Obesity Drives Car Size?

The following quote is taken from a recent article in the ECONOMIST on the discontent of Americans with the economic state of their country:

Petrol prices, despite their recent retreat, hurt nearly everyone. Adam Julch, an enormous former college football star who is now a manager at a trucking firm in Omaha, Nebraska, complains that he had to trade in his pickup truck for a little Honda Civic. “I’m 350 pounds,” he says, “I feel like I’m in a clown car.”

Two aspects of this quote deserve comment:

1) Yes, larger people need larger cars to move them around - more larger people could mean more larger cars. This is not unlike the idea that it may not be the huge portion sizes in restaurants that lead to obesity but rather it is obesity that leads to larger portions sizes in restaurants (yes, large people need more calories and generally have bigger appetites than thin people) - so restaurants have to serve up portions large enough to feed even their hungriest customers.

2) The fact that this was a former athlete, as are many of my biggest patients, emphasizes that even being a highly successful competitive athlete does not protect you from severe obesity later in life.

Now there is food for thought. Feel free to comment.

AMS
Dushesnay, Quebec

Hat Tip to Michael Dwyer for bringing this quote to my attention

Accuracy of BMI for Diagnosing Obesity

Body mass index (BMI) is currently widely recommended and used as the best measure of obesity both in population and clinical studies. It dates back to the Belgian statistician Adolphe Quételet, who between 1830 and 1850 described this index as a way to characterize the level of adiposity in sedentary adults.

But how accurate is this index really to identify individuals with excess body fat?

This question was recently addressed by Abel Romero-Corral and colleagues from the Mayo Clinic, MN, USA, who analysed the relationship between BMI and body fat percent (BF%) as measured by bioelectrical impedence in 13,601 subjects (age 20-79.9 years; 49% men) from the Third National Health and Nutrition Examination Survey (Int J Obesity).

In this study, the authors defined obesity based on the World Health Organization (WHO) reference standard for obesity of BF%>25% in men and >35% in women.

BMI-defined obesity (>=30) was present in 19% of men and 25% of women, while BF%-defined obesity was present in 44% of men and 52% of women.

A BMI>=30 had a high specificity (men=95%, women=99%), but a poor sensitivity (men=36%, women=49%) to detect BF%-defined obesity. This means that while the BMI definition does identify the vast majority of men and women who have increased body fat, it also misses a significant number of individuals who have high percent body fat and would be considered obese by the BF% definition.

The diagnostic performance of BMI diminished as age increased and in the intermediate range of BMI (25-29.9), BMI failed to discriminate between BF% and lean mass in both sexes.

The authors conclude that accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. Thus, the currently recommended BMI cutoff of >=30 kg for obesity has good specificity but misses more than half the people with excess fat.

The scary part of these results of course is in the fact that based on actual BF% the prevalence of obesity in this population doubled! On the other hand, we know that %body fat or body composition alone is not a particularly reliable measure of health.

I prefer to continue using my operational clinical definition of obesity: the presence of excess body fat that threatens or affects your health.

Given the wide variation in the inter-individual susceptibility to develop adiposity-related health problems, the diagnosis of obesity and the question of whether or not reducing the proportion of body fat will indeed benefit your health will always remain a matter of clinical judgement.

AMS
Duschesnay, Quebec

2008 Obesity Boot Camp

Yesterday was the beginning of the 3rd Annual Obesity Boot Camp co-hosted by the Canadian Obesity Network (CON) and the Merck-Frosst/CIHR Obesity Chair at the University of Laval, QC. The annual Boot Camp is one of CON’s most successful capacity-building initiatives as evidenced by the continuing enthusiastic feedback from the over 50 students and new professionals who have so far attended the camp.

Contrary to what the name suggests, this is not a weight-loss camp for students challenged by excess weight (in fact given the quality of the food at the camp – keeping weight off is a challenge). Rather, the 9-day camp is a teaching and networking exercise, offered to 24 of the top young obesity researchers in the country (this year’s attendees come from 19 different universities across Canada).

This year’s Boot Camp was again kicked off by Ian Janssen from Queen’s University (Kingston, ON), who talked about the definition and epidemiology of obesity. Apart from presenting a succinct overview of the topic, he also presented some of his original research on the health costs related to obesity.

New to the camp this year was Diane Finegood, Director of the CIHR Institute of Nutrition, Metabolism and Diabetes and Professor at Simon Fraser University (Vancouver, BC), who spoke on complex adaptive. Some key properties of complex systems include heterogeneity, nonlinearity, feedback, learning, evolution, stochastics, relevance of tails, interdependence and emergence.

According to Finegood, the obesity pandemic needs to be viewed as an emergent property of people living in our current obesogenic environment. Because emergent properties, by definition, emerge when parts of a system do together what they would not do by themselves, they are generally not best understood or tackled using a reductionistic approach. Thus, it would be quite difficult to reliably predict the obesity epidemic or find solutions simply by studying individual components of our environment (e.g. urban sprawl) or any single component of human biology (e.g. genetics) in isolation.

Given the complexity of the issues, her take home messages were: all individuals matter; we need to match complexity to capacity; manage expectations; establish networks and teams; create competition and feedback loops; build intersectoral trust; monitor behaviours; measure effectiveness; adopt a whole-of-government approach (no single ministry can solve the problem).

Definitely a great kick-off to the 2008 Obesity Boot Camp.

AMS
Duchesnay, Quebec

What is Obesity?

Don't worry - I am not going to take off on a discussion about whether obesity is a disease or "simply" a risk factor. I am also not going to discuss again obesity definitions - anthropometric or otherwise.

Today's post is simply about an analogy that may help sharpen our clinical thinking around excess weight.

Think of someone who has an elevated plasma creatinine level (a marker of kidney failure) - the elevated creatine definitely tells us that there is something "wrong" with the kidneys, but that's about it. From the creatine level alone we can certainly tell that the kidneys are failing in their excretory function, but we cannot tell what is causing the kidneys to fail - is it a pre-renal, intra-renal or post-renal problem? We can probably list a 100 reasons why kidneys could fail and obviously the treatment (apart from some very general principles) will very much depend on the cause, i.e. the actual diagnosis.

In many ways, one can look at excess body fat simply as a sign or symptom of the fact that there is a something "wrong" with energy homeostasis. The excess body fat tells us nothing about what the problem is - sure, it's either excessive food intake or reduced energy expenditure - but that is like saying that the creatinine levels are elevated because the kidney is not excreting properly. I can think of a long list of reasons or factors that would contribute to excessive caloric intake or reduced energy expenditure: sociocultural factors, psychological factors, biomedical factors - figuring out what exactly is causing the energy imbalance is the real problem.

Only when we find what is causing the excessive intake will we have made a diagnosis of what is causing the problem - a few specific examples could include: poor meal planning, peer pressure, hedonic overeating, depression, obesogenic medications, binge eating disorder, defective satiety signaling, etc. The point is that till we know what is causing the overeating, we can't fix it, which means we will have little success in treating the weight problem and will be limited to a "symptomatic" approach - just eat less!

Similarly, when the problem appears to be lack of activity, again the question is what exactly is causing the problem. Obviously if the problem is lack of time our approach will hopefully be very different than if the problem is back pain or lack of motivation (a possible symptom of sleep apnea, exhaustion or depression). A "symptomatic" but useless approach would be to simply recommend 10,000 steps. No better than offering an ice-pack to someone with a fever.

Just as the term "kidney failure" only tells us that there is something "wrong" with the kidneys the term "obesity" only tells us that there is something "wrong" with energy homeostasis.

In itself, neither the term "kidney failure" nor "obesity" is a real diagnosis - they are only helpful if they prompt further investigation into what might have or is still causing the problem. Only when we find the cause will we be on our way to solving the problem.

AMS
Edmonton, Alberta

"Foie Gras" in Kids Risk Factor for Heart Disease

Nonalcoholic fatty liver disease (NAFLD), is now the most common cause of liver disease in children.

Although this condition is associated with insulin resistance its impact on other features of the "metabolic syndrome" is less clear.

In the July 15 issue of Circulation, Jeffrey Schwimmer and colleagues from the University of California, San Diego report on their findings from a case-control study of 150 overweight children with biopsy-proven NAFLD and 150 overweight children without NAFLD.

Children with NAFLD had significantly higher fasting glucose, insulin, total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, systolic blood pressure, and diastolic blood pressure than overweight and obese children without NAFLD.

Not only do these findings support the notion that, as in adults, NAFLD in overweight and obese children is strongly associated with multiple cardiovascular risk factors, they also show that as in adults, weight alone is not a reliable measure of cardiovascular or metabolic risk factors in kids.

Identification of NAFLD in a child should prompt global counseling to address nutrition, physical activity, and avoidance of smoking to prevent the development of cardiovascular disease and type 2 diabetes.

AMS
Edmonton, Alberta

Childhood Obesity Walks on Big Feet

Feet are remarkably complex structures exquisitely designed to buffer and carry the weight of our bodies. Whether standing, running, jumping, hopping, skipping - the feet do it all. Not surprisingly, painful feet affect the whole organism.

Interestingly, not much is known about the impact of increased body weight on foot architecture in kids. This knowledge is of course of great importance for orthopaedic and paediatric physicians with regard to prevention, clinical treatment and management of foot problems but also of obesity.

Now, Marlene Mauch and colleagues from the University of Tuebingen, Germany, studied the foot morphology of normal, underweight and overweight children in 1450 boys and 1437 girls aged 2-14 years (Int J Obesity). Foot morphology was measured using a three-dimensional (3D) foot scanner (Pedus, Human Solutions Inc., Germany) in a bipedal upright position. Twelve relevant 3D foot measures were recorded, as well as the children's age, gender, height and mass.

Five foot types were identified: flat, robust, slender, short and long feet. While normal weight children displayed an almost equal distribution of all foot types throughout childhood, overweight and obese children were more likely to have flat and robust feet, whereas underweight children tended to have slender and long feet.

The authors not only conclude that excess weight may have a significant effect on foot morphology but may also increase the risk for foot discomfort as a result of various musculoskeletal disorders. This in turn may keep the overweight children from being active thereby further promoting weight gain.

Clearly, the role of foot morphology and the maintenance of foot health in overweight and obese kids deserves more attention and further study.

I would add that careful analysis of foot morphology and recommendation of proper footwear, orthotics and exercises should be part of every assessment of an overweight kid - damage to feet resulting from well-meant but ill-advised physical activity at an early age could precipitate lifelong foot problems and prove a major obstacle to long-term weight management.

AMS
Edmonton, Alberta

$75 Million for Bariatrics in Ontario

Big news for patients with severe obesity in Ontario. As part of a $741 Million announcement for a provincial diabetes strategy, the Ontario Health Minister yesterday announced $75 Million in funding for Bariatric Centres of Excellence.

As outlined in the press release:

"Obesity is one of the main risk factors associated with diabetes. More than 50 per cent of type 2 diabetes cases in Ontario are associated with obesity. The government is improving access to bariatric surgery - a procedure that modifies the gastrointestinal tract to reduce food intake. This $75 million initiative will increase Ontario's capacity for bariatric surgery several-fold within two years and it will continue to increase thereafter. In 2006/07 169 procedures were performed in Ontario and 485 patients were funded for surgery out of country.

Ontario will enhance capacity for bariatric surgery in the province by:

- Providing bariatric education and training to health care providers
- Expanding bariatric surgical capacity
- Establishing pre and post bariatric surgery programs that will be linked to surgical programs"

Clearly, a first sign of relief for Ontarians who have thus far had to travel South of the border or scrape together the money for private bariatric surgery.

What I particularly like about the announcement is the emphasis on training health care providers and making sure both pre- and post-surgical care is in place. As I have blogged before, obesity surgery is not just about surgery. The actual operation is only a small technical piece in a complex life-long management plan.

I am particularly pleased by the announcement, because I believe that my past efforts in Ontario, including lobbying of the Government to provide better bariatric care, may in part have led to this announcement. As some readers may know, not only have I been quite vocal about this, but I was also the Clinical Co-Chair of the Health Technology Utilization Guidelines group that was contracted by the Ontario Health Ministry to prepare recommendations for Bariatric Surgery in Ontario.

We made it clear in this guideline document that bariatric care requires an interdisciplinary team and needs to take a chronic disease management rather than an acute-care approach to dealing with this issue.

Given that there is nothing different in the magnitude of the problem or the desperate need for bariatric care between Ontario and other regions of Canada, I can only hope that this announcement will be rapidly followed by similar announcements from other provinces.

Here in Alberta, we certainly have many of the components already in place (at least in the Edmonton Region) - and of course we'd be more than happy to share our experience with our colleagues in Ontario - the sooner we can get the services in place across all of Canada, the better for everyone.

AMS
Edmonton, Alberta