Friday, July 18, 2014

Birth Control And Obesity

sharma-obesity-birth-control-pillAlthough obesity is a well-recognised factor for female infertility, the vast majority of women with excess weight are probably more interested in effective birth control.

That this is not as simple as it seems is evident from an article by Sheila Mody and Michelle Han from the University of California, San Diego, published in Clinical Obstetrics and Gynecaology.

The paper succinctly reviews a wide range of issues related to birth control and obesity.

To begin with, the authors points out that unintended pregnancies in obese women are often a problem simply because obese women are far less likely to use effective contraception than non-obese women. This non-use may in part be attributable to fear of weight gain, when most studies show that modern hormonal contraception is associated with almost no weight gain. The exception appears to be depot-medroxyprogesterone (DMPA), which may cause about 5 lb weight gain in the first year of use.

As for efficacy, the data show that unintended pregnancy rates among overweight women using oral contraceptives are similar or slightly higher than that among nonoverweight women. The reasons for these higher rates are not exactly clear.

Fortunately, the efficacy of intrauterine devices (IUD) appear no different between obese and non-obese women although the insertion of an IUD maybe more difficult in obese women because of poor visualization of the cervix and limited assessment of uterine position (a problem that can often be solved with the help of an ultrasound).

The paper also discusses the suitability of the vaginal vaginal contraceptive ring, which has been hypothesized to offer higher hormone levels for obese women than oral contraceptives because the hormones are absorbed directly into the vaginal mucosa and do not go through the first- pass liver metabolism.

Finally, the paper discusses issues around contraception for women who have undergone bariatric surgery (who have a particularly high rate of unintended pregnancies) as well as best practices for emergency contraception.

This is clearly information that all clinicians who counsel obese women should be aware of.

@DrSharma
Edmonton, AB

ResearchBlogging.orgMody SK, & Han M (2014). Obesity and Contraception. Clinical obstetrics and gynecology PMID: 25029338

 

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Monday, July 14, 2014

How To Prevent Gallstones During Weight Loss

GallstonesOne of the best recognised complications of weight loss – especially if this occurs too rapidly – are the development of gallstones, which can result in acute symptoms and often require surgery.

Now Caroline Stokes and colleagues from the Saarland University Medical Center, Homburg, Germany, publish a systematic review of strategies to prevent weight-loss associate gallbladder stones in Clinical Gastroenterology and Hepatology.

Their analysis includes 13 randomised-controlled trials, comprising 1836 participants undergoing weight loss through dieting (8 trials) or bariatric surgery (5 trials).

Ursodeoxycholic acid (UDCA) reduced the risk of ultrasound-verified gallstones compared with control interventions with a risk ratio of 0.33 and a number-needed-to-treat (NNT) of only 9.

They also found a significant risk reduction with high-fat weight loss diets (risk ration 0.09).

No adverse effects were noted for either intervention.

Thus, it is evident that UDCA and/or higher dietary fat content prevent the formation of gallstones during weight loss and these treatments should likely be initiated particularly in patients, who are undergoing rapid weight loss (particularly those at high risk of gallbladder stones).

@DrSharma
Edmonton, AB

ResearchBlogging.orgStokes CS, Gluud LL, Casper M, & Lammert F (2014). Ursodeoxycholic Acid and Diets Higher in Fat Prevent Gallbladder Stones During Weight Loss: A Meta-analysis of Randomized Controlled Trials. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association, 12 (7), 1090-110000 PMID: 24321208

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Tuesday, July 8, 2014

Does BMI Underestimate Adiposity in Kids?

sharma-obesity-kids-scale2Regular readers are well aware of my reservations regarding the use of BMI as a diagnostic parameter in clinical practice. After all, while BMI may tell us how big someone is, it certainly is not a good measure of how sick someone is.

But to be honest, BMI was never intended as a measure of disease – it was (at best) introduced as a surrogate measure of adiposity (fatness).

Nevertheless, supporters of BMI continue to argue that it is still a good measure of fatness and as such should remain part of standard assessment – even in kids.

Now, a paper by Javed and colleagues, published in Pediatric Obesity, examines how well BMI performs as a means to identify obesity as defined by body fatness in children and adolescents.

The authors conducted a systematic review and meta-analysis of 37 studies in over 53,000 participants assessing the diagnostic performance of BMI to detect adiposity in children up to 18 years.

While the commonly used BMI cut-offs for obesity showed showed a high specificity (0.93) to detect high adiposity, the sensitivity was much lower (0.73) – particularly in boys.

This means that kids who exceed the current BMI cut-offs are indeed very likely to have fatter bodies (for what it’s worth).

On the other hand, relying on BMI cut-offs alone will miss as many as 25% of kids whose body fat percentage exceeds current definitions of adiposity.

Thus, assuming that bod fatness or adiposity is indeed a clinically useful measure of health, the use of BMI alone will ‘underdiagnose’ adiposity in a significant proportion of kids (especially boys) who may well be at risk from excess fat.

A word of caution about fatness is certainly in order – as in adults, much depends on exactly where the fat is located (abdominal or ectopic vs. subcutaneous) and other factors (e.g. cell size, inflammation, insulin sensitivity, etc.).

Thus, even if BMI was a perfect measure of body fat, it would probably still require further examinations and tests to determine exactly whether or not this “extra” fat poses a health risk.

As in adults, a clinical staging system similar to the Edmonton Obesity Staging System may be a fat better indicator of determining which kids may need to worry about their body fat and which don’t.

@DrSharma
Edmonton, AB

Hat tip to Kristi Adamo for pointing me to this study

ResearchBlogging.orgJaved A, Jumean M, Murad MH, Okorodudu D, Kumar S, Somers VK, Sochor O, & Lopez-Jimenez F (2014). Diagnostic performance of body mass index to identify obesity as defined by body adiposity in children and adolescents: a systematic review and meta-analysis. Pediatric obesity PMID: 24961794

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Friday, June 27, 2014

Canadians Embark on Landmark Study on Managing Childhood Obesity

sharma-obesity-kids-scale2In line with  global trends, there is considerable concern in Canada on the rising prevalence of childhood obesity.

While much work continues to focus on preventing childhood obesity, far less is known about managing it.

Now, a virtual who-is-who of pediatric obesity researchers and clinicians from across Canada have embarked on a creating the CANadian Pediatric Weight Management Registry (CANPWR), the protocol of which appears in BMC Pediatrics.

CANPWR has three primary aims:

1. To document changes in anthropometric, lifestyle, behavioural, and obesity-related co-morbidities in children enrolled in Canadian pediatric weight management programs over a three-year period;

2. To characterize the individual-, family-, and program-level determinants of change in anthropometric and obesity-related co-morbidities;

3. To examine the individual-, family-, and program-level determinants of program attrition.

This prospective cohort, multi-centre study will include 1,600 children (2 – 17 years old with a BMI >=85th percentile) enrolled in eight Canadian pediatric weight management centres.

Data collection will occur at presentation and 6-, 12-, 24-, and 36-months follow-up.

Although the primary study outcomes are BMI z-score and change in BMI z-score over time a number of secondary outcomes including other anthropometric (e.g., height, waist circumference,), cardiometabolic (e.g., blood pressure, lipid profile, glycemia), lifestyle (e.g., dietary intake, physical activity, sedentary activity), and psychosocial (e.g., health-related quality of life) variables will also be assessed.

The researchers will also examine potential determinants of change and program attrition including individual-, family-, and program-level variables.

I am certain that the findings will be of considerable interest not just in terms of helping us better understand exactly how childhood obesity is being effectively managed in Canada (or not) but also provide important insights for planning future obesity management services for kids with overweight and obesity.

@DrSharma
Vancouver, BC

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Friday, June 20, 2014

Your Body Thinks Obesity Is A Disease

sharma-obesity-adipose-tissue-macrophageYesterday, the 4th National Obesity Student Summit (#COSM2014) featured a debate on the issue of whether or not obesity should be considered a disease.

Personally, I am not a friend of such “debates”, as the proponents are forced to take rather one-sided positions that may not reflect their own more balanced and nuanced opinions.

Nevertheless, the four participants in this “structured” debate, Drs. Sharon Kirkpatrick and Samantha Meyer on the “con” team and Drs. John Mielke and Russell Tupling on the “pro” team (all from the University of Waterloo) valiantly defended their assigned positions.

While the arguments on the “con” side suggested that “medicalising” obesity would detract attention from a greater focus prevention while cementing the status quo and feeding into the arms of the medical-industrial complex, the “pro” side argued for better access to treatments (which should not hinder efforts at prevention).

But a most interesting view on this was presented by Tupling, who suggested that we only have to look as far as the body’s own response to excess body fat (specifically visceral fat) to determine whether or not obesity is a disease.

As he pointed out, the body’s own immunological pro-inflammatory response to excess body fat, a generic biological response that the body uses to deal with other “diseases” (whether acute or chronic) should establish that the body clearly views this condition as a disease.

Of course, as readers are well aware, this may not always be the case – in fact, the state of “healthy obesity” is characterized by this lack of immunological response both locally within the fat tissue as well as systemically.

Obviously, it will be of interest to figure out why some bodies respond to obesity as a disease and others don’t – but from this perspective, the vast majority of people with excess weight are in a “diseased” state – at least if you asked their bodies.

While this is a very biological argument for the case – it is indeed a very insightful one: it is not the existence of excess body fat that defines the “disease” rather, how the body responds to this “excess” is what makes you sick.

As readers, are well aware, there are several other arguments (including ethical and utilitarian considerations) that favour the growing consensus on viewing obesity as a disease.

Of course,  calling obesity a disease should not detract us from prevention efforts, but, as I often point out, just because be treat diabetes or cancer as diseases, does not mean that we do not make efforts to prevent them.

If calling obesity a disease increases resources towards better dealing with this problem and helps take away some of the shame and blame – so be it.

@DrSharma
Waterloo, Ontario

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In The News

Diabetics in most need of bariatric surgery, university study finds

Oct. 18, 2013 – Ottawa Citizen: "Encouraging more men to consider bariatric surgery is also important, since it's the best treatment and can stop diabetic patients from needing insulin, said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta." Read article

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