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Thursday, July 31, 2008

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.

Dushesnay, Quebec

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

Wednesday, July 30, 2008

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.

Duschesnay, Quebec

Tuesday, July 29, 2008

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.

Duchesnay, Quebec

Monday, July 28, 2008

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.

Edmonton, Alberta

Friday, July 25, 2008

"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.

Edmonton, Alberta

Thursday, July 24, 2008

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.

Edmonton, Alberta

Wednesday, July 23, 2008

$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.

Edmonton, Alberta

Tuesday, July 22, 2008

What's the Ideal Weight for a Japanese?

Regular readers of my blog know about my issues with a weight-based definition of obesity. As I have repeatedly pointed out, good health is possible over a wide range of body weights and weight alone is a rather poor measure of overall health.

Not surprisingly the same appears true for the Japanese. At least according to a paper just out in OBESITY, in which Atsushi Hozawa and colleagues from the Shiga University of Medical Science, Otsu, Japan, examined the relationship between BMI and all-cause mortality in 8,924 Japanese men and women without stroke or heart disease.

During 19 years of follow-up, 1,718 deaths were observed. As in other populations, the relationship between BMI and fatal events was U-shaped. Risk of total mortality was highest in participants with BMI <18.5 and lowest in participants with BMI 23.0-24.9. These findings persisted even after excluding the first 5 years of follow-up with a focus on healthy participants. For both the full sample and healthy participants, all-cause mortality risk did not differ between BMI ranges 21.0-22.9 and 23.0-24.9.

These data are particularly of interest because recent recommendation from the WHO and others suggest that a BMI > 23.0 should be considered overweight in Asian populations.

This would obviously make little sense if mortality is in fact lowest in individuals with BMI between 23.0-24.9.

Once again, this study illustrates the problem with BMI-based definitions of obesity which fail to take into account the huge inter-individual variability in the impact that excess body fat can have on health.

While there is no doubt that some Japanese with a BMI as low as 23 may have a full blown "metabolic syndrome", others (perhaps the majority) at the same BMI may be perfectly healthy.

Clearly it is time for a health-based rather than a solely anthropometric classification of obesity.

Edmonton, Alberta

Monday, July 21, 2008

Do Workplace Wellness Programs Promote Discrimination?

The obesity epidemic is costing employers. Earlier this year, The Conference Board estimated that obesity-related health problems cost US companies an estimated $45 Billion each year in medical coverage and absenteeism - more than smoking or problem drinking.

Not surprisingly, employers and health care plans have long recognized the importance of promoting and perhaps even coddling employees into participating in "wellness" efforts. The idea is a no-brainer: healthier employees are more productive - a great investment for any company.

But with any good idea, the devil is in the details. The legal limits and potential for well-meant wellness programs (especially when promoted by health-care plans and payers) for promoting discrimination are discussed in a recent article by Michelle Mello and Meredith Rosenthal from the Harvard School of Public Health published in the July 10 issue of the New England Journal of Medicine.

In their analysis, Mello and Rosenthal focus on the impact of the nondiscriminatory provisions of the US Health Insurance Portability and Accountability Act (HIPPA) of 1996, which bars health plans and issuers of group health insurance from discriminating on the basis of a health factor.

The general rule is that no person can be denied or charged more for coverage than other "similarly situated" persons because of health status, genetic history, evidence of insurability, disability, or claims experience. In this context "similarly situated" refers only to an employment-based classification, such as full-time or part-time, not on health factors.

As a result of this, health plans can only opt not to provide coverage for particular health conditions, if this applies to all "similarly situated" individuals and is not based on whether or not people actually have that health condition.

While HIPAA is designed to prevent health discrimination, it does allow insurers and health plans to reward members for participating in health-promotion programs (e.g. reduced premiums, payouts, etc.) as long as the reward is open to all members (irrespective of whether or not they actually have a health problem). HIPAA, however, makes it particularly difficult for plans to tie these rewards to actually achieving an individual health target - i.e. it allow rewards for participation but not success.

In the rare cases that insurers do tie rewards to achieving health targets, there are important restrictions in place. In this regard, the provision that in cases where it is "unreasonably difficult" or "medically inadvisable" for a person to satisfy the health standard owing to a "medical condition" must be offered a reasonable alternative standard.

As pointed out by Mello and Rosenthal, the problem with this restriction is that no definition of "medical condition" is provided. So whether or not someone with overweight or obesity can be expected to achieve a target weight ultimately depends on whether or not the prior presence of excess weight is defined as being a "medical condition" or not - obviously, this leaves the room wide open for weight-based discrimination. It is certainly easier for someone with little excess weight to achieve an arbitrary "ideal weight" than for someone with a lot to lose - no matter that actually keeping the weight off becomes an exponentially bigger challenge the more you lose.

It is clear that whether or not excess weight in a given individual is caused by genetic predisposition, psychosocial factors, comorbidities or obesogenic medications, or, is simply a matter of poor "choices" and "sloth" will in most cases remain a matter of debate.

To me, the overall problem remains in the focus of employers, insurers and policy makers in general on the promotion of individual changes rather on than shifting society as a whole to a healthier lifestyle for everyone.

Given the multidimensional sociocultural, psychological and biomedical nature of obesity, answering "chicken and egg" questions or trying to pinpoint the primary causal factor is nigh impossible.

Perhaps one solution is to take "weight" out as a measure of health - either as a promoting factor or as a target.

As I have pointed out repeatedly, good health is possible over a surprisingly wide range of body weights and there is a wide variation in individual susceptibility to "weight-related" health problems. No one weight cuttoff will work for everyone - clearly, we have no idea what a good weight target should be, as our definitions of healthy weight are entirely defined on the presence or absence of comorbidites and/or functional limitations in a given individual or on actuarial morbidity and mortality statistics that, in turn, are simply not helpful when dealing with individuals.

I certainly do not envy the lawyers and policy makers who have to address this complex issue with "legalese". I am glad I am just a simple clinician helping patients conquer their obesity one step at a time.

Look forward to any comments on workplace wellness and its legal framework in Canada (or in Germany from my German readers).

Edmonton, Alberta

Friday, July 18, 2008

Overeating is a Symptom

Last week, I blogged about the results of a study showing an association between vital exhaustion and weight gain.

This blog posting prompted Sharon Kirkey (award-winning health journalist and diligent reader of my blog) to explore this issue further by actually talking to the researchers themselves. Her article appeared yesterday via the Canwest News Service and contains far more details than I bothered to report in my blog.

For e.g. Sharon lists the actual questions Bryant and colleagues used to explore the presence of vital exhaustion. I found them most interesting so I list them below:

- Do you often feel tired?

- Do you wake up repeatedly during the night?

- Do you have the feeling that you have not been accomplishing much lately?

- Do you believe that you have come to a 'dead end'?

- Do you lately feel more listless than before?

- Do little things irritate you more than they used to?

- Does it take more time to grasp a difficult problem than it did a year ago?

- Do you have increasing difficulty in concentrating on a single subject for long?

While to me none of these questions seem particularly specific and are likely to get a "yes" response from a lot of people (hey, even I have to say "yes" to some), I guess when you have to say "yes" to most or all of them, you are probably not hopping around like the Energizer Bunny or scrambling to follow diet plans.

Sharon quotes me as saying:

"Nobody is claiming all of obesity is exhaustion, but if people are clearly eating more than they need the question is not (just) how to get them to stop, but why, exactly, are they doing that. Maybe you're losing your job. Or you're overworked. Or it's some private issue that needs to be addressed. You don't fix obesity by giving people a copy of Canada's food guide. You have to try to understand what it is that's contributing to the weight gain."

Exactly! Obesity is a symptom of overeating, which in turn is a symptom of something else that's going on: it can be that you simply lack the knowledge about healthy nutrition or caloric content of foods, but it can also be a symptom of emotional (e.g. depression, vital exhaustion) or biological (e.g. MC-4 receptor defect) issue, medications (e.g. clozapine) or any number of other reasons I can think of.

Always remember: overeating (and/or sedentariness) is not a diagnosis - overeating (and/or sedentariness) is a symptom!

Edmonton, Alberta

Thursday, July 17, 2008

Walk and Work

Two days ago I reminded readers that not too long ago, people were actually paid to be physically active. Today, choosing to be physically active actually costs money (not to mention time).

So the big challenge is, how do we reintroduce activity into the work place so that people can actually be physically active at work again (allowing them to lounge around the couch in front of the TV when they get home).

Well, one obvious solution is to create a workspace where someone can get a workout in while on the computer. That is exactly the idea behind the "Walk Station" a desk that comes matched with a treadmill instead of a chair.

The device, the science (and the hype) behind it are described in an article from the Edmonton Journal from which I quote:

The device allows people to work on their computers while walking on a treadmill at a slow speed of up to three kilometres per hour, enabling small amounts of movement that supporters say have the potential to reap big health benefits.

The product, made by Details, a unit of Michigan-based office furniture maker Steelcase, is selling 30 to 40 units per week, according to company president Bud Klipa.

The Walkstation was unveiled last year based on research from James Levine, a researcher at the Mayo Clinic, who contends that fitness can be improved through small, modest movements for people who are otherwise sedentary.

Levine's research indicates that people who use the Walkstation can increase energy expenditure by 100 calories per hour when walking at a 1.6 kilometres (one mile) per hour, helping weight loss.

The treadmill, which costs around $4,500 for a base model, never exceeds a speed of three kilometres per hour, which, according to the manufacturer, allows most people to use it for a few hours each day.
So here are my questions:

Where is the evidence that this device will actually promote weight loss?

What will prevent this device from going down the same path as previous workplace health initiatives - embraced by the already fit, ignored by the people who need them most?

Will it increase weight-based discrimination at the workplace - the thin people are walking, the overweight are not - no one stops to ask why - back pain? osteoarthritis? depression? plantar fasciitis? - excuses, excuses! Who cares!

Although is seems like a good way to reintroduce activity into the workplace, it is still "useless" activity, i.e. you are not actually paid to walk - or in other words, you don't really have to walk to get your job done.

While I personally would probably not mind having this device, I can see all sorts of problems - anyone out there who's experienced this or a similar device - I'd love to hear how this has influenced intra-office dynamics.

I will maintain my scepticism on this being the answer till I see some actual data.

Edmonton, Alberta

Wednesday, July 16, 2008

Epicardial Fat and Weight Loss

Increased visceral fat or "ectopic" fat deposition is associated with insulin resistance and increased cardiovascular risk.

Traditionally, the term visceral fat has been used to describe the omental and mesenteric fat located inside the abdomen. Over the last several years, this concept has been expanded to include other "ectopic" fat depots including the liver and the heart.

Recognition that the fat located around the heart can be a marker of visceral fat was pioneered by Gianluca Iacobellis, who joined me as a clinical research fellow a few years ago at McMaster University and has since been recruited to their faculty.

In this month's issue of OBESITY, Iacobellis reports on work we collaborated on just before I left McMaster to relocate to the University of Alberta demonstrating that epicardial fat is a sensitive marker of changes in visceral fat associated with weight loss.

In this study in 20 severely obese subjects who underwent a 6-month very low calorie diet weight loss program resulting in a 20% loss of original body weight, waist circumference decreased by 23% whereas epicardial fat thickness decreased by 32% of baseline.

Based on this finding, we suggest that measurement of echocardiographic epicardial fat thickness may provide an additional tool in understanding the metabolic risk associated with variation in fat distribution. Perhaps, more importantly, echocardiographic measurement of epicardial fat can serve as a simple and relatively inexpensive tool to assess changes in visceral fat with weight loss (or gain) in clinical practice.

Certainly beats simply measuring waist circumference (a rather crude surrogate measure of intra-abdominal fat) or the rather more expensive CAT or MRI study.

Edmonton, Alberta

p.s Thanks to Navneet Singh and Sean Wharton for their great help with this study and to all the patients who volunteered their time for these measurements

Tuesday, July 15, 2008

Mitochondria and Obesity Revisited

Several months ago I blogged about the results from a Finnish twin study that found lower mitochondria numbers and disturbed mitochondrial energy metabolism activity in fat cells from identical twins who were leaner than their genetically identical co-twins. These impairments correlated with critical clinical measures of obesity including liver fat accumulation, reduced whole-body insulin sensitivity, hyperinsulinemia, hypoadiponectinemia and adipocyte hypertrophy.

In this month's issue of OBESITY, Tomas Gianotti and colleagues from the University of Buenos Aires, Argentina, report a significantly lower mitochondrial-to-nuclear DNA ratio (mtDNA/nDNA) in insulin resistant (IR) adolescents recruited out of a subset (n=175) of a cross-sectional, population-based study of 934 high school students. In this study, the mtDNA/nDNA ratio was also inversely correlated with HOMA index, a crude but simple measure of insulin resistance.

This study is very much in line with the notion that obesity-prone individuals may have impaired mitochondrial number and/or function resulting in increased risk for obesity.

From the aforementioned twin study, we know that the decreased number and function is not corrected by weight loss.

Indeed the question is whether or not mitochondrial number and function can be increased by prescribing higher activity levels? If yes, how much activity will be needed to reverse these changes? And most importantly, will people with impaired mitochondrial function actually be able to enjoy exercise enough to actually stick with this prescription?

Perhaps it is not obesity that causes impaired mitochondrial function but rather impaired mitochondrial number and/or function that predisposes to obesity. This impairment could be genetic but also due to intrauterine programing or perhaps simply luck of the draw (remember - all mtDNA comes from your mom).

Of course this is not an "excuse" for obesity as is often misinterpreted when data on the genetics and biology are presented. However, it is clear that if you have impaired mitochondrial number and/or function you are much more likely to become obese in an environment that promotes sedentariness than if you were dependent on physical activity to meet your basic needs for survival.

Remember, there were times, not too long ago, when people were actually paid to be physically active. Today, choosing to be physically active actually costs money (not to mention time).

Edmonton, Alberta

Monday, July 14, 2008

Orlistat and Kidney Stones

Orlistat is a gastrointestinal lipase inhibitor sold as a prescription drug under the brand name Xenical and is also available in some countries (including the US) as an over-the-counter (OTC) weight-loss aid under the brand name Alli.

Orlistat has been around for almost a decade and has been extensively studied. No question, when used appropriately with recommeded dietary and lifestyle changes it aids in achieving about 5% weight loss and clinically relevant improvements in cardiometabolic risk factors (high blood pressure, low HDL, high blood sugars, etc.). As with all obesity drugs, weight is generally regained when the medication is discontinued - nothing new here!

Because the action of orlistat is limited to the gut (it is not absorbed in relevant amounts), it is promoted as not having any "systemic" side effects. The main side effects are fully explained by its impact on fat digestion and are generally limited to diarrhea, oily discharge and abdominal discomfort - unpleasant for sure, but certainly not a major health concern.

There is also some interference with the absorption of fat-soluble vitamins (ADEK) but this should not be a problem with a healthy balanced diet or proper intake of vitamin supplements. There is however, also a significant impact on lipid-soluble medications (e.g. ciclosporine A) and patients on these medication may need some readjustment of the dose.

All of the above is well known, extensively studied and not really of great concern for most patients.

But here is one side effect I'd be worrying about if I belonged to the people who tend to get kidney stones - there is a distinct chance that orlistat can increase urinary oxalate excretion thereby potentially promote formation of oxalate stones - anyone who's ever experienced a kidney colic knows exactly why this is something you want to avoid.

The cause of this potential side effect is related to the simple fact that the unabsorbed fat and bile acids resulting from the use of orlistat may react with calcium in the intestinal lumen, limiting the amount of free calcium binding with oxalate and thereby raising intestinal oxalate absorption leading to hyperoxaluria, which in turn can promote formation of oxalate stones.

This rather complex-sounding but rather straightforward state of affairs was first proposed based on a marked increase in urinary oxalate excretion observed in rats given orlistat together with a high-fat diet in a study by Renato Ribeiro Ferraz and colleagues from the Universidade Federal de São Paulo published in KIDNEY INTERNATIONAL in 2004.

In 2007, Ashutosh Singh and colleagues from the University of Tennessee described the case of a female patient with chronic kidney disease, who developed acute oxalate nephropathy with the use of orlistat (Am J Kidney Dis). Urine sediment showed abundant calcium oxalate crystals and 24-hour urine oxalate concentration was significantly elevated. Kidney biopsy showed deposition of calcium oxalate crystals within the tubular lumens. A repeat biopsy one month after discontinuing orlistat no longer showed signs of oxalate and renal function slowly recovered to baseline.

Now, in this month's issue of OBESITY, Kemal Sarica and colleagues from the Memorial Hospital in Istanbul, Turkey, report the data from a study in 95 obese patients (57 men, 38 women) randomly assigned to treatment with orlistat for 6 months vs. no specific medication. In the treatment group, two-thirds of patients showed a marked increase in urinary oxalate excretion at 3 months, which largely persisted at 6 months. Although no kidney stones were noted, the authors commented that the increase in oxalate excretion would have been enough to promote oxalate stone formation in susceptible individuals.

Nothing dramatic here - unless of course you are someone who happens to be at risk for oxalosis and oxalate kidney stones.

If you are, perhaps best to avoid orlistat or at least cut down on the concomitant use of high oxalate foods like rhubarb, spinach, strawberries, chocolate, wheat bran, nuts, beets, and tea and drink plenty of water.

Edmonton, Alberta

Friday, July 11, 2008

Exhaustion Promotes Weight Gain

OK, we know stress, lack of time, low socioeconomic status, poor locus of control and poor sleep promote obesity - but here is a new one (at least for me): Vital Exhaustion.

The term Vital Exhaustion (VE) has three defining characteristics: (1) feelings of excessive fatigue and lack of energy, (2) increasing irritability, and (3) feelings of demoralization.

People often attribute these feelings to overwork, or to problems at work or in other important life areas that the person has not been able to solve, or to a real or symbolic loss. Therefore, it has been suggested that VE is a mental state at which people arrive when their resources for adapting to stress are broken down.

Now Maria Bryant and colleagues from the University of Leeds, UK in a paper just out in OBESITY, examined the relationship between VE and BMI cross-sectionally and after 3 and 6 years of follow-up among the 13,727 participants in the Atherosclerosis Risk in Communities (ARIC) study.

BMI was significantly higher among both white and African-American men and women in the highest VE quartile compared to those with no VE. Similarly, high VE at baseline was associated with higher BMI 3 and 6 years later. Baseline VE predicted future excess weight gain in white men and women, but not in African Americans.

Clearly, if this relationship is causal, identifying the factors contributing to VE and addressing them may help prevent and reduce the burden of obesity - certainly easier said than done.

Anyone who thinks we will solve the obesity crisis by handing out diet plans and chasing people around the block are kidding themselves.

Edmonton, Alberta

Thursday, July 10, 2008

How much protein is enough?

The recommended dietary allowance (RDA) is an estimate of the minimum average dietary intake level that meets the nutrient requirements of nearly all (~97%) healthy individuals.

According to this recommendation, the RDA for protein is 0.8 g/kg/d

Interestingly, as pointed out in a recent commentary by Robert Wolfe and Sharon Miller from the University of Arkansas published in the June 25 issue off JAMA, the term “recommended dietary allowance” is misleading as it is often misinterpreted as being the “optimal” rather than the “minimal” dietary requirement.

In fact, as illustrated in the commentary, if protein requirements are calculated based on a recommended proportion of energy intake [i.e. 10 to 35%], for a 70 Kg man requiring 3067 kg calories per day, 10% of energy as protein would translate into a protein intake of 0.95 g/kg/d whereas 35% of energy intake would translate to 3.3 g/kg per day. These values are obviously substantially higher than the RDA.

As blogged before, given the importance of maintaining appropriate protein intake to maintain muscle mass, strength and function, the issue of ensuring adequate protein intake during a caloric restricted diet becomes even more challenging. This means that caloric restricted diets need to at least provide a protein intake at the higher end of the Dietary Reference Intakes [DRI] or around 35% of total caloric intake and should perhaps err on the side of too high rather than too low.

The issue of maintaining appropriate protein intake is particularly important as close monitoring of body composition to detect disproportionate loss of lean body mass during weight loss is not routine part of patient monitoring during obesity treatment.

Perhaps, as recommended by Wolfe and Miller, the term “recommended dietary allowance” should be replaced by the term “minimal dietary requirement” to more accurately reflect the functional definition of RDA and avoid confusion regarding what is considered adequate protein intake.

Edmonton, Alberta

Wednesday, July 9, 2008

No Food For the Lazy!

Yesterday, newspapers reported widely about the UK conservative leader David Cameron calling on the obese, the idle, and even the poor to accept some responsibility for their plight.

According to Cameron, society has become "far too sensitive" to people's feelings, with no one prepared to say "what needs to be said." "We talk about people being 'at risk of obesity' instead of people who eat too much and take too little exercise".

Great stuff! So all fat people eat too much and are lazy - they deserve their plight! In other words, let's stop coddling them and let's certainly not bother providing them with any health services for their plight.

Perfect. Let's next stop providing services for all smokers who get heart attacks or cancer, no more trauma surgery for anyone who gets injured driving above the speed limit or, God forbid, gets run over jay walking. No more health services for anyone coming down with influenza who did not get his flu shot, no more medical freebies for people spraining their ankles at sports, and obviously definitely no more medical help with "lifestyle diseases" like diabetes, high cholesterol, hypertension, osteoporosis, osteoarthritis and back pain.

Everyone is the master of their own destiny.

Thank you Mr. Cameron for saying what needed to be said.

Anyone feeling depressed? Suck it up!

Edmonton, Alberta

Tuesday, July 8, 2008

Proconvertase Gene Linked to Obesity

As unequivocally documented by twin studies, obesity is one of the most heritable complex traits. However, so far only a handful of genes that may play a role in the common "garden variety" of obesity (i.e. not just the rare monogenic forms) have been identified .

This week, a large research team led by Philippe Froguel (Picture) that included scientists from France, Denmark, Sweden, Germany and the UK report in Nature Genetics that relatively common variants of the PCSK1 gene, which codes for the proconvertase enzyme are associated with higher BMI. This enzyme is responsible for producing fully functioning versions of hormones such as insulin and glugagon that play important roles in carbohydrate metabolism but also for melanocortin, a key regulator of satiety.

Although the identified variants of the PCSK1 gene cause only relative minor functional changes in this enzyme, the effect on the relevant hormones is quite significant.

Obviously, no single gene or variant thereof can account for all of obesity and there is no reason to believe that all obesity is the same. Rather, it is clear that the heritability of obesity must be due to the distribution of a large number of variants of numerous genes in the population.

So when do we begin using genetic testing in our obesity clinics - not for a while I am guessing, i.e. till we can actually show that specific genes also predict better (or worse) outcomes with specific treatments.

In the dark, all cats are grey.

Edmonton, Alberta

Monday, July 7, 2008

Germany Wakes up to Obesity

As elsewhere in Europe, obesity is on the rise in Germany. According to government statistics, two-thirds of all German men between the ages of 18 and 80 are overweight and almost half of all women have a weight problem. These numbers add up to about 37 million adults and 2 million children and teenagers suffering from some kind of weight related disorders.

In response, the German government has now embarked on a new obesity initiative prepared by Health Minister Ulla Schmidt in cooperation with Food, Agriculture and Consumer Protection Minister Horst Seehofer. The program's initiative is to cut diseases related to obesity drastically by the year 2020, and foresees spending 30 million euros ($46.7 million) over the next two years.

As everywhere else, in Germany too, the government recognizes that the epidemic is not only a result of poor nutritional habits and lack of exercise but also wide-ranging societal and infrastructural factors. It therefore calls on politicians, scientists, health-care providers, unions and the food industry to help educate and promote healthier lifestyle approaches. As one may guess the ideas include: education on healthy eating and physical activity, tougher standards on school food programs, better product labeling by the food industry, reduced advertising by the makers of sweets and junk food that target children, i.e. essentially the usual list of initiatives.

As everywhere else, in Germany too, the government largely ignores one major consequences of the fact that 37 Million Germans are already living with this chronic disease, namely that this also calls for an immediate need to provide improved access to evidence-based obesity treatments with expansion of the resources to do so.

As in most other countries (the UK being a remarkable exception), access to professional obesity treatment that includes behavioural therapy, anti-obesity medications and surgery remains limited to a ridiculously small number of individuals, mostly those who can afford "private" payments for these services.

As I have blogged before - promoting obesity prevention (and hoping for these to kick in) should not be an excuse to deny obesity treatments to those already affected by this condition.

Edmonton, Alberta

p.s. incidentally, my blog is now also available in German

Image Rainer Zenz

Friday, July 4, 2008

Does Metabolic Syndrome Predict Heart Disease?

Metabolic syndrome or syndrom X (recently refered to as Xyndrome) is the combination of abdominal obesity, high trigylcerides, low HDL cholesterol, high blood pressure and elevated levels of fasting blood glucose. This concept has been widely promoted as helping to clinically identify individuals at increased risk for heart disease.

While the concept appears intuitively sound (as all five components of this syndrome have been individually associated with increased cardiovascular risk), there is a continuing debate on whether the concept of this "syndrome" is any better in identifying individuals at risk for heart disease than looking at each individual risk factor on its own.

To address the issue of whether or not the "metabolic syndrome" is indeed a risk factor for heart disease, Naveed Sattar and colleagues from University of Glasgow examined the relationship between the metabolic syndrome and incident cardiovascular disease and type 2 diabetes in in 4812 non-diabetic individuals aged 70-82 years from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). They corroborated these data in a second prospective study (the British Regional Heart Study [BRHS]) of 2737 non-diabetic men aged 60-79 years. (The Lancet)

In PROSPER, metabolic syndrome was not associated with increased risk of cardiovascular disease over 3.2 years but was associated with a 4-fold increased risk of diabetes. In contrast elevated fasting glucose alone was associated with an 18-fold increased risk for diabetes.

Likewise, in BRHS, metabolic syndrome was only modestly associated with incident cardiovascular disease despite a strong association with diabetes.

Importantly, in both studies, body-mass index or waist circumference, triglyceride, and glucose cutoff points were also not associated with risk of cardiovascular disease, but all five components were associated with risk of new-onset diabetes.

The authors conclude that while metabolic syndrome and its components are associated with type 2 diabetes, they only have a weak to no association with vascular risk in elderly individuals. Their recommendation is that the clinical focus should remain on establishing optimum risk algorithms for each individual risk factor rather than lumping them together as a putative "syndrome".

Obviously, one could argue that there may still be some use for the concept of the metabolic syndrome in younger individuals, but, as discussed in this paper, the same group (and others) have also not found the metabolic syndrome to be a strong predictor of heart disease in younger individuals.

Irrespective of whether or not the concept of the metabolic syndrome is helpful, it should be remembered that obesity treatment is the only intervention that can simultaneously have beneficial effects on all five components of this syndrome. Thus, while conventional care continues to aggressively target the individual risk factors, only aggressive obesity treatment will indeed improve all features of this putative syndrome.

Unfortunately, with the exception of obesity surgery, we still lack outcome studies confirming that obesity treatment will indeed decrease cardiovascular mortality.

Remember, the assumption that losing weight (without surgery) will save lives is not based on hard evidence from randomised controlled trials. My guess is that till we have better data on this issue, physicians, payers and policy makers will continue to question the benefits of tackling obesity with the same resources and enthusiasm as for other chronic diseases.

Edmonton, Alberta

Thursday, July 3, 2008

Trendz in Cafeteria Food

Yesterday I had lunch at the Cafeteria of the Glenrose Rehabilitation Hospital just across the street from my office at the Royal Alexandra Hospital.

The cafeteria is built on Capital Health's own Healthy Choice Trendz(TM) philosophy that includes a Bistro concept that makes the healthy choice the easy choice. Not only is there no sign of a deep fryer (a rarity for North America) but one really has to look for the unhealthy stuff on the menu.

The standard meat servings are smaller and the plate comes heaped with stir fried vegetables (no oil!) and roast potatoes. Soups come in low-sodium versions, there are even low-fat biscotti, and all breads are whole-grain by default.

Finally, at the coffee outlet, you have a choice of skimmed and 2% milk - cream you have to ask for.

Yes there are some unhealthy choices like pop but the water and juices are up front - the pop you have to actually bend over to pick up.

No problem getting a healthy lunch there - of course, if you try hard, you can find the stuff that it's better to avoid - but they sure don't make it easy on you.

Obviously, Capital Health, which developed and is currently establishing the healthy Trendz concept in all of its food outlets, is not only proud of the concept but has assured me that they have even found that offering healthy choices is profitable.

Hopefully the role-out across the region and beyond will not take too long.

Edmonton, Alberta

p.s the picture is not of the actual food I got, but it certainly comes close

Wednesday, July 2, 2008

Don't Spare the Protein

To anyone trying to lose weight, avoiding the virtually obligatory reduction in lean body mass is always a challenge. Not only does "offloading" as the body gets lighter reduce the actual "weight-bearing" work resulting in loss of muscle mass, but also the fact that most dietary recommendations tend to also reduce protein intake to maintain a "balanced" diet can promote a protein catabolic state.

As skeletal muscle is a major determinant of energy expenditure, losing muscle mass eventually limits the amount of weight that can be lost at any given caloric deficit, resulting in an early plateau. Furthermore, as lost lean body mass tends to be replaced with fat during weight regain (catch-up fat), you end up with a greater fat mass than before your diet.

The importance of maintaining protein intake during diet-induced weight loss was again illustrated in a recent study by Melanie Bopp and colleagues from Wake Forest University School of Medicine, Winston-Salem, NC, published in the Journal of the American Dietetic Association.

The authors investigated the association between dietary protein intake and loss of lean mass during weight loss in postmenopausal women through a retrospective analysis of a 20-week randomized, controlled diet and exercise intervention in women aged 50 to 70 years. Weight loss was achieved by differing levels of caloric restriction and exercise. The diet-only group reduced caloric intake by 2,800 kcal/week, and the exercise groups reduced caloric intake by 2,400 kcal/week and expended approximately 400 kcal/week through aerobic exercise.

Lean mass was measured using DEXA. Average weight loss was 10.8+/-4.0 kg, with an average of 32% of total weight lost as lean mass. While protein intake averaged 0.62 g/kg body weight/day (range=0.47 to 0.8 g/kg body weight/day), participants who consumed higher amounts of dietary protein lost less lean mass. These associations remained significant after adjusting for intervention group and body size.

The authors conclude that inadequate protein intake during caloric restriction may be associated with adverse body-composition changes in postmenopausal women.

I would dare to add that the same is probably true for anyone undergoing a dietary weight loss intervention that does not maintain adequate protein intake.

Edmonton, Alberta

Tuesday, July 1, 2008

Count Those Liquid Calories!

Yesterday, the Edmonton Sun did a full-page feature on me because they find it kind of special that I ride my bike to work (guess it is special in car-loving Alberta).

Of course the article also includes the obligatory Dr. Sharma's tips which starts off with Tip #1: beware of liquid calories like in juices, pop or alcohol - at least, count them as part of your meal, as they can quickly add up.

Almost on cue, the Consumer Federation of America (CFA), in attempting to fill the void in consumer information on liquid calories, yesterday released Alcohol Facts, a side-by-side comparison of the alcohol, calorie and carbohydrate content per serving of the top 26 domestic and imported alcoholic beverage brands sold in the US.

Alcohol Facts reveals significant differences in the amount of calories and carbohydrates for beer, wine and distilled spirits both by category and by brand.

* Among spirits, calories per serving ranged from 86 calories for spiced rum to 120 calories for gin. The average (not including mixers) was 98 calories per serving;

* For wines, calories per serving ranged from 105 calories for a merlot to 125 calories for a cabernet sauvignon. The average was 118 calories per serving;

* The greatest variation in calories occurred among beers and flavored malt beverages. Light beers (5 brands) averaged 100 calories per serving, regular beers averaged 140 calories (5 brands) per serving, and the flavored malt beverages (3 brands) ranged from 190 calories per serving to 241 calories per serving; 

* Variations were greatest when analyzing carbohydrate levels. Compared to no carbohydrates in spirits, wines ranged from 0.8 grams per serving for chardonnay to 5.0 grams per serving for cabernet sauvignon. Among different beers and malt beverages, carbohydrates ranged from 3.2 grams per serving for light beer to 38 grams per serving for a flavored malt beverage.

The CFA is strong on promoting caloric labeling on alcoholic beverages, which till now only contain the alcohol in %. (to calculate the calories, you'd first have to calculate the grams alcohol per serving, multiply by 7 and then you are still missing the calories from carbs - so calculating the calories for alcoholic beverages for consumers is virtually impossible!)

From my own practice I can only confirm that it is not that unusual to find patients regularly consuming over half their caloric needs in fluids, including alcohol.

Putting calories on alcohol bottles may not stop people from drinking, but at least it allows them to count those calories in their daily allowance.

Happy Canada Day!

Edmonton, Alberta