A Putative Contributor

To catch up, please glance back at “Obesity Villains Reconsidered” and/or “Obesity Villains Exonerated.” These posts are based on a paper that cast doubt on or debunked some commonly held beliefs about the causes of obesity and supported others.

Either way, it encompassed some interesting material and provided a starting place to reassess various bits of received wisdom, because…

[…] scientists widely and readily acknowledge that multiple factors contribute to obesity including but not necessarily limited to genetic, dietary, economic, psychosocial, reproductive, and pharmacologic factors.

Among other ideas, the authors reconsidered the notion of the heavily criticized institution known as the “built environment.” In one case, they found a study that examined two racially same but economically different neighborhoods, and concluded that “levels of leisure walking and physical activity were not higher, and rates of obesity were not lower in the non-poor neighborhood with better maintenance, more sidewalks and recreational facilities.”

In another upset, the authors discovered that although high fructose corn syrup has been enthusiastically demonized, an American Medical Association position paper said “it appears unlikely that HFCS contributes more to obesity or other conditions than sucrose.” Similarly, although anti-obesity warriors hate vending machines, and devote a lot of energy to lobbying against their presence in schools, the actual evidence against the machines as obesity villains is underwhelming:

Our point is merely that we do not have conclusive evidence that the big two or their individual elements are the preeminent contributors to obesity. Despite the lack of solid evidence that clearly demonstrates the “culprits” are chiefly responsible for the obesity epidemic, researchers are quick to blame them even in the public eye…

Such confidence in one “culprit” is then often contradicted by public health proponent[s] advancing their favored target for intervention.

Due to the “complex reality” of the situation, the authors point out that some factors are not actionable in any practical way. For instance, a lot of adults have gotten fat because they quit smoking. But no responsible member of any profession would suggest that anyone should resume the nicotine habit for the sake of weight control.

Regarding the role of bacterial products in regulating metabolism and body weight, a category that has been explored is infection, because…

[…] the possible contribution of infections in the etiology of human obesity is often overlooked. Canine distemper virus (CDV) was the first reported obesity promoting virus… In mice infected with CDV, obesity develops after acute infection has abated and when no virus is detectable.

Also, there is a suspicion that the role played by bacterial products in metabolism and body weight regulation has not been considered. In this area of investigation, a lot of crazy things have been observed. For instance, take visceral fat in chickens. “Paradoxically, the increased adiposity due to SMAM-1 [an avian adenovirus] infection was accompanied by a reduction in serum cholesterol and triglycerides.”

Ad-36 is a human adenovirus capable of increasing adiposity not only in chickens but in non-human primates. In one experiment, it is said to have “increased whole-body insulin sensitivity and enhanced expression of genes involved in the adipogenic and de-novo lipogenesis pathway…” — and it spreads very fast.

Only a few adenovirus subgroups have been examined relative to adiposity. “Adipogenic potential of remaining the 45 known human adenoviruses has not been tested.” Of course, that was in 2009, so additional research has surely changed the statistic. Still, a search for several keywords reveals that since then, not much seems to have been done toward finding out about the adipogenic potential of the remaining almost four dozen varieties.

A federal government page says,

Sometimes the virus can be shed (released from the body) for a long time after a person recovers from an adenovirus infection, especially among people who have weakened immune systems. This “virus shedding” usually occurs without any symptoms, even though the person can still spread adenovirus to other people.

Just a few more words about human adenoviruses, or HAdVs, which are associated with “an array of diseases”:

HAdV is classified into seven groups (A-F). There are more than 100 serotypes, and approximately 67 serotypes (1-67) are known to be pathogenic in humans… HAdV can evade the immune response and produce persistent or latent infections.

Your responses and feedback are welcome!

Source: “Ten putative contributors to the obesity epidemic,” ncbi.nlm.nih.gov, November 2009
Source: “Transmission, CDC.gov, undated
Source: “Perspective on Adenoviruses: Epidemiology, Pathogenicity, and Gene Therapy,” NIH.gov, August 2019
Image by Dr. Yale Rosen Atlas of Pulmonary Pathology/CC BY-SA 2.0 DEED

Obesity Villains Exonerated

This is an extension of the recent post, “Obesity Villains Reconsidered,” which discusses an interesting 2009 paper in which multiple authors looked closely at many accepted or alleged causes of obesity. One of their reactions was to divide pretty much all those possible causes into two subheadings: “food marketing practices” and “institutionally-driven reductions in physical activity” — which for convenience, they called the “big two.” But they also went on to propose quite a number of other causes, in a “more thorough discussion of factors that may be contributing to the obesity epidemic.”

Myopic emphasis

They proposed that there has been a narrowly focused concentration on two very big concepts, both having to do with energy: how to get it, and how to spend it. At the same time, the characterization of those categories has grown ever more broad. Human nature is such that, in many departments of life, we seem unable to count higher than two. A thing is either this or that. It is either intake or output — but that insistence on duality is a sticking point.

The paper titled “Ten putative contributors to the obesity epidemic” spells out that while each unit of the “big two” contains many problematic elements, there are also quite a number of other potential hazards to worry about. They fall outside the purview of either intake or expenditure, yet still need to be accounted for. This paragraph encapsulates the crux of the problem:

[E]ven though some elements of the big two do very likely play some role in influencing obesity levels, we believe that an unquestioned assumption of their preeminence has led to the possibly ill-advised expenditure of public effort and funds on programs aimed at reducing population levels of obesity and has also reduced the exploration of other potential causes and the alternative obesity reduction programs that might stem from their identification.

Consequently, these authors point the finger at some hitherto blameless suspects. More intriguingly, after examining the cases against a few traditionally acknowledged obesity villains, those factors are let off the hook. Take fast-food establishments. A 2008 study showed that although people might consume a boatload of calories at a restaurant, “they largely compensated by eating less at other occasions…”

Of course, that all transpired some years back. Since then, the evidence against fast food has mounted and multiplied. There are indications that people who eat home cooking absorb less sugar and fat, and have lower cholesterol levels. Also, at home, there is more opportunity for portion control, although that could backfire. (“It’s my kitchen, I paid for the food, and by golly, I’ll eat as much of it as I please.”) Another element of domestic culinary art is that, of course, the (traditionally female) cook has more control over what ingredients go into a meal in the first place.

PE still counts

A 2012 meta-study looked at data from “observational studies, 20 cross-sectional studies, and 8 prospective cohort studies.” However, there were methodological differences between those studies, and the conclusions drawn turned out to be “far from conclusive.” A 2018 paper said it all in the title: “Frequency of Eating Out at Both Fast-Food and Sit-Down Restaurants Was Associated With High Body Mass Index in Non-Large Metropolitan Communities in Midwest.” No doubt, plenty of evidence for either claim could be found by a motivated seeker.

As for Physical Education in schools, the evidence that it has decreased is not convincing, and furthermore, “much evidence suggests that standard PE classes have no appreciable impact on obesity levels.” Again, this was stated in 2008, so it is appropriate to look for something fresher — like two reports from 2023. The first, from the University of Texas at Austin, bluntly states in its title, “Physical Education Policies in Schools Have Not Curbed Childhood Obesity.”

Over the past few years, many states have supposedly adopted the 150-minutes-per-week standard. But…

Researchers found that schools largely disregarded state laws and did not increase the time that elementary students actually spent in PE or recess. Relative to states that did not change their laws, states that passed increases did not see a decline in children’s body mass index, overweight prevalence or obesity prevalence.

“Closer oversight of schools would be needed to improve compliance with state PE laws,” said Paul von Hippel […] who co-authored the study. “Yet, even with better compliance, we estimate PE classes just don’t burn enough calories to make a noticeable impact on obesity. At least not as they’re currently conducted.”

But to balance the scales, another fairly contemporary article is titled, “PE classes vital to children’s physical and mental health.” It quotes pediatrician Dr. Rebecca N. Dudovitz affirming that PE classes are definitely helpful, especially post-pandemic, for both the physical and mental health of children. And as always, there are obstacles to the achievement of necessary goals. In far too many cases…

PE class is the only time exclusively set aside for exercise. That’s particularly true for children who do not have access to safe places to play outside of school. Families of students in underserved communities may not have the same resources or privileges of a safe environment for exercise in their neighborhood.

Do parents need to play a role in ensuring that kids move enough? Absolutely. Dr. Dudovitz makes five recommendations:

1. Carve out daily time for physical activity
2. Use fun competition as a motivator
3. Incorporate nutrition (a healthy diet reinforces performance and ambition to stay fit)
4. Encourage your child to join a sports program or organized after-school fitness activity
5. Limit time on video games and cell phones

Your responses and feedback are welcome!

Source: “Ten putative contributors to the obesity epidemic,” ncbi.nlm.nih.gov, November 2009
Source: “Association between eating out of home and body weight,” ncbi.nlm.nih.gov, February 2012
Source: “Frequency of Eating Out at Both Fast-Food and Sit-Down Restaurants Was Associated With High Body Mass Index in Non-Large Metropolitan Communities in Midwest,” ncbi.nlm.nih.gov, Jan 2018
Source: “Physical Education Policies in Schools Have Not Curbed Childhood Obesity,” UTexas.edu, 03/21/23
Source: “PE classes vital to children’s physical and mental health,” UCLAHealth.org/ 04/08/22
Image by Jaguar MENA/CC BY 2.0 DEED

Obesity Villains Reconsidered

The word “multifactorial” has been mentioned here many times before. Thanks to life being how it is, a plethora of factors will always be at work, on us and around us, in pretty much every aspect of human existence.

Take the example of auto accidents. Distracted driving is the main cause of them, and then there’s speeding, and drunk driving. Relative to those biggies, the collective impact of deer collisions may be small — but they are still potentially fatal; along with fog, potholes, tailgating, reckless lane-hopping, and other factors that despite being not so statistically prominent, are nonetheless meaningful. Even if deer cause only a fraction of a percent of vehicle accidents, they are still a factor. If those eventualities could be eliminated as factors, so much the better.

The same is true of some of the less frequent or more unlikely-sounding reasons for what has been called the obesity epidemic. Obesity appears to follow the pattern of having not only a gigantic, pervasive cause or two but an arsenal of little tricks to bring people under its sway.

Throwing ideas out there

Inspired by the news that over a billion humans are now obese, Joe Eisenmann, Ph.D., reflects on the many contributing factors that gang up to cause the ongoing epidemic. This writer is described as (among other things) a diverse scholar-practitioner and youth sports coach, who has been on the faculty of four different universities and published 180 scientific papers.

As an academic researcher, some years ago he was included in the group of highly respected obesity scholars who, with Dr. David Allison, wrote a paper called “Ten Putative Contributors to the Obesity Epidemic.” Bearing in mind that “putative” means commonly supposed, accepted or assumed, they are…

microorganisms
epigenetics
increasing maternal age
greater fecundity among people with higher adiposity
assortative mating
sleep debt
endocrine disruptors
pharmaceutical iatrogenesis
reduction in variability of ambient temperatures
intrauterine and intergenerational effects

That entire list would certainly not be endorsed by Dr. Pretlow, but illustrates what the authors meant by saying, “Human weight, body composition and obesity, like other human traits, are part of the multi-faceted complicated human phenotype.” The general multifaceted idea is sound, although experts have different opinions about specifics. The Abstract section of the work says,

While the evidence is strong for some contributors such as pharmaceutical-induced weight gain, it is still emerging for other reviewed factors. Considering the role of such putative etiological factors of obesity may lead to comprehensive, cause specific, and effective strategies for prevention and treatment of this global epidemic.

The authors seem to suggest that, when such important answers are sought, it is important to look at everything, in order to know what should be discarded. This paper proposes that the commonly understood reasons for obesity can be generally sorted into two groups — food marketing practices and institutionally-driven reductions in physical activity — which for convenience, are called the “big two.”

The authors say,

Our purpose here is to expand upon our brief discussions elsewhere and offer a more thorough discussion of factors that may be contributing to the obesity epidemic beyond those conventionally included within the big two.

Each major category includes a large number of sub-categories, some of which are manifestly more harmful than others — but they all do their share, in the big picture. On one hand, a marketing practice that can be regulated and enforced is the inclusion of accurate labels that make full disclosure of ingredients, caloric value, sell-by date, genetic interference, allergens, etc.

But much more difficult matters come under that marketing practice heading, too — like “food deserts.” Government bureaucracies cannot force corporations to build grocery stores where they don’t want to, and that’s that. “Institutionally-driven reductions in physical activity” are not easily addressed, either. It will take more than a few bike lanes and standing desks to make an appreciable dent in obesity.

Your responses and feedback are welcome!

Source: “The 25 Top Causes of Car Accidents in the US,” SeriousAccidents.com, undated
Source: “The Obesity Epidemic — more complicated than diet and exercise,” Substack.com, 03/04/24
Source: “Joe Eisenmann, PhD,” VoltAthletics.com, undated
Source: “Ten putative contributors to the obesity epidemic,” ncbi.nlm.nih.gov, November 2009
Image by Juhan Sonin/CC BY 2.0 DEED

What, No Party? No Cake?

A billion of anything is quite a landmark. A person might think it would warrant some kind of celebration. But no. The Lancet just went with a sober headline: “More than one billion people in the world are now living with obesity, global analysis suggests.” Here’s more:

In total, an estimated nearly 880 million adults were living with obesity in 2022 (504 million women and 374 million men)… Combined with the 159 million children living with obesity in 2022, this is a total of over one billion people affected by obesity in 2022.

The article talks about a study funded by a trio of venerable institutions and conducted by the NCD (Non-Communicable Disease) Risk Factor Collaboration, described as “a worldwide network of over 1,500 researchers and practitioners.” Ever since 1990, when global health authorities apparently started seriously keeping track, children and adolescents have become more and more obese. At the same time…

[…] rates of underweight fell among children, adolescents and adults, leading to obesity becoming the most common form of malnutrition in many countries.

Doesn’t that sound crazy? Even more confounding is a quotation from one of the study’s senior authors, Professor Majid Ezzati of Imperial College London, identifying the answer to both problems as the same: namely, to “significantly improve the availability and affordability of healthy, nutritious foods.” He also makes a point of mentioning the huge demographic shift. In the 1990s, obesity was a condition that mainly affected adults. Now, children and adolescents are experiencing obesity on a scale that would have been impossible to imagine back then.

From the report, here are just a few examples of the statistics:

Despite the most rigorous controls and conscientious procedures, it is doubtful that any study can ever guarantee total accuracy. Here is an example of why. Although more than 1,500 researchers took part in this effort, all the measurements on which it was based were of BMI (body mass index). While by no means totally discredited, BMI has been recognized as an imperfect standard, and many experts would much rather see everyone in the field switch over to the waist-to-height ratio.

Even with enthusiastic endorsement and total cooperation from the majority of professionals in the field, it is unlikely that such a drastic change could take hold completely within a short time span. But even more discouraging is the plain fact that, if BMI is a misleading criterion, when 1,500 researchers report conclusions based on it, that essentially translates into “misleading multiplied by 1,500.”

The authors of course acknowledge the inevitable shortcomings faced by any endeavor of this massive scale:

While BMI is an imperfect measure of the extent and distribution of body fat, it is widely recorded in population-based surveys, making analyses such as these possible. Some countries had little data and three had no studies, meaning their estimates are more uncertain. There were also differences in data availability by age group, with fewer data available for those aged five to nine years, and people aged over 65 years, increasing the uncertainty of estimates for these age groups.

“This new study highlights the importance of preventing and managing obesity from early life to adulthood, through diet, physical activity, and adequate care, as needed,” said Dr. Tedros Adhanom Ghebreyesus, WHO Director-General.

If human nature as it relates to food and eating were the only drawback, the prognosis would not be good. But several other factors are involved, mostly based on human nature as it impinges on everything else concerned with life on earth. These pessimistic words are from study co-author Dr. Guha Pradeepa of the Madras Diabetes Research Foundation:

The impact of issues such as climate change, disruptions caused by the COVID-19 pandemic, and the war in Ukraine risk worsening both rates of obesity and underweight, by increasing poverty and the cost of nutrient-rich foods. The knock-on effects of this are insufficient food in some countries and households and shifts to less healthy foods in others.

Your responses and feedback are welcome!

Source: “The Lancet: More than one billion people in the world are now living with obesity, global analysis suggests,” EurekAlert.org, 02/29/24
Image by Simeon W/CC BY 2.0 DEED