Readers, who recently followed my postings from the XI International Congress on Obesity in Stockholm Stockholm last week on FaceBook, will perhaps recall a brief note on a talk by Garry Egger, Australia, raising the question whether we may have stayed too long at the “sweet spot” of economic growth resulting in both the obesity epidemic and climate change?

Together with his Australian colleague Boyd Swinburn, Egger has written a short book called, Planet Obesity, in which the two authors further elaborate on this notion.

The basic tenet of the very readable short treatise is simply put the following: obesity and climate change are both the seemingly inevitable consequences of economic growth that focusses solely on maximising (rather than optimising) consumption.

In every example cited in the book, economic development is inadvertently accompanied by an increase in body weight (first in the rich, then in the poor), till in highly economically “developed” societies obesity assumes epidemic proportions.

Readers of these pages certainly do not need to be reminded of the pandemic nature of obesity now affecting rapidly developing countries like China and India.

To state the converse, the authors present those rare examples of (involuntary) modern-era economic downturns (as in Cuba after departure of the Soviets or Nauro after the depletion of their natural super-phosphate bonanza), which were accompanied by a marked decrease in overweight and obesity associated with reduced incidence of complications like diabetes and heart disease.

While the authors fall just short of suggesting that all governments should now pursue the utopian goal of economic sustainability rather than growth, they do point to a few programs that may nudge things in a more positive direction.

Whether countries are quite ready to embrace instruments like personal carbon trading (PCT) or whether majorities can be found to support the creation of more equitable societies remains doubtful. But I certainly do support their views on the promotion of public transportation and restrictions on advertising to children.

Although I do not seriously expect anyone (especially no governments I know of) to pay the least attention to Egger’s and Swinburn’s message, I do very much recommend the read for a concise, well-rounded, and mind-opening discussion of the causes behind the causes behind the causes of the obesity epidemic.

AMS
Summerland, BC

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A single mom juggling two jobs and four kids may be right in thinking her life is complicated - but it is certainly not complex - at least not in the scientific sense of the word.

In medicine we also differentiate between procedures that are complicated (difficult, requiring skill) and complex (no clear solutions, unknown and incalculable risks, unpredictable outcome).

The best description of complexity was the “simplified” one I found in a book called Black Swans by Nassim Taleb:

“A complex domain is characterized by the following: there is a great degree of interdependence between its elements, both temporal (a variable depends on its past changes), horizontal (variables depend on one another), and diagonal (variable A depends on the past history of variable B). As a result of this interdependence, mechanisms are subjected to positive, reinforcing feedback loops, which cause “fat tails”…In lay terms, moves are exacerbated over time instead of being dampened by counterbalancing forces. Finally, we have nonlinearities that accentuate fat tails.”

As some readers may know, the term “fat tails” refers to an unexpectedly thick end or “tail” toward the edges of a distribution curve, indicating an irregularly high likelihood of extreme or catastrophic events.

How is this discussion of complexity relevant to obesity?

When we speak of obesity as a complex problem (and not simply a matter of calories in and calories out), we allude to the complex interactions of a multitude of societal, psychological, and physiological variables that do not allow a ready dissection as to cause and effect (are large portion sizes leading to obesity or do obese people drive the demand for larger portions?).

Perhaps more importantly, complex systems are difficult to model - tweaking the system at one end (e.g. banning pop machines from schools) may lead to unintended consequences elsewhere in the system (e.g. schools have less money to invest in sporting activities).

This means that coming up with system-wide interventions (or rather predicting their effect) with regard to reversing the obesity epidemic will prove challenging. Well-meaning legislators may suddenly find themselves in a game of “whack-a-mole” as the system responds in unpredictable and erratic ways. (Politicians may still choose to pass populistic laws to demonstrate that they are not unresponsive - but no results are guaranteed).

Because of the temporal dissociation that may well occur in complex system, even when solutions look like they seem to be working, only time will tell, as unintended consequences may take years (or generations?) to manifest themselves.

This should not be an excuse to throw up our hands in despair and do nothing. It should, however, be a warning to anyone, who believes to have the “simple” solution to the obesity problem, to tread cautiously and to always expect the unexpected.

AMS
Whistler, BC

Thorkild Sørensen

Yesterday, at the ongoing XI International Congress on Obesity, the 2010 ICO Award for Population Science and Public Health was awarded to Thorkild Sørensen from the University of Copenhagen. His studies from the early 70’s found early signs of the impending obesity epidemic in young Danish military recruits as far back as the 1960s.

His studies further suggest that this increase in obesity was related to “birth cohort” effects and can likely be traced to perinatal environmental factors rather than to influences acting on school age kids or adults. Indeed, based on his findings, Sørensen strongly recommends that we take a careful look at the historical dimension if we hope to identify the root causes of the current obesity epidemic.

As it so happens, I also had the pleasure of attending the launch of the new Wadd Society for the History of Obesity, with presentations from Professors George Bray, Stephan Rossner, and David Haslam at this meeting. The aim of the society is to promote interest in the history of obesity ranging from medical and pharmacological aspects to those of fashion, culture, art, and literature.

As all of this perhaps serves to remind those of us working in the field of obesity, that we must be very cautious before jumping to conclusions regarding whether or not recent environmental changes such as sedentary lifestyles, fast food, sugary soft drinks, television, or any of the many other factors that are being discussed are truly the root causes of the epidemic. While none of these development would be considered “healthy”, conclusive evidence as to their actual role in the epidemic of obesity is far from conclusive.

AMS
Stockholm, Sweden

For more posts on ICO 2010 click here

No worries, I am already holding my ears to avoid the screams of protest that I expect to get in response to this post.

But the idea that working moms may well play a noticeable role in the development of childhood obesity is indeed one that is suggested by Angela Pinot de Moira and colleagues from University College London, UK, in a paper just published online in the American Journal of Epidemiology.

The premise is simple: one of the most dramatic demographic shifts in the last decades has been the proportion of moms that work. From being the exception in the 60s, to becoming pretty much the norm for the majority of mothers today, this demographic shift has undoubtedly had profound effects on family life.

Not surprisingly, some have argued, that not having a parent at home (and traditionally this used to be the mom) may very much increase the risk of weight gain in offspring.

Thus, not only do “latchkey kids” have more freedom to eat unhealthy foods and spend afternoons slumped in front of the TV or computer, but long hours at work can also leave moms (or dads) short of time to prepare healthy family meals (ergo the dramatic rise in fastfood and family restaurants).

In addition, working mothers (or dads) may also have to drive their children to school rather than have the time to walk them there and working partents certainly don’t have the time to watch over their kids on the playground all afternoon or be at home in case their kids scrape a leg falling off their bikes or get beaten up by the neighbourhood bully.

So is this hypothesis borne out by the data?

To address this question, the authors examined members of a 1958 British birth cohort (age 7 years, n=8,552) and offspring (ages 4-9 years, n=1,889) born to mothers under age 30 years to establish whether risk factors for childhood obesity have changed over time (1965-1991).

The authors found that the prevalence of overweight/obesity had increased by more than 50% between generations and that parental BMI was strongly associated with offspring BMI.

But perhaps more interestingly, full-time maternal employment turned out to be positively associated with offspring BMI in childhood with an increase of 0.4-0.5 units in kids with working moms. This relationship was in fact stronger in the offspring than in the original cohort.

Maternal employment was found to have increased by more than 30% across generations, as a result of which, the population attributable risk maternal employment increased from 3.1% to 7.8% across generations.

In addition, the authors noted that smaller family size and fewer younger siblings were also associated with increased childhood BMI.

As argued by Elizabeth Warren and Amelia Warren Tyagi in their bestseller “The Two Income Trap: Why Middle-Class Mothers and Fathers Are Going Broke“, even if all kinds of issues may be linked to working moms, simply asking moms to stay at home is neither feasible nor socially desirable (incidentally, both authors are working moms).

Rather, other measures, including proper and affordable day care, accessible and supervised after-school activities and more flexibility in working hours may help moms (and dads) better meet the demands of their kids, thereby hopefully reducing their risk for obesity.

I wonder what my readers think of this hypothesis and what (if anything) can (should) be done about it.

AMS
Edmonton, Alberta

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de Moira AP, Power C, & Li L (2010). Changing Influences on Childhood Obesity: A Study of 2 Generations of the 1958 British Birth Cohort. American journal of epidemiology PMID: 20488872

Yesterday’s news was all about the new report on the declining fitness and increasing fatness of Canadians.

Although the role of physical activity to combat excess weight remains disputable, there is absolutely no doubt that increased physical activity is the key to better physical fitness (at any weight!).

So how do we get Canadians moving?

Probably not by demanding that they exercise more - indeed, we could probably easily plot the increase in gyms, fitness clubs, joggers, and sales of home exercise equipment vs. the increase in obesity and get a straight line that leaps right off the top of our chart.

Somehow I very much doubt that throwing even more gyms, fitness clubs or exercise equipment at the problem is likely to make any difference whatsoever.

Not that these facilities or gadgets are not effective when used; it is just that they are only (and probably only ever will be) used by such a small fraction of the population (mostly younger, female and affluent) that their use will probably never have a noticeable impact on public health.

If we want Canadians as a population to be more active, we will have no choice but to address some of the key factors that have led to this dramatic reduction in physical activity: automation and built environments that promote car dependency.

As pointed out by James Woodcock and colleagues from the UK in a recent article in The Lancet:

“Creation of safe urban environments for mass active travel will require prioritisation of the needs of pedestrians and cyclists over those of motorists. Walking or cycling should become the most direct, convenient, and pleasant option for most urban trips.

An increase in the safety, convenience and comfort of walking and cycling, and a reduction in the attractiveness of private motor vehicle use (speed, convenience, and cost) are essential to achieve a modal shift.”

Based on their modeling of the impact of increasing active transportation in London, UK and New Delhi, India, together with the known benefits of increased physical activity, the authors conclude that:

“Increase in the distances walked and cycled would lead to large health benefits. Largest health gains would be from reductions in the prevalence of ischaemic heart disease, cerebrovascular disease, depression, dementia, and diabetes.”

Are these changes likely to occur across Canada anytime soon? Probably not!

Can we perhaps get Canadians to be fitter by hoping that they’ll now all get on their treadmills at the end of their eight hour working days and hour-long commutes? Don’t hold your breath!

Do you drive a car, complain about poor roads, expensive parking, and simply hate those pesky pedestrians and cyclists?

Then YOU are the cause of Canada’s fitness dilemma.

AMS
Edmonton, Alberta