Arya M. Sharma, MD

Yesterday, I blogged about the rather weak relationship between BMI and health risks in the Manitoba Centre for Health Policy (MCHP) Report on Adult Obesity, and suggested that the results may have looked very different had the same data been analysed using the Edmonton Obesity Staging System.

Today, I want to address another interesting finding of this report, namely, the researcher’s attempts to identify the ’causes’ of obesity in Manitoba.

Variables examined included age, sex, marital status, education, employment, household income, activity restrictions, occupational physical activity, self-perceived life stress, satisfaction with life, self-rated mental health, sense of community, eating fruits and vegetables, physical activity leisure and travel, sedentary activities, current smoking, binge drinking, recent changes to improve health, food insecurity, and regular doctor.

Among these, location of residence, age, sex, education, employment, and marital status were particularly strong predictors of excess weight.

Interestingly, the psychological variables had little additional ‘effect’.

leisure– and travel–time activity level was the most strongly associated variable and showed a dose–response relationship—higher levels of activity were associated with lower likelihood of obesity. Other important variables were smoking (which was associated with a lower likelihood of obesity) and time spent in sedentary activities (more than 30 hours per week was associated with a higher likelihood of obesity).

Notably, only age and geography were significantly related to BMI values in youth.

Apart from the fact that such analyses cannot actually prove ‘causality’ as they are merely associated and therefore assumptions about modifying any of the modifiable variable will in fact reduce BMI, the researcher also made another notable observation:

“It is important to note that despite including many variables, this study was only able to explain a small amount of why people are obese. This means there are other reasons for the recent rises in weight, perhaps changes in our diets or our physical and social environment.”

Indeed, I would easily have predicted that factors not considered in this analysis, including parental BMI, birth weight, maternal weight at inception and birth of the participant, duration of sleep, etc. may well have accounted for some of the increase in obesity.

This should not detract from the importance of factors like sedentariness, stress, food insecurity and other variables that had some influence on obesity rates in this study.

It should, however, make us cautious in accepting the commonly held notion that the ‘root cause’ of obesity is simply increased sedentariness and eating too much.

Clearly, this is not the whole (and perhaps not even the biggest part) of this ’story’.

AMS
Edmonton, Alberta

Earlier this week, the Manitoba Centre for Health Policy (MCHP) released a report on Adult Obesity in Manitoba: Prevalence, Associations, and Outcomes.

The document (and especially the summary) makes an interesting read as it describes the rather complex nature of the epidemic and its impact on Manitobans.

While the analysis of about 35,000 Manitoba adults over the age of 18 who took part in one of three surveys between 1989 and 2008, documents the high prevalence of obesity and the fact that many health conditions are indeed more common in people with higher BMI’s, it also shows that these findings do not readily translate into higher healthcare costs till about a BMI of 33.

Thus, as the report summarizes:

“The Obese group almost always used more healthcare services than the other groups. However, the differences were small and often did not come into play until the very highest BMIs….people in the Obese group visited doctors more often than others. However, they only visited about 15% more overall. As well, the rise in visits only occurred from a BMI of 35 for men and 32 for women.
Likewise, costs of prescription drugs went up quite slowly until very high BMIs were reached. Hospitalizations were higher for those in the Obese group, but only for BMIs at or above 33. Home care use did not differ much either.”

This finding is actually not that surprising or unexpected.

Regular readers will by now be quite familiar with the Edmonton Obesity Staging System (EOSS), which was developed exactly because BMI is such an inadequate measure of risk or health.

Thus, I am confident that applying EOSS to this analysis would produce substantially different results than simply looking at BMI.

Thus, for e.g. our recently published analyses show that about 50% of people in the overweight category actually rank as EOSS 2/3. These individuals would considerably amplify the costs of people within the BMI 25-30 range - probably to the same level as EOSS 2/3 in the Obesity categories, while the obese EOSS 0/1 folks (of which there are about 20% in the BMI 30-35 class) would have costs very much like those of the EOSS 0/1 overweight people.

Such overlap in EOSS stages across BMI levels would readily mask any relationship between BMI and healthcare costs till rather extreme levels of BMI, where very few people will remain with EOSS 0/1 and the costs of being EOSS 2/3/4 would be substantially higher.

Thus, the ability of BMI to explore and interpret the cost of ‘obesity’ is limited, as it misses all of the ‘excess-weight-related’ health problems in the Overweight group while diluting the health care costs in the Obese group due to a substantial number of obese EOSS 0/1 people found in the moderately Obese group.

Thus, although I agree with the findings that higher health-care costs are only identifiable in individuals with moderate to severe obesity, I also sense that this report substantially underestimates the true cost of ‘excess-weight-related’ health problems.

The report also looked at ‘risk factors’ for obesity - a topic that I will comment on in tomorrow’s post.

A Summary of the Report is available here

The Complete Report is available here

AMS
Edmonton, Alberta

This morning, I am attending the annual scientific meeting of the Austrian Obesity Society, where I will be presenting a workshop on the management of severe obesity and a key-note lecture on the Canadian Obesity Network - a uniquely Canadian ’success story’ in terms of fostering professional collaboration and engagement in obesity research, prevention, and management.

Clearly, many of the issues that concern overweight and obese Austrians are very similar to what concerns us in Canada.

Thus, the topics at this meeting run the usual gamut from obstetric complications, gestational diabetes, in-utero programming and its impact on childhood obesity, to the use of behavioural, medical and surgical treatments for obesity.

Other talks focus on the impact of obesity on Austria’s health care system and discuss various aspects of health promotion.

Finally, there is also a whole session on the proposed Austrian Obesity Management guidelines, which emphasize managing both the psychological and somatic aspects of excess weight.

As elsewhere, bariatric surgery is also on the rise in Austria and this is clearly reflected in several talks on surgical management of severe obesity - a topic that will certainly continue to gain importance till we come up with better conservative treatments.

I would like to thank my Austrian colleagues Anita Rieder and Hermann Toplak for inviting me to speak at this meeting and being such wonderful hosts.

AMS
Seggau, Austria

This week I am attending the 47th EASD meeting in Lisbon, Portugal.

I know the Portuguese, while eating a lot of fish and having a traditionally ‘mediterranean’ style diet, also appear to have a preference for rich egg-based desserts (apparently, even the ’secret’ Coke formula is sweeter here) and cheeses.

Perhaps occasion to note that Portugal certainly has an obesity problem of its own, which as pointed out in a recent article by Pedro Marques-Vidal and colleagues in the Archives of Internal Medicine, is considerably under diagnosed and untreated.

Based on self-reported data from the Portugese National Health Survey conducted between February 2005 and January 2006 (participation rate, 76%) and data on dietary intake and physical activity, 15% of the 34 525 participants 15 years or older had a BMI of 30 or greater.

Among them, only 16% reported being told they were obese, of which, in turn, only 15% reported being treated for their condition.

Women, those with university level education, higher BMI levels, and/or cardiovascular risk factors including smoking, tended to be more aware of their obesity, while those with diabetes and higher BMI’s were more likely to report being treated for their excess weight.

Participants treated for obesity reported a lower consumption of bread, potatoes/pasta/rice, and a higher consumption of soup, milk/dairy products, salads/vegetables, and fruit.

In contrast, physical activity levels (available only on a handful of individuals) showed no difference between those who reported begin treated compared to those who were not.

As the authors note:

“…despite a nationwide program to fight obesity, less than one-fifth of obese subjects are diagnosed, and only 1 of 6 obese subjects diagnosed is treated. Our results also suggest that management of obesity is more frequently done with dietary than with physical activity.”

Does not sound like there is anything special going on in Portugal - I guess obesity is both underdiagnosed and undertreated in most places around the world.

This may be both due to lack of awareness and concern as well as due to the rather limited treatment options.

Looks like ‘globesity’ is alive and kicking in most places I go.

AMS
Lisbon, Portugal

While I am on a brief holiday in Berlin, I thought I’d rerun a few earlier posts that discuss the issue of measuring obesity and how such measures may or may not be helpful in obesity management - as many readers may not have seen these posts before, comments are very much appreciated.

The following was first posted on November 18, 2008

This week’s New England Journal of Medicine, features an article by Tobias Pischon on behalf of the EPIC (European Prospective Investigation into Cancer and Nutrition) investigators on the relationship between BMI, waist circumference, waist-to-hip ratio and mortality.

To me, this paper is of considerable interest - not least, because Tobias was one of my students back in Germany, who did his MD thesis on the effect of salt intake and obesity on chronic kidney transplant rejection under my supervision.

Of course, this paper also deals with a topic that I have often blogged about - i.e. the relationship between anthropometric measures and morbidity and mortality.

Pischon and colleagues studied 359,387 participants from nine countries during a mean follow-up of 9.7 years. After adjustments for age, educational level, smoking status, alcohol consumption, and physical activity, the lowest risks of death related to BMI were observed at a BMI of 25.3 for men and 24.3 for women.

After adjustment for BMI, relative risks among men and women in the highest quintile of waist circumference were 2.05 and 1.78, respectively, and in the highest quintile of waist-to-hip ratio, the relative risks were 1.68 and 1.51, respectively.

BMI remained significantly associated with the risk of death in models that included waist circumference or waist-to-hip ratio (P<0.001).

This study, essentially confirms what was already known, namely that the impact of excess body fat on mortality depends not only on the amount of excess fat (BMI) but also on its distribution (waist circumerence, waist-to-hip ratio).

Importantly, the measures of fat distribution are predictive of risk even in normal weight individuals with lower BMI’s, which challenges the use of cutoff points to define abdominal obesity.

On the other hand, as BMI increases, measuring fat distribution adds little to determining obesity-related risk. (which is why obesity guidelines do not recommend measuring waist cirumference in individuals with a BMI>40).

AMS
Edmonton, Alberta