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

I have previously linked the obesity epidemic to global warming, suggesting that the solution to one of these problems is likely the solution to the other.

Here is now another spin to this idea from a study by Kevin Hall and colleagues from the US National Institutes of Health, Bethesda, Maryland, just published in PLoS.

Hall and colleagues calculated the energy content of nationwide food waste from the difference between the US food supply and the food consumed by the population. The latter was estimated using a validated mathematical model of metabolism relating body weight to the amount of food eaten.

Their calculations show that the US per capita food waste has progressively increased by ~50% since 1974 reaching more than 1400 kcal per person per day or 150 trillion kcal per year (enough to feed ~150 Million additional people).

They further estimate that food waste now accounts for more than one quarter of the total freshwater consumption in the US and ~300 million barrels of oil per year (or ~1/3 of Alberta’s annual oil production).

In addition to the methane and CO2 emissions from the production of this food that no one needs, even more of these gases are produced as the food decomposes in landfills.

The researchers speculate that this increased availability of cheap food creates a “push” effect (now that we’ve gone to the trouble of producing it, let’s make sure it gets eaten), that promotes caloric overconsumption and the development of obesity.

As further pointed out in a discussion of this article in the ECONOMIST,

“The cheaper food is, the more likely it is to be thrown away even before it is sold to someone who might actually eat it. Such supply-chain waste can be built into the price, and usually makes economic sense. Throwing away leftovers is often better business than risking running out of stock. Yet any waste of a valuable resource is offensive at a visceral level.“

I could not agree more.

AMS
Edmonton, Alberta

Hat tip to Kavita for drawing my attention to this article

Amongst the many environmental factors that can promote the development of excess weight gain, one of the most intriguing and persistent notions is the possible role of obesogenic environmental toxins.

No doubt, the presence of environmental pollutants is associated with “westernisation” and many organic pollutants tend to accumulate in adipose tissue where they can have substantial metabolic effects - at least in theory.

But how good is the evidence that environmental pollutants can in fact affect adipocyte growth and function?

This issue was recently addressed by Robert Sargis and colleagues from the University of Chicago, IL, in a study just published in OBESITY.

This study focused on the potential contributions of environmental pollutants that act as endocrine disrupting chemicals (EDCs) on glucocorticoid signaling, a major driver of adipogenesis.

The researchers screened various EDCs and found that bisphenol A (BPA), dicyclohexyl phthalate (DCHP), endrin, and tolylfluanid (TF)) had significant stimulatory effects on the glucocorticoid receptor. Amazingly, even minute (picomolar) quantities of these compounds markedly promoted lipid accumulation and adipocyte differentiation in 3T3-L1 preadipocytes.

Importantly, these effects required the presence of a weak differentiating cocktail suggesting that the effects of these compounds is mediated through synergistic effects with known modulators of adipocyte differentiation. Thus, these compounds appear to act as “accelerators” rather than “inducers” of fat formation. 

These findings raise a number of interesting possibilities: for e.g. I cannot help but wonder whether drinking sugary pop out of a glass bottle is perhaps less obesogenic than drinking the same number of calories out of a BPA containing plastic bottle or can?

AMS
Sapporo, Japan

While I am taking a brief break from clinics and other obligations (including daily blog posts), I will be reposting past articles, which I still believe to be relevant but may have escaped the attention of the 100s of new readers who have signed up in the past months.

The following was first posted on 24/11/07

The link between two major problems of our times, global warming and the obesity epidemic, may be closer than we think.

The following are a few random thoughts on why I believe solving one will go a long way to solving the other.

If we accept that a major contribution to the rising incidence of obesity is (energy) overconsumption and lack of physical activity, then reducing consumption and increasing physical activity will be important.

But reducing consumption and increasing physical activity will also help reduce global warming - here is why:

Over the past century, fossil fuels have increasingly displaced food as the energy source for human movement. Both occupational and domestic physical activity has been replaced by automation and labor-saving devices, all of which consume energy from fossil fuels. But not just automation, also the physical effort to move from one place to another is today largely dependent on fossil fuels.

As people get larger the fuels consumed to move the extra weight around only adds to the problem. It was estimated that in 2000, US airlines spent $275 million to burn 350 million more gallons of fuel just to carry the additional weight of Americans. Obviously, it also takes more fuel to move heavier people around on the ground whether this is in cars or on elevators, escalators or amusement park rides.

But increased use of fossil fuels is not just part of the activity equation. The use of fossil fuels is also intimately linked to our food. World-wide, agricultural activity, especially livestock production (including ruminant methane production, transport and feed), accounts for about one fifth of total greenhouse-gas emissions.

In most industrialised countries today the total energy put into food production vastly exceeds the food energy yield [see McMichael et al. for in depth discussion of this topic].

As energy inputs, mainly in the form of fossil fuels, have gradually increased, the energy ratio (energy out/energy in) in agriculture has decreased from being close to 100 for traditional pre-industrial societies to less than 1 in the present food system. Each calorie of food you eat may have consumed 10 to 50 calories in fossil fuels (the exact number depends on how you calculate this relationship - but no matter how you do it, the numbers are scary).

Processing 1 pound of coffee requires more than 8,000 calories of fossil fuel, the equivalent of one quart of crude oil, 30 cubic feet of natural gas or 2 1/2 lbs of coal. It has been estimated that the CO2 emissions attributable to producing, processing, packaging and distributing the food consumed by a family of four is about 8 tonnes a year. (For more on this click here).

Not surprisingly, many environmental organisations are now targeting built environments, transportation as well as food production and supply as major culprits in global warming. How do some of these issues relate to obesity prevention?

Rebuilding our cities to allow shorter trip distances will also allow changes in travel mode (e.g. walking or bicycling instead of driving). When it comes to both the environment and to obesity, urban sprawl is a killer!

Compact densely populated neighbourhoods where the majority of trips can be done by active transport paired with efficient urban public-transport systems powered by renewable energy would not only reduce local air pollution and greenhouse emissions but would also reduce traffic injuries and improve the safety of neighbourhoods (more people on the street!).

Creation of human-scale, mixed-use urban “villages” with unique identities, improved local services, neighbourhood events and activities, accessible public transport including high-quality pavements, cycle paths, lighting and public art will get people out and moving - thereby reducing both greenhouse gases and increasing physical activity. (for an in-depth analysis of these issues refer to Woodcock et al. in the Lancet series on Energy and Health).

Perhaps the key to both global warming and the obesity epidemic may be in living, working and eating local.

Is this utopia? To some perhaps, but the alternative is scary!

AMS

Yesterday, a big new item was a study by University of Alberta’s John Spence and colleagues published in BMC Public Health, that reported the increased likelihood of having obesity when living in neighbourhoods with a high Retail Food Environment Index (RFEI), i.e. a high ratio of fast food restaurants and convenience stores compared to grocery stores and produce vendors.

This finding was based on a representative telephone survey of 2900 individuals from the City of
Edmonton, who provided complete height and weight information. Data were adjusted for age, sex, socioeconomic status, employment status and level of education (the latter parameters were extrapolated from postal code information).

The odds of being obese were significantly higher, the greater the ratio of fast-food restaurants and convenience stores to grocery stores and produce vendors near the home. This association existed for establishments within an 800 m buffer around people’s homes but not for establishments within 1600 m of their homes, suggesting that it is indeed the proximity to the fast-food outlet that matters.

Interestingly, also yesterday, another study was in the news: this one, from Indiana University-Purdue University Indianapolis (IUPUI) contradicts the finding that living near a fast food outlet increases weight in children and that living near supermarkets, which sell fresh fruit and vegetables lowers weight.

In this study, the Purdue researchers looked at medical records of 60,000 children between the ages of 3 and 18 who went to an Indianapolis health care facility between 1996 and 2006. The children’s body mass index was tracked over the years, as was the development of neighborhood fast food restaurants, supermarkets and recreational facilities accessible to the public, such as basketball courts, pools and soccer fields.

Fast food restaurants had little discernible effect on weight, as did supermarkets that sell fruits and vegetables. In contrast, living close to a recreational facility marginally lowered the risk or excess weight.

Clearly, given the large number of confounders that can potentially affect the outcomes of such studies, I believe that the ultimate verdict is still out (personally, I tend to go with the Purdue study, given the far larger sample size and longitudinal nature of the study).

Obviously, neighbourhoods with more fast-food restaurants may have other characteristics that promote weigh gain than simply the presence of the fast-food restaurants themselves - or fast-food may have nothing to do with this at all - not a debate that is likely to end anytime soon.

As blogged before, I still think that fast-food outlets are a symptom or a “surrogate measure” of an obesogenic society rather than a direct cause of obesity.

AMS
Edmonton, Alberta