Dr. Sharma's Obesity Notes

Unbeknownst to many readers, the first 10 years of my research career was built largely on studying the effects of salt (or rather sodium chloride) on blood pressure.

In over 40 peer-reviewed publications, we described in excruciating detail the physiological effects of increasing and decreasing sodium intake, in many cases using single-blind randomised trial designs in hundreds of volunteers.

We not only examined the effects of salt on blood pressure but also on a wide range of physiological, metabolic and psychological parameters. We studied the effects on acid-base balance, we conducted genetic studies, we even performed in vitro studies on cells cultured from “salt-sensitive” and “salt-resitant” individuals.

In many respects, these studies left me as confused about the role of sodium on these parameters as I was before. Not that we did not report findings that helped us better understand the complex physiology of sodium homeostasis – it is just that we failed to convincingly demonstrate any major health implications of these findings. In some cases we even reported adverse consequences of sodium restriction resulting both in significant elevations in plasma lipids and insulin resistance (perhaps not surprising given that reducing sodium intake markedly stimulates both the sympathetic and renin-angiotensin systems – the very systems we seek to block to reduce cardiovascular risk).

That was almost 20 years ago – the field does not appear to be much clearer today.

Thus, although surprising to some, I must admit that I was by no means surprised by the report on sodium released last week by the Institute of Medicine, with the rather revealing conclusion that,

“…the evidence from studies on direct health outcomes was insufficient and inconsistent regarding an association between sodium intake below 2,300 mg per day and benefit or risk of CVD outcomes (including stroke and CVD mortality) or all-cause mortality in the general U.S. population.” (or any other population for that matter)

This is not to deny that despite considerable methodological problems (not least in the actual measurement of salt intake), there is evidence to support the idea that higher salt intake may affect blood pressure and possibly cardiovascular risk. However, the data is certainly  far less conclusive than food bloggers and health activists would lead us to be believe.

Not surprisingly, the same activists and organisations are now up in arms stopping just short of criticizing the scientific credibility of the IOM expert committee – no doubt, the same folks would have been applauding the conclusions of this “illustrious panel”, had the findings been more in line with their own activist agendas.

What is perhaps even more infuriating to those who have always considered the issue of sodium recommendations a slam-dunk case is the statement by the IOM that, there is in fact no basis on which to draw recommendations for the general public in recognition of the fact that significant proportions of the population may require higher sodium intakes and may even be likely to suffer harm from overly enthusiatic sodium restriction.

While I have no illusions that this report will in any way put the century old debate to rest (indeed the report calls for further research), I think that there is a much bigger message in this report that should let us tread cautiously when it comes to dietary recommendations in general.

Let us remember that associations (on which so many of our assumptions about healthy diets depend) simply do not prove causality, even when backed by seemingly plausible biological hypotheses derived largely from rodent toxicology. We should also remember that fancy statistical predictions on the vast number of lives lost or saved by altering the population intake of this or the other nutrient, are generally based on sometimes rather heroic assumptions that may well explain whey they are rarely (if ever) borne out by actual interventions.

Thus, whether we are talking about salt, fat, carbs, sugar, fibre, gluten, calcium, Vit D, dairy or red-meat, a degree of humility in advocating for policies and other measures to reduce or increase this or the other is generally in order.

Seldom in the field of nutrition are things as cut and dried as some will have us believe – if only food were as simple as tobacco.

AMS
New Delhi, India

Disclaimer: I was invited to be on the IOM Expert Committee but had to decline due to other obligations.

Not quite, although this does make for a good headline.

The actual story, which accompanies the global media reports of the underground smuggling operation that illegally routes KFC contraband to Gaza, however does illustrate the lengths to which people will go to obtain their crunchy fat, salt and sugar fix.

The report in the International Herald Tribune describes the distance KFC has to travel as,

“…a journey that involved two taxis, an international border, a smuggling tunnel and a young entrepreneur coordinating it all from a small shop here called Yamama — Arabic for pigeon.”

According to this report, the entrepreneur, a Mr. Efrangi (aka “the Kentucky guy”),

“..has coordinated four deliveries totaling about 100 meals, making about $6 per meal in profit. He promotes the service on Yamama’s Facebook page, and whenever there is a critical mass of orders — usually 30 — he starts a complicated process of telephone calls, wire transfers and coordination with the Hamas government to get the chicken from there to here.”

While the report focuses on the “resilience” of the Gaza inhabitants, who are merely seeking to live a “normal life”, the story does speak to the lengths that people will go still their “cravings”.

While Mr. Efrangi, for logistical reasons, limits his orders to chicken pieces, fries, coleslaw and apple pie, he may not be in business for long.

As the Tribune reports,

“A Gaza businessman who asked to be identified only by his nickname, Abu Ali, to avoid tipping off his competitors, said he applied for a franchise from KFC’s Middle East dealer, Americana Group, two months ago. Adeeb al-Bakri, who owns four KFC and Pizza Hut franchises in the West Bank, said he had been authorized to open a restaurant in Gaza and was working out the details.”

Throughout human history, people have desired what is most difficult to get – bans and prohibitions have always made stuff more worth having than before (whilst upping the “cool-factor”) – apparently, junk food is no exception.

As an interesting side note, which perhaps speaks to the “addictiveness” of the KFC formula, some readers may recall that KFC (now belonging to PepsiCo) was at one time owned by R.J. Reynolds (now RJR Nabisco) – the makers of Camel, Pall Mall, Winston and other “choice tobacco products”.

AMS
Edmonton, AB

Professor Shiriki Kumanyika, University of Pennsylvania, Philadelphia

Based on the simplistic notion that excessive weight gain is merely a matter of calories-in and calories-out, conventional individual-level approaches to obesity have long focussed on restoring energy balance in individuals by attempting to influence energy intake and output (with rather modest success).

What affects weight gain in individuals, may well also influence weight gain in populations, at least that is the underpinning idea of the ecological approach to addressing obesity. But, as in individuals, interventions based on this notion are far from straightforward to implement or sustain.

This may well be, because, as at the individual level, complex sociocultural and psychological (not to mention biological) factors tend to occur that serve to push the energy balance towards the positive side of the equation – this is particularly true for minority and marginalised populations.

Thus, as presented by Shiriki Kumanyika from the University of Pennsylvania  at the 20th European Congress on Obesity in Liverpool, social inequalities can make certain population seqments particularly vulnerable for obesogenic factors.

In this context, she emphasised that the term “vulnerability” itself can be discriminating and should be clearly defined in the context of social inequalities that face certain population groups (e.g. ethnic minorities) rather than in terms of “deficits”.

In her talk, she presented an overview of her work demonstrating the markedly increased obesity rates in black women, American Indians and Mexican Americans in the US. As she noted, even in the context of clinical trials, not only do participants from these groups show less weight loss with interventions but also gain weight more rapidly when randomised to the control group.

While the nature of foods and activity options available to whose with limited resources accounts for some of the increased risk, it turns out that higher income does not appear to be protective early in the nutrition-economic transition. Rather, during this transition phase, upward mobility may actually further increase the risk of obesity as behavioural risks (increased caloric intake, sedentariness) become more “affordable”.

In order to better understand these patterns of differences in ethnic minorities, a network consisting largely of black American researchers, has developed a “Community Energy Balance” framework.

At the community level energy balance is mediated through the many factors that directly or indirectly affect food intake and physical activity.

This framework leads to the identification of a wide range of potential intervention targets at the levels of the community, family and individuals.

Other elements of this framework also consider cultural-contextual influences that influence obesity including historical experiences and adaptations, type of minority status, structural influences, and sociocultural influences.

The hope is that although both socio-economic status and ethnic differentials are important, this framework will facilitate a systematic analysis and identification of possible solutions to the inequalities that affect these minority populations.

However, whether or not such interventions will prove more effective in communities than current individual-based interventions clearly remains to be seen. Knowing the intrinsic property of complex systems (including communities) to often respond and adapt in unpredictable ways, often with unintended consequences, it is by no means clear as to which community based approaches to addressing inequalities or other drivers of obesity will ultimately tip populations towards the negative side of the energy balance equation.

AMS
London, UK

Theresa Marteau, Director Behaviour and Health Research Unit, University of Cambridge

The second morning of the 20th European Congress on Obesity here in Liverpool was kicked off by a presentation by Theresa Marteau, Cambridge Institute of Public Health, on the use of “choice architecture” to “nudge” individuals towards adopting healthier behaviours.

Given the limited effectiveness (some may say “failure”) of attempts to change population behaviours based on conscious, goal directed, reflective interventions, “nudging” attempts to change behaviours through non-conscious, habitual or automatic interventions.

The idea of nudging, defined by Thaler and Sunstein as

“..any aspect of the choice architecture that alters people’s behaviour in a predictable way without forbidding any options or significantly changing their economic incentives”,

is not a new idea to social psychologists and is based on the observation that our conscious processes are finite and that most of our responses to the environment occur below our conscious awareness.

Thus, while previous approaches to changing health behaviours have primarily focussed on conscious cognitive approaches, newer models attempt to change behaviours by targeting the sub-conscious non-reflective processes that underly these behaviours.

In her talk, Marteau described the results of a large-scale scoping review on use of nudging interventions for tobacco-, alcohol-, diet- and physical activity-related behaviours. Her analysis included ~350 articles describing two types of interventions that altered either the properties (ambience, functional design, labelling, presentation, sizing) or placement (availability, proximity) of objects or stimuli within the micro-environent where the behaviour is happening. In addition the analysis looked at priming and prompting interventions.

All of these approaches have in common that they typically require minimal cognitive engagement and can potentially influence many people at the same time. In addition, health nudging, by avoiding the use of literacy and numeracy, may be able to reduce social patterning thus reducing health inequalities.

To date, most of the work on nudging has been done in the context of dietary behaviours, mainly on food labelling and sizing.

As one may expect, studies in experimental settings have shown effects of ambience (e.g. effects of the tempo of music on speed of eating), functional design (e.g. change in packaging), labelling (e.g. use of exciting names or cartoon characters on healthier foods), proximity (e.g. product placement on the shelf), or prompts (e.g signs or announcements) on behaviours.

Thus, for example, ongoing research suggests that simply putting healthier foods at the ends of aisles changes shopper behaviours largely independent of pricing, suggesting that simply changing the placement of foods may be far more effective than changing pricing (e.g. taxation).

The big question, however, is whether these effects are indeed sustained and have large enough effect sizes. So far, the data on this is not clear, which is why Marteau and colleagues are currently working on a synthesis of evidence to see whether such nudging interventions do indeed influence health behaviours outside the laboratory.

In the real world, healthy nudges have to compete with unhealthy nudges – e.g. images or labels warning against overconsumption of fast food have to compete with the strong nudges created by the common association of fast food advertising and images with sporting events – this may well be an insurmountable obstacle given the almost limitless tool box and financial resources of the food industry.

Marteau also addressed the acceptability of nudging interventions. As one may expect, less intrusive interventions such as placing or health prompts were found to be far most acceptable than taxing, pricing, or limiting portion size, which are generally seen as overtly limiting choice.

Ultimately, the issue of acceptability will be the rate-limiting-step for legislators, who need to align public and political wills. This is something that is unlikely to happen without stronger evidence to support broad acceptability of such measures. Countermeasures by industry and the voices of those who oppose coercive paternalism will clearly further limit political enthusiasm for legislative interventions.

On a happier note, Marteau notes that there may be somewhat greater acceptance for choice architecture interventions in children and young people.

Whether or not her optimism is warranted, remains to be seen.

AMS
Liverpool, UK

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Continuing my discussion of the paper by Julia Temple Newhook, Deborah Gregory and Laurie Twells from the Memorial University of Newfoundland, St. John’s, published in the Journal of Social, Behavioral, and Health Sciences, on what causes some people to gain weight, we turn to what the authors describe as, “Gradual Processes”.

Thus, in their extensive interviews with individuals seeking bariatric surgery, although most interviewees focused on explanations with a considerable sense of self-blame, many did report social structural factors as playing an important role in their weight gain, without using these as “excuses”.

“Zoë pointed out that outdoor exercise was too difficult for her in winter conditions, and indoor exercise in a gym was out of her reach financially, and gave specific policy recommendations: “They’re always telling people to lose weight, that we’re an overweight province. Well, help out a bit. Make gym memberships a little more cheaper, make it a little more accessible to people.”

Other barriers included occupational and domestic work schedules:

“When you’re sitting at a desk 40, 45, or 50 hours a week, you’re trying to establish yourself so that people are looking to you, so you get promotions as opposed to someone else, so you’re putting in those extra hours and you’re coming home tired. You’re sitting down for supper, and then it’s 7:00 at night.Okay, when do I do anything now?”

“Wanda explained, “I got the two kids. I have a gym membership, a family gym membership; it’s just that we never get there. I work all day. When I get home I’m tired. … Just finding the time is hard.”

As the authors note, leisure time distribution is a social inequality that particularly affects those with less income as well as mothers of young children.

Furthermore, social inequality related to the risk for occupational injuries with subsequent weight gain are likewise often not seen as related to the social determinants of health.

Finally, built environments and the cost of weight-loss programs were seen as contributing factors that made weight management efforts difficult or unsustainable.

I am sure that readers will have their own social determinants to contribute to this list.

AMS
Berlin, Germany