Wednesday, October 8, 2014

Can Education Offset The Genetic Risk For Obesity?

sharma-obesity-dna_molecule9Obesity is a highly heritable condition with considerable penetrance, especially in our obesogenic enviroment.

However, as I have pointed out before, having a genetic predisposition for obesity (like having a genetic predisposition for other diseases such as diabetes or high blood pressure) does not mean your fate is chiseled in stone. Lifestyle changes can significantly reduce the risk, but those with a stronger genetic predisposition will have to work a lot harder at not gaining weight than those who are naturally slender.

That said, a new study by Liu and colleagues from Harvard University, published in Social Science & Medicine, shows that better education may offset a substantial proportion of the genetic risk for obesity and/or diabetes.

The researchers created genetic risk scores for obesity and diabetes based on single nucleotide polymorphism (SNPs) confirmed as genome-wide significant predictors for BMI (29 SNPs) and diabetes risk (39 SNPs) in over 8000 participants in the Health and Retirement Study.

Linear regression models with years of schooling indicate that the effect of genetic risk on both HbA1c and BMI was smaller among people with more years of schooling and larger among those with less than a high school (HS) degree compared to HS degree-holders.

As one may expect, estimates from the quantile regression models consistently indicated stronger associations for years of schooling and genetic risk scores at the higher end of the outcome distribution, where individuals are at actual risk for diabetes and obesity.

In other words, the greater the genetic risk for diabetes or obesity, the greater the positive impact of finishing high-school or college.

In contrast, having less than a high-school education augmented the genetic risk for these conditions.

From these findings the authors conclude that,

“Our findings provide some support for the social trigger model, which speculates that the social environment can attenuate or exacerbate inherent genetic risks. Furthermore, it suggests social stratification may shape how genetic vulnerability is expressed. Social hierarchies based on socioeconomic status determine the health status of individuals. According to fundamental cause theory, policies and interventions must address social factors directly to have a population-level impact on disease risk . Our results show how education, a fundamental cause of health and disease, can serve as a valuable resource that offsets even innate biological risk. Education increases an individual’s ability to adapt, modify, and use surrounding resources. As such, polices that reduce disparities in education may help offset underlying genetic risk.”

This study strongly supports my view that one cannot (and should not) ignore genetic risk when studying the effect of environmental or behavioural factors in populations or individuals. Indeed, the greatest benefit of these interventions clearly appear to be found in those with the highest genetic risk.

@DrSharma
Ottawa, ON

ResearchBlogging.orgLiu SY, Walter S, Marden J, Rehkopf DH, Kubzansky LD, Nguyen T, & Glymour MM (2014). Genetic vulnerability to diabetes and obesity: Does education offset the risk? Social science & medicine (1982) PMID: 25245452

 

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Tuesday, October 7, 2014

The Freshmen 15 Are Neither 15 Nor Limited to Freshmen

sharma-obesity-black-studentsAccording to popular belief, the first year of college can be associated with a 15 pound weight gain – often referred to as “the freshman 15″.

Now, a study by Micheal Fedewa and colleagues from the University of Georgia, look at the weight trajectory in college studies in a paper published in the American Journal of Preventive Medicine.

Their systematic review and meta-analysis includes 49 studies evaluating the effect of the first year of college (and beyond) on the dependent body weight and or %body fat.

While the researchers found a statistically significant change in body weight among students, the average weight gain was a rather modest 1.6 kg during a typical 4-year college career. Interestingly, this finding is similar to previous estimates suggesting average increases ranging from 1.1. to 2.1 kg in the first year of college.

Thus, the actual average weight gain comes nowhere close to the notorious “15″.

Also, the authors found that most of the weight gain is progressive and continues throughout college – there is little evidence that most of the weight gained (if any) happens in the first year.

Thus, despite individual anecdotal experiences of weight gain, that may sometimes approach or even exceed 15 lbs, there is little scientific basis or reason for concern about the freshman 15.

Or, as the authors put it,

These results suggest that the “Freshman 15” may not pose a significant risk to students’ health, but unhealthy behaviors throughout college may lead to unfavorable changes in body weight, as weight change does not appear to stabilize as previously reported.

Perhaps it is time to put this idea to rest and move on to study issues that may be more important than this.

@DrSharma
Guelph, ON

ResearchBlogging.orgFedewa MV, Das BM, Evans EM, & Dishman RK (2014). Change in Weight and Adiposity in College Students: A Systematic Review and Meta-Analysis. American journal of preventive medicine PMID: 25241201

 

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Thursday, August 28, 2014

Call For Abstracts: Canadian Obesity Summit, Toronto, April 28-May 2, 2015

COS2015 toronto callBuilding on the resounding success of Kananaskis, Montreal and Vancouver, the biennial Canadian Obesity Summit is now setting its sights on Toronto.

If you have a professional interest in obesity, it’s your #1 destination for learning, sharing and networking with experts from across Canada around the world.

In 2015, the Canadian Obesity Network (CON-RCO) and the Canadian Association of Bariatric Physicians and Surgeons (CABPS) are combining resources to hold their scientific meetings under one roof.

The 4th Canadian Obesity Summit (#COS2015) will provide the latest information on obesity research, prevention and management to scientists, health care practitioners, policy makers, partner organizations and industry stakeholders working to reduce the social, mental and physical burden of obesity on Canadians.

The COS 2015 program will include plenary presentations, original scientific oral and poster presentations, interactive workshops and a large exhibit hall. Most importantly, COS 2015 will provide ample opportunity for networking and knowledge exchange for anyone with a professional interest in this field.

Abstract submission is now open – click here

Key Dates

  • Abstract submission deadline: October 23, 2014
  • Notification of abstract review: January 8, 2014
  • Early registration deadline: March 5, 2015

For exhibitor and sponsorship information – click here

To join the Canadian Obesity Network – click here

I look forward to seeing you in Toronto next year!

@DrSharma
Montreal, QC

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Friday, August 1, 2014

The 5As of Healthy Pregnancy Weight Gain

5AsPregnancy_PractitionerGuide_rf-final_Page_01Yesterday, the Canadian Obesity Network released the 5As of Healthy Pregnancy Weight Gain.

This follows the release of the 5As of Obesity Management (adults) and the 5As of Pediatric Weight Management.

The 5As of Health Pregnancy Weight Gain, was developed by a working group of nurses, midwives, primary care physicians, obstetricians, researchers and policy makers convened by the Network.

It is based on the best available evidence on this topic and is intended to help primary care practitioners discuss and manage gestational weight with their patients.

The 5As of Healthy Pregnancy Weight Gain is based on the following 5 key principles:

  • Discussion about gestational weight gain should occur with every pregnant women and with every woman planning a pregnancy.

  • Achieving healthy gestational weight gain is about improving the health and well-being of both mothers and babies.

  • Early action means addressing root causes and removing roadblocks.

  • Pregnancy related health beliefs can be powerful influences on weight gain in pregnancy.

  • Achieving goals is different for every woman.

The 5As of Health Pregnancy Weight Gain can be downloaded here – pdfppt

@DrSharma
Edmonton, AB

p.s. if you did not receive the Obesity Network Newsletter with this announcement due to Canada’s new anti-spam legislation, please click here.

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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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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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