LDLNMR were examined in a model that included all 9 NMR-measured lipoprotein particle concentrations (data not shown), both large and small LDLNMR were significantly associated with CVD to a similar degree." [ 1] They also found that small dense HDL appeared to increase risk of CVD.

Otvos et al studied men and reported "Both large and small LDL subclass particle numbers were now strongly and independently predictive of CHD outcomes, both at baseline and during the trial. ORs for small and large LDL-P during the trial were 1.41 (95% CI, 1.14 to 1.73; P=0.001) and 1.34 (95% CI, 1.11 to 1.62; P=0.002), respectively." [2 ] In their population, small LDL increased risk by 41%, and large LDL by 34%; similar risk regardless of particle size (at any give total LDL concentration).  They found "Mean LDL and HDL particle sizes were not associated with CHD events."

Tuesday, September 2, 2014

Why Did I Get Fat on a Low-Fat, High-Carbohydrate Diet? Answered.

"A Call for a Low-Carb Diet that Embraces Fat" - Rebutted

Writing in the New York Times, Anahad O'Connor has made "A Call for a Low-Carb Diet that Embraces Fat."

He leads his article with the claim:
"People who avoid carbohydrates and eat more fat, even saturated fat, lose more body fat and have fewer cardiovascular risks than people who follow the low-fat diet that health authorities have favored for decades, a major new study shows."
He refers to a study by Bazzano et al, just published in the Annals of Internal Medicine:

Effects of Low-Carbohydrate and Low-Fat Diets: A Randomized Trial

I don't yet have access to the full text of this study, but I have found enough information about it in reports by media cheerleaders to cast doubt on O'Connor's claim.  

 Its a Matter of Perspective

According to O'Connor's report:
"It included a racially diverse group of 150 men and women — a rarity in clinical nutrition studies — who were assigned to follow diets for one year that limited either the amount of carbs or fat that they could eat, but not overall calories.

“'To my knowledge, this is one of the first long-term trials that’s given these diets without calorie restrictions,' said Dariush Mozaffarian, the dean of the Friedman School of Nutrition Science and Policy at Tufts University, who was not involved in the new study. “It shows that in a free-living setting, cutting your carbs helps you lose weight without focusing on calories. And that’s really important because someone can change what they eat more easily than trying to cut down on their calories.”
I find Mozaffarian's statement interesting.  According to Nancy Walsh of MedPageToday:
"At 12 months, individuals on a low-carbohydrate diet had lost 5.3 kg (11.7 lb), while those on a low-fat diet with similar caloric value had lost 1.8 kg (3.9 lb), for a mean difference of -3.5 kg, or 7.7 lb (95% CI minus 5.6-minus 1.4, P=0.002), according to Lydia Bazzano, MD, PhD, of Tulane University in New Orleans, and colleagues."
Since the subjects were advised only to limit either carbohydrate-rich foods or fat-rich foods, but not calories,  I can take Mozaffarian's words and replace "carbs" with "fat" and the statement will still be true:
This study shows that in a free-living setting, cutting your fat helps you lose weight without focusing on calories. And that’s really important because someone can change what they eat more easily than trying to cut down on their calories.
Source: ManaLeak

Math, Anyone?

Walsh states at least twice that kcaloric intakes between the two groups were "similar;" once in the passage quoted above – "those on a low-fat diet with similar caloric value"and in the following passage: 
"Throughout the study, physical activity and caloric intake were similar in the two groups -- the 12-month average caloric content of the low-carb and low-fat diets was 1,448 and 1,527 calories, respectively -- and approximately 80% of participants in both groups completed the yearlong trial."
I am embarrassed to say that I initially fell for her claim that the caloric intakes were "similar" between the groups while glossing over the 79 kcalorie dissimilarity between the groups. Usually I run the numbers but in this case, for about 5-10 minutes, I fell under the spell she cast.  But in perusing the comments on her report I found a comment by a physician who did not fall under the spell and his words woke me right up:

Actually, Dr. Ostrow made a little math mistake: a year has 365 days (not 356), and  79 x 365 = 28,835 (not 28,124).  Since 1 pound of body fat equals 3,500 kcal, the difference in kcalorie intake between the groups would account for as much as 8.2 pounds greater weight loss for the low-carbohydrate diet group.  So the small difference in kcaloric intake between the two groups fully accounts for the difference in body mass change.

I wonder why Walsh repeatedly called the kcaloric intakes "similar" when over a long term, like the year length of this study, a 79 kcalorie daily difference is very significant?  Did Bazzano et al. call these diets "similar in energy content"?  Did they do the math?

 It is well known that weight loss will reduce total and LDL cholesterol and triglycerides, and raise HDL levels, and that the degree of changes in these serum lipids is proportional to the amount of body fat lost.

This hardly justifies "A Call for Low Carb Diets."  This study did not demonstrate that a low-carbohydrate diet produces a better outcome than a low-fat diet.  It demonstrated that a 1,448 kcal diet produces greater weight loss and improvements in serum lipids than a 1,527 kcalorie diet.

These reported kcaloric intakes were lower than the 1800 kcal per day consumed by subjects in the Minnesota Starvation Experiment.  The blood lipids of the starvation subjects declined as well.
"You sure lost a lot of weight!" "Yeah, and my cholesterol went down too!"
Source: Minnesota Starvation Experiment, MNOpedia
So this new study essentially reports that starvation diets reduce body mass and blood lipids, regardless of composition, and moreso the greater the level of starvation.

This is not news. 
Who Prescribed the Protein-Deficient Diet?

O'Connor reports:
"While the low-fat group did lose weight, they appeared to lose more muscle than fat.

“'They actually lost lean muscle mass, which is a bad thing,'” Dr. Mozaffarian said. 'Your balance of lean mass versus fat mass is much more important than weight. And that’s a very important finding that shows why the low-carb, high-fat group did so metabolically well.'"
It has been well known for a long time (~30 years at least) that when people consume an energy- restricted diet, their protein requirements for preservation of lean body mass increase.  Since the LC group in this study, according to O'Connor, "were told to eat mostly protein and fat," it is most likely that they were more successful than the LF dieters at preserving lean mass because they consumed adequate protein.  The LF dieters probably consumed too little protein due to their low caloric intake and avoidance of commonly consumed protein-rich foods.

A meta-analysis of twenty-four trials that included 1063 individuals suggested that when people eat a low-fat diet for weight loss, they will preserve more lean mass, lose more fat mass, and achieve lower triglyceride levels with a higher (25-35% of energy) protein intake as opposed to a standard (i.e. 12-18% of energy) intake.  The required higher protein intake translates to more than 1.0 g per kg per day, or roughly more than 25% more protein than so-called standard diets. 

A 1527 kcal diet (as consumed by the LF dieters in this study) with ~15% of energy from protein provides only 57 g protein.  On the basis of the research just noted, this would be adequate only for someone who weighed only 57 kg (125 pounds) at the start of the study.  This most likely would not be an individual needing to lose body weight and body fat.

A low-fat plant-based does not have to be low in protein.  Tracy weighs only 45 kg (100 pounds) and frequently consumes 70-80 g protein daily (1.6 g/kg) while still having a low fat intake (less than 20% of energy).  She posts examples here.
Beans: The Really Lean Proteins
Source:  Marilu Henner

So who was (ir-) responsible for prescribing the protein-deficient diet to the LF diet group in this study, in ignorance of the well-established increased protein requirements during low caloric intake?

Was this study deliberately or unconsciously rigged to show that a LC diet is better at preserving lean mass than a LF diet?
The Peril of Percentages

As for O'Connor's lead claim:
"People who avoid carbohydrates and eat more fat, even saturated fat, lose more body fat and have fewer cardiovascular risks than people who follow the low-fat diet that health authorities have favored for decades, a major new study shows."
He conveniently omitted from this lead paragraph the fact that these outcomes were dependent on a very low energy intake of 1,448 kcal per day.

In addition, O'Connor states:
"Over all, they [the LC diet group] took in a little more than 13 percent of their daily calories from saturated fat, more than double the 5 to 6 percent limit recommended by the American Heart Association. The majority of their fat intake, however, was unsaturated fats."
It seems O'Connor overlooked the fact that percentages do not identify absolute amounts. 

Let me clarify: 13% of 1,448 = 188.  Since fats yield 9 kcal per gram, this means the LC group averaged about 20 g of saturated fats daily.  According to the CDC,  the mean daily saturated fat intake for Americans in the years 1999-2000 was 11% of total kcal intake, and the mean total kcal intake was 2,154 (males and females combined).  Thus, typical non-dieting Americans consume 236 kcal or 26 g saturated fats daily.  Thus, this LC diet very likely contained less – about 23% less – saturated fat than found in the typical American diet, despite having a higher percentage of total calories as saturated fat.

Now consider that the participants in this study were overweight or obese when beginning the study.  Maintenance of an overweight condition generally requires a kcalorie intake larger than 2,154 kcalories daily.  I consume 2500-3000 kcal daily and am quite lean at ~155 pounds.  Tracy is lean at ~100 pounds and consumes 1600-1900 daily.  The subjects in this study most likely consumed 2500 or more kcal daily before starting the study diets.  If they consumed only the typical 11% of energy from saturated fat they would have been getting 30 g saturated fat daily.  The 1,448 kcal LC diet provided one-third less saturated fat daily as compared to a 2500 kcal, 11% saturated fat diet.  

The study probably does not support O'Connor's lead claim that eating more fat produced the results in this study, because the participants probably did not eat more fat; probably they ate less than they did prior to the trial!

At the very least, this study provides no evidence that increasing saturated fat intake is beneficial to weight loss or cardiovascular health, because participants probably did not increase absolute intake of saturated fats. Probably this study only further confirms that decreasing saturated fat intake from typical U.S. levels or levels consumed by overweight individuals reduces cardiovascular disease risk factors.  It falls far short of refuting the lipid hypothesis.

Output Depends on Input

By starting his lead claim with "People who..." rather than "Overweight individuals with high blood lipids...." O'Connor seems to suggest that this study suggests that anyone who eats more bacon and other high-fat animal foods and less carbohydrate-rich whole foods will, over the long term, improve their cardiovascular risk.  A study published by Smith et al in the International Journal of Exercise Science casts doubt on this wishful thinking.
You No Like Paleo Diet? I Teach You Lesson!
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In this study, healthy, active subjects with total cholesterol levels under 200 mg/dL (males, 172; females, 165) and fair LDL levels ( males, 106 mg/dL; females 77) were told to eat as much as they wanted of "Paleo DietTM" approved foods:
"Subjects were advised to increase their consumption of lean meat, fish, eggs, nuts, fruit, and vegetables and were instructed to strictly avoid all grains, dairy products, and legumes. All modern, processed foods including any form of processed sugar, soft drinks, and coffees were also excluded from the diets of the subjects."
The subjects did not restrict food intake, only the types of foods consumed.  In addition, they participated in a "CrossFit-based circuit-training program."

Subjects lost body weight and body fat, but said "farewell" to healthy blood lipids.  The participants overall had increases in non-HDL, LDL, Total Cholesterol (TC), and the TC/HDL ratio, with no significant change in HDL.  More importantly, those who had the healthiest lipid levels at the start of the study had the most deleterious changes.  The authors commented:
"The Law of Initial Values might explain why these deleterious effects were so pronounced in subjects with the healthiest blood lipid profiles. Subjects with optimal initial blood lipids were unable to maintain their ideal blood lipid values after adhering to the Paleo diet for 10 weeks, whereas a similar effect would not likely be seen in subjects with poor initial blood lipid values."
In other words, if you want to rig a study to show that eating lots of meat and fat improves your blood lipids, just make sure to use a study population that has really high blood lipids to start. 
"Simply limiting food sources to the list of Paleo-approved foods could effectively improve the diet of very unhealthy populations, but the results of our study indicate that it may be difficult to maintain an ideal blood lipid profile while adhering to the commonly followed Paleo guidelines used in this intervention." 
Smith et al. point out that prior to their study, other projects that claimed to show positive results of Paleo diets put restrictions on specific "Paleo" foods, and/or used subjects who were overweight, sedentary, or coronary heart disease or diabetes patients.  

This "Paleo Diet" intervention with healthy subjects shows clearly that O'Connor is not justified in drawing from the results of this small, poorly designed study by Bazzano et al. the suggestion that healthy people will reduce their cardiovascular risk by going on low-carbohydrate, high-fat animal-based diets.  

All in all, the reports by O'Connor and Walsh strike me as great examples of cheerleading supposedly good news about bad habits, presented by reporters sorely lacking adequate knowledge of the subject area as well as the critical scientific thinking skills needed to ask the right questions.  

Friday, August 29, 2014

Friday, August 15, 2014

The Truth About The Mediterranean Diet

The Cretan diet that gave rise to the interest in the so-called Mediterranean diet was not high in fat, fish, feta, or Greek yogurt as advertised or implied by advertisers. It was high in bread, beans, potatoes, vegetables, and fruits and for adult men derived only ~7 percent of energy from all animal products. 

Men in the general Mediterranean consumed almost twice as much fish as the men in Crete but had a coronary heart disease mortality rate 20 times higher than Cretan men.  Less than 4% of the Cretan men's diet consisted of fish.  That data does not provide any support for the idea that fish consumption was responsible in any degree for the very low coronary heart disease mortality rate in Crete. 

Meanwhile, men in Crete consumed almost 4 times as much bread (and therefore, wheat) as men in the U.S. cohort of the Seven Countries study; and men in the U.S. consumed 4 times as much meat, fish, eggs, and dairy products than men in Crete. Yet the men in the U.S. had a heart disease death rate about 57 times that of the men in Crete.  This data does not support claims that wheat causes heart disease (it was a large part of the protective Cretan diet) nor claims that eating more low-carbohydrate animal products protects against heart disease.  

Cretans did not consume large amounts of feta cheese or "Greek yoghurt" either.  Only about 3% of their calories came from dairy products.  That amounts to about one-half cup of yoghurt or milk, or about one-half ounce of cheese, daily, for a man consuming 2500 kcal daily. 

In addition, the Cretans who had a low risk of heart disease did not consume large amounts of olive oil nor a diet providing 40% of energy as fat as commonly claimed.  In fact, a large portion of Cretans followed Greek Orthodox fasting rituals which prescribed avoidance of olive oil on fasting days amounting to at least half the days of the year (180 to 200 days). 

The commercialized mythical Mediterranean diet rich in olive oil, feta cheese, yoghurt and fish crosses the general Mediterranean diet and the Western diet, both of which supported high rates of cardiovascular disease – 20 to 57 time that of Cretan men – when Cretan men had the lowest recorded rate.  The lowest rate of heart disease death was found among the men who ate the least animal products and got 93% of their calories from a primarily whole foods plant based diet with small amounts of added olive oil.