The 2012 Arch Intern Med red meat-mortality study: The “protective” effect of smoking

In a previous post () I used WarpPLS () to analyze the model below, using data reported in a recent study looking at the relationship between red meat consumption and mortality. The model below shows the different paths through which smoking influences mortality, highlighted in red. The study was not about smoking, but data was collected on that variable; hence this post.

When one builds a model like the one above, and tests it with empirical data, the person does something similar to what a physicist would do. The model is a graphical representation of a complex equation, which embodies the beliefs of the modeler. WarpPLS builds the complex equation automatically for the user, who would otherwise have to write it down using mathematical symbols.

The results yielded by the complex equation, partly in the form of coefficients of association for direct relationships (the betas next to the arrows), have a meaning. Some may look odd, and require novel interpretations, much in the same way that odd results from an equation describing planetary motions may have led to the development of the theory of black holes.

Nothing is actually "proven" by the results. They are part of the long and painstaking process we call "research". To advance new knowledge, one needs a lot more than a single study. Darwin's theory of evolution is still being tested. Based on various tests and partial refutations, it has itself evolved a great deal since its original formulation.

One set of results that are generated based on the model above by WarpPLS, in addition to coefficients for direct relationships, are coefficients of association called "total effects". They aggregate all of the effects, via multiple paths, between each pair of variables. Below is a table of total effects, with the total effects of smoking on diabetes incidence and overall mortality highlighted in red.

As you can see, the total effects of smoking on diabetes incidence and overall mortality are negative, but small enough to be considered insignificant. This is interesting, because smoking is definitely not health-promoting. Among hunter-gatherers, who often smoke tobacco, it increases the incidence of various types of cancer (). And it may be at the source of many of the health problems suggested by analyses on the China Study II data ().

So what are these results telling us? They tell us that smoking has an intermediate protective effect, very likely associated with its anorexic effect. Smoking is an appetite suppressor. Its total effect on food intake is negative, and strong. As we can see from the table of total effects, just below the two numbers highlighted in red, the total effect of smoking on food intake is -0.356.

Still, it looks like smoking is nearly as bad as overeating to the point of becoming obese (), in terms of its overall effect on health. Otherwise we would see a positive total effect on overall mortality of comparable strength to the negative total effect on food intake.

Smoking may make one eat less, but it ends up hastening one’s demise through different paths.

Does pork consumption cause cirrhosis? Perhaps, if people become obese from eating pork

The idea that pork consumption may cause cirrhosis has been around for a while. A fairly widely cited 1985 study by Nanji and French () provides one of the strongest indictments of pork: “In countries with low alcohol consumption, no correlation was obtained between alcohol consumption and cirrhosis. However, a significant correlation was obtained between cirrhosis and pork.”

Recently Paul Jaminet wrote a blog post on the possible link between pork consumption and cirrhosis (). Paul should be commended for bringing this topic to the fore, as the implications are far-reaching and very serious. One of the key studies mentioned in Paul’s post is a 2009 article by Bridges (), from which the graphs below were taken.

The graphs above show a correlation between cirrhosis and alcohol consumption of 0.71, and a correlation between cirrhosis and pork consumption of 0.83. That is, the correlation between cirrhosis and pork consumption is the stronger of the two! Combining this with the Nanji and French study, we have evidence that: (a) in countries with low alcohol consumption we can find a significant correlation between cirrhosis and pork consumption; and (b) in countries where both alcohol and pork are consumed, pork consumption has the strongest correlation with cirrhosis.

Do we need anything else to ban pork from our diets? Yes, we do, as there is more to this story.

Clearly alcohol and pork consumption are correlated as well, as we can see from the graphs above. That is, countries where alcohol is consumed more heavily also tend to have higher levels of pork consumption. If alcohol and pork consumption are correlated, then a multivariate analysis of their effects should be conducted, as one of the hypothesized effects (of alcohol or pork) on cirrhosis may even disappear after controlling for the other effect.

I created a dataset, as best as I could, based on the graphs from the Bridges article. (I could not get the data online.) I then entered it into WarpPLS (). I wanted to run a moderating effect analysis, which is a form of nonlinear multivariate analysis. This is important, because the association between alcohol consumption and disease in general is well known to be nonlinear.

In fact, the relationship between alcohol consumption and disease is often used as a classic example of hormesis (), and its characteristic J-curve shape. Since correlation is a measure of linear association, the lower correlation between alcohol consumption and cirrhosis, when compared with pork consumption, may be just a “mirage of linearity”. In multivariate analyses, this mirage of linearity may lead to what are known as type I and II errors, at the same time ().

I should note that the Bridges study did something akin to a moderating effect analysis; through an analysis of the interaction between alcohol and pork consumption. However, in that analysis the values of the variables that were multiplied to create a “dummy” interaction variable were on their original scales, which can be a major source of bias. A more advisable way to conduct an interaction effect analysis is to first make the variables dimensionless, by standardizing them, and then creating a dummy interaction variable as a product of the two variables. That is what WarpPLS does for moderating effects’ estimation.

One more detour, leading to an important implication, and then we will get to the results. In a 1988 article, Jeanneret and colleagues show evidence of a strong and possibly causal association between alcohol consumption and protein-rich diets (). One possible implication of this is that in countries where pork is a dietary staple, like Denmark and Germany, alcohol consumption should be strongly and causally associated with pork consumption. (I guess Anthony Bordain would agree with this eh?)

Below are the results of a multivariate analysis on a model that incorporates the above implication, by including a link between alcohol and pork consumption. The model also explores the role of pork consumption as a moderator of the relationship between alcohol and cirrhosis, as well as the direct effect of pork consumption on cirrhosis. Finally, the total effects of alcohol and pork consumption on cirrhosis are also investigated; they are shown on the left.

The total effects are both statistically significant, with the total effect of alcohol consumption being 94 percent stronger than the total effect of pork consumption on cirrhosis. Looking at the model, alcohol consumption is strongly associated with pork consumption (which is consistent with Jeanneret and colleagues’s study). Alcohol consumption is also strongly associated with cirrhosis, through a direct effect; much more so than pork. Finally, pork consumption seems to strengthen the relationship between alcohol consumption and cirrhosis (the moderating effect).

As we can see the relationship between pork consumption and cirrhosis is still there, in moderating and direct effects, even though it seems to be a lot weaker than that between alcohol consumption and cirrhosis. Why does pork seem to influence cirrhosis at all in this dataset?

Well, there is another factor that is strongly associated with cirrhosis, and that is obesity (). In fact, obesity is associated with just about any major disease, including various types of cancer ().

And in countries where pork is a dietary staple, isn’t it reasonable to assume that pork consumption will play a role in obesity? Often folks who consume a lot of addictive industrial foods (e.g., bread, candy, regular sodas) also eat plenty of foods with saturated fat; and the latter end up showing up in disease statistics, misleadingly supporting the lipid hypothesis. The phenomenon involving pork and cirrhosis may well be similar.

But you may find the above results and argument not convincing enough. Maybe you want to see some evidence that pork is actually good for one’s health. The results above suggest that it may not be bad at all, if you buy into the obesity angle, but not that it can be good.

So I downloaded the most recent data from Nationmaster.com () on the following variables: pork consumption, alcohol consumption, and life expectancy. The list of countries was a bit larger than and different from that in the Bridges study; the following countries were included: Australia, Brazil, Canada, China, Denmark, France, Germany, Hong Kong, Hungary, Japan, Mexico, Poland, Russia, Singapore, Spain, Sweden, United Kingdom, and United States. Below are the results of a simple multivariate analysis with WarpPLS.

As with the Bridges dataset, there is a strong multivariate association between alcohol and pork consumption (0.43). The multivariate association between alcohol consumption and life expectancy is negative (-0.14). The multivariate association between pork consumption and life expectancy is positive (0.36). Neither association is statistically significant, although the association involving pork consumption gets close to significance with a P=0.11 (a confidence level of 89 percent; calculated through jackknifing, a nonparametric technique). The graphs show the plots for the associations and the best-fitting lines; the blue dashed arrows indicate the multivariate associations to which the graphs refer. So, in this second dataset from Nationmaster.com, the more pork is consumed in a country, the longer is the life expectancy in that country.

In other words, for each 1 standard deviation variation in pork consumption, there is a 0.36 standard deviation variation in life expectancy, after we control for alcohol consumption. The standard deviation for pork consumption is 36.281 lbs/person/year, or 45.087 g/person/day; for life expectancy, it is 4.677 years. Working the numbers a bit more, the results above suggest that each extra gram of pork consumed per person per day is associated with approximately 13 additional days of overall life expectancy in a country! This is calculated as: 4.677/45.087*0.36*365 = 13.630.

Does this prove that eating pork will make you live longer? No single study will “prove” something like that. Pork consumption is also likely a marker for wealth in a country; and wealth is strongly and positively associated with life expectancy at the country level. Moreover, when you aggregate dietary and disease incidence data by country, often the statistical effects are caused by those people in the dietary extremes (e.g., alcohol abuse, not moderate consumption). Finally, if people avoid death from certain diseases, they will die in higher quantities from other diseases, which may bias statistical results toward what may look like a higher incidence of those other diseases.

What the results summarized in this post do suggest is that pork consumption may not be a problem at all, unless you become obese from eating it. How do you get obese from eating pork? Eating it together with industrial foods that are addictive would probably help.

All diets succeed at first, and eventually fail

It is not very hard to find studies supporting one diet or another. Gardner and colleagues, for example, conducted a study in which the Atkins diet came out on top when compared with the Zone, Ornish, and LEARN diets (). In Dansinger and colleagues’ study (), on the other hand, following the Atkins diet led to relatively poor results compared with the Ornish, Weight Watchers, and Zone diets.

Often the diets compared have different macronutrient ratios, which end up becoming the focus of the comparison. Many consider Sacks and colleagues’ conclusion, based on yet another diet comparison study (), to be the most consistent with the body of evidence as a whole: “Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize”.

I think there is a different conclusion that is even more consistent with the body of evidence out there. This conclusion is highlighted by the findings of almost all diet studies where participants were followed for more than 1 year. But the relevant findings are typically buried in the papers that summarize the studies, and are almost never mentioned in the abstracts. Take for example the study by Toubro and Astrup (); Figure 3 below is used by the authors to highlight the study’s main reported finding: “Ad lib, low fat, high carbohydrate diet was superior to fixed energy intake for maintaining weight after a major weight loss”.

But what does the figure above really tell us? It tells us, quite simply, that both diets succeeded at first, and then eventually failed. One failed slightly less miserably than the other, in this study. The percentage of subjects that maintained a weight loss above 25 kg (about 55 lbs) approached zero after 12 months, in both diets. This leads us to the conclusion below, which is always missing in diet studies even when the evidence is staring back at us. This is arguably the conclusion that is the most consistent with the body of evidence out there.

All diets succeed at first, and eventually fail.

In using the terms “succeed” and “fail” I am referring to the diets’ effects on the majority of the participants. This is in fact better demonstrated by the figure below, from the same study by Toubro and Astrup; it is labeled as Figure 2 there. Most of the participants at a certain weight, lose a lot of weight within a period of 1 year or so, and after 2 years (see the two points at the far right) are at the same original weight again. What is the average time to regain back the weight? From what I’ve seen in the literature, all the weight and some tends to be regained after 2-3 years.

The regained weight is not at all lean body mass. It is primarily, if not entirely, body fat. In fact, many studies suggest that those who diet tend to have a higher percentage of body fat when they regain their original weight; proportionally to how fast they regain the weight lost. Since the extra body fat tends to cause additional problems, which are compounded by the dieting process’ toll on the body, those dieters would have been slightly better off not having dieted in the first place.

Guyenet and Schwartz have recently authored an article that summarizes quite nicely what tends to happen with both obese and lean dieters (). Take a look at Figure 2 of the article below. The obese need to lose body fat to improve health markers, and avoid a number of downstream complications, such as type 2 diabetes and cancer (). Yet, with very few exceptions, the obese (and even the overweight) remain obese (or overweight) after dieting; regardless of the diet.

So what about those exceptions, what do they do to lose significant amounts of body fat and keep it off? Well, I rarely use myself as an example for anything in this blog, but this is something with which I unfortunately/fortunately have personal experience. I was obese, lost about 60 lbs of weight, and kept it off for quite a while already (). Like most of the formerly obese, I can very easily gain body fat back.

But I don’t seem to be gaining back the formerly lost body fat, and the reason is consistent with some of the studies based on data from the National Weight Control Registry, which stores information about adults who lost 30 lbs or more of weight and kept it off for at least 1 year (). I systematically measure my weight, body fat percentage, and a number of other variables; probably even more than the average National Weight Control Registry member. Based on those measurements, I try to understand how my body responds in the short and long term to stimuli such as different exercise, types of food, calorie restriction, sleep patterns etc.

And I act accordingly to keep any body fat gain from happening; by, for example, varying calorie intake, increasing exercise intensity, varying the types of food I eat etc. With a few exceptions (e.g., avoiding industrial seed oils), there is no generic formula. Customization based on individual responses and cyclical patterns seems to be a must.

Looking back, it was relatively easy for me to lose all that fat. This is consistent with the studies summarized in this post; all diets that rely on caloric reduction work marvelously at first for most people. The really difficult part is to keep the body fat off. I believe that this is especially true as the initial years go by, and becomes easier after that. This has something to do with initial inertia, which I will discuss soon in a post on metabolic rates and their relationship with overall body mass.

For people living in the wild, I can see one thing working in their favor. And that is not regular starvation; sapiens is too smart for that. It is laziness. Hunger has to reach a certain threshold for people to want to do some work to get their food; this acts as a natural body composition regulator, something that I intend to discuss in one of my next posts. It seems that people almost never become obese in the wild, without access to industrial foods.

As for living in the wild, in spite of the romantic portrayals of it, the experience is not as appealing after you really try it. The book Yanomamo: The Fierce People () is a solid, if not somewhat shocking, reminder of that. I had the opportunity to meet and talk at length with its author, the great anthropologist Nap Chagnon, at one of the Human Behavior and Evolution Society conferences. The man is a real-life Indiana Jones ().

In the formerly obese, the body seems to resort to “guerrilla warfare”, employing all kinds of physiological and psychological mechanisms, some more subtle than others, to make sure that the lost fat is recovered. Why? I have some ideas, which I have discussed indirectly in posts throughout this blog, but I still need to understand the whole process a bit better. My ideas build on the notion of compensatory adaptation ().

You might have heard some very smart people say that you do not need to measure anything to lose body fat and keep it off. Many of those people have never been obese. Those who have been obese often had not cleared the 2-3 year “danger zone” by the time they made those statements.

There are many obese or overweight public figures (TV show hosts, actors, even health bloggers) who embark on a diet and lose a dramatic amount of body fat. They talk and/or write for a year or so about their success, and then either “disappear” or start complaining about health issues. Those health issues are often part of the “guerrilla warfare” I mentioned above.

A few persistent public figures will gain the fat back, in part or fully, and do the process all over again. It makes for interesting drama, and at least keeps those folks in the limelight.

Sometimes You Just Need a Pacer

I am a Pacer!!!

IF YOU LIKE MY BLOG…DONATE A PROTEIN SHAKE TODAY!

I love this title…created by my fabulous client Jennifer.  So many things come to mind when I think about Jennifer…fighter, athlete, determined, accomplished, motivational, inspirational, and a strong woman who has beat cancer and celebrated 5 years cancer free this year.  Jennifer contacted me to be her accountability coach and help her get back on track with her overall health program and let me tell you…I was over the top honored to accept the role.  She was a woman of my peers being a registered dietitian and working in the fitness industry herself for many years.  I was able to share my Stay Healthy Food Guide with her which she was very impressed by the simplicity of the presentation…this was a fabulous compliment for me coming from Jennifer. Let me tell you, Jennifer and I made a good team armed with the best of the best nutritional knowledge and information which was used to get her caloric intake back on track, and to gradually boost her metabolism into letting go of pounds that had accumulated over the years battling the preventative cancer medications that she had no control over. We worked together to create a fine balance of the nutrition that was needed to sustain the demands of her activity.  

 I was so excited every time Jennifer contacted me to share that she finished a walk. This is BIG stuff and each day seemed to progress in a positive energy direction.  I learned so much working with Jennifer and what she has gone through as a cancer survivor, the medications involved, the negative impact on the body and really….how it makes a person feel…like an out of body experience…this is my body but it does not do what I want it to.  The energy levels can be completely depleted and each day a guessing game of…will I be in bed today…or YEAH…I have energy for my walk. This type of up down roller coaster ride becomes a cycle of frustration for many and especially extreme athletes such as Jennifer.   I admire Jennifer for all her accomplishments and am so proud to have been and continue to be a part of her journey of healing through cancer.   

Jennifer celebrates her 60^th birthday tomorrow and so much more…Jennifer has reached and exceeded her fitness goals AND during the continuance of her medications…we both are celebrating this victory together BIG TIME!!!  Jennifer continues her walk/jogs, eating healthy, involvement in running events and health conferences, and supports events for the fight against breast cancer.  She is one busy, beautiful lady who is a walking example that overcoming obstacles are things that indeed make us stronger.  Jennifer lives the Stay Healthy life every day and is a role model for all people…as her Pacer…I am very MOTIVATED…Trainer Pride and Hugs…HAPPY 60^TH BIRTHDAY Jennifer!!!

My Email Response to Jennifer (you will understand why I posted this here after reading her story):

Hi Jennifer,

First…let me congratulate you on all your successes, and the Biggest Win…Surviving Cancer.  Life takes us through journeys we do not always understand and fighters we must be to continue to be the BEST we can with the limitations handed to us.  I again applaud your determination & motivation to do just that.  I also understand the frustrations of not being or feeling “who you once where” as I also suffered an injury in 2008 and it strips the very soul from an athlete.  Most important however, is taking what seems to be such an unfair journey and becoming even stronger, better, & wiser from the experience.  Acceptance of the NEW athlete that you are and will always be.  Does it take work and perseverance…a BIG YES…but I am reading that you have an inner strength that will carry you through.  The beautiful thing about our bodies is that we can work them in ways that are not as demanding, get fabulous results, with reduced risk of the negative side effects that always seem to rear their ugly heads if “old workout” philosophies are implemented.  A balance needs to be created that enables you to feel accomplished with your fitness, but at the same time preserves the quality of your life. I would love to meet with you for a consultation and YES…that is the first step when selecting the BEST fitness expert for you.  Thank you for sharing your story, getting in touch, and I look forward to hearing from you.

Jennifer last month at a Health Conference

Jennifer Today!

Making Strides Against Breast Cancer 2011

Sometimes You Just Need a Pacer

Here’s my story. It made all the difference in the world to have Darla by my side!

I am a registered dietitian, an aerobics instructor, and a marathon runner. I have had an active and healthy lifestyle for decades.

I am also a breast cancer survivor of 5 years and am currently finishing up a five year course of therapy which helps to prevent recurrence. One of the major side effects of this medicine for me has been fatigue. Enough fatigue that I had to stop running. Enough fatigue that I have spent a LOT of time resting on the couch.

Jennifer Persevering

Over the last five years, I have watched my formerly strong and active self become soft and tired. What’s more, I have watched my cholesterol increase to an unhealthy level – first time I ever had to worry about such a thing. 

I certainly did not have surgery, chemotherapy, and radiation, just to die of a heart attack! 

And, in spite of my training and lifestyle, I could not seem to help myself.

In April 2011, I went on line to research personal trainers in the Sacramento area. You all know how Google works, what comes up is what comes up, and that evening, Darla was the only trainer that popped up on the screen.

This is the message I sent to her….

Hi Darla

I found your Web site by chance through Google; I am not a referral.

I was an aerobics instructor when aerobics first came on the scene in the early 80's and taught aerobics for about 15 years.

I have also been a runner since 1983 - my last marathon was in 2000 and my last half marathon was in October 2008.

I am a registered dietitian. I retired from the California Department of Education in health education in 2009.

I will be 60 years old in October. I am a breast cancer survivor, beginning my last year of a five-year follow up hormonal treatment.

The major side effect of my follow-up treatment for cancer is fatigue. Each year that passes I have become more tired.  I have to be fairly careful about how much I work out or I have to spend the next day or so resting on the couch. I have learned the hard way that I can no longer "muscle" my way through a workout - mind over matter is not an option these days.  It is very frustrating, but it is what it is.

The other side effect is losing muscle and gaining fat. Although I weigh approximately as much as I did when I was diagnosed in 2006, my body composition is decidedly different. I was running about 25 - 30 miles a week at the time of diagnosis.  Now I can amble (17 minute miles) about 15 - 18 miles a week. What's more, if I try to cut calories much below 1800 calories a day (and I have tried), my fatigue increases and I become a screaming maniac. : - ) and, a lower calorie intake seems not to make a bit of difference to the amount I weigh.

Where do you come in?

I noticed that one of your services is Limited Physical/Injury. Believe me, it is not a lack of motivation or self discipline that is keeping me from being as active as I want to be, but I think I might find it helpful to work with someone to help me do the best I CAN do, whatever it may be.

I'm told that when I stop taking the medication, I still start feeling more like my "old" self again - be able to get out of first gear. For my last year on the medication, I would like to be in the best place I can be, so when I get off the medication, I have the most momentum possible.

What I think would be useful would be a consultation and, more importantly, follow up appointments at least once a month maybe?

What do you think?

Darla sent a loving, supportive e-mail back, and we began our journey together! My focus was always to get healthier – not simply to lose weight or get stronger.

I really appreciated Darla’s Stay Healthy Fitness Food Choice Eating Guide, which we discussed at my initial assessment. I could see that this simple plan focused on getting the very best nutrition. As a dietitian, I am often skeptical about food plans, but I was happy to see that this plan was based on current research.  In fact, I suggested that Darla should publish this plan in a book!

Even with my background in healthy eating, Darla’s eating plan helped me focus my food choices.  Because my calorie intake was lower than I was used to, I needed to get the best nutrition out of each and every little calorie.

My sustained work with Darla was more her supporting me with visits every two weeks, rather than her educating me. I kept a food diary (and I do to this day – every day) and she reviewed my daily intake.  There was not much emphasis put on building muscles or increasing aerobic capacity, because that was just not possible. Instead, bi-weekly monitoring of my activity simply helped me refine and improve what I was able to do – walk.

Fast forward six months.  Gradually, very gradually, I began to lose some weight. Because I was accountable to Darla through my food records, I focused on eating the very best I could, and remarkably, I was able to lower my calorie level without the physical meltdowns I had experienced on my own.

Gradually, slowly, I began to add a few more minutes of walking to my daily walk and pick up the pace a bit. The overall fatigue has not gone away, but I made activity a priority to the extent that I gave up some of my volunteer activities so that I would have energy to walk.

Now I am 30+ pounds lighter and my recent cholesterol measurement showed a 70 mg drop! I couldn’t ask for a better result!!

Right now, I have decreased my visits to Darla to once a month. I have developed good habits and I do not need the bi-weekly accountability check. For the future, Darla and I are looking forward to the time when I’m off the medication and the side effects have been minimized. At that time, we will start on some minimal strength work – while the weight I lost was mostly fat, it turns out I have lost serious muscle in the past five years.

For me, it was all about Darla being my “pacer.” Pacer is a word that occurs in the world of running. When you are running in a long event – like the marathon – you often ask someone to help you out as a “pacer.” Near the end of the run, your pacer joins you fresh as a daisy while you are ready to curl up in a ball by the curb. When I ran my marathons and my pacer joined me at mile 20, I always felt that I could now stop thinking and just put one foot ahead of the other. The important decisions would now be made by my pacer.

This is exactly how it worked for Darla and me. Darla took over the thinking and I just did what I was supposed to, until I could do it on my own.  Success!!

Sometimes you just need a pacer.

Jennifer Before                                                                         Jennifer Today

4-26-11, 157lbs                                                       Follow-up 9-13-11, 130lbs

BMI 25.5, BF 26.7%                                          BMI:21, BF 21.1%, Lost 10 more lbs

Jennifer continues to maintain herself through Stay Healthy nutrition, walks, walk jogs on her great days and I look forward to our... to be continued..  journey together as we transition to the next level of health & fitness goals...never a destination, but always a journey. 

  Congrats Jennifer...You are one FABULOUS WOMAN!!! 

IF YOU ENJOYED MY BLOG, LIKE IT, LEAVE A COMMENT AND IF INSPIRED, DONATE A SHAKE TODAY! Pink to represent my Supporting the fight Against Breast Cancer!

Stay Healthy!