Monday, December 1, 2014

Are Sedentary Moms Promoting Childhood Obesity?

Edward Archer, PhD, University of Alabama Birmingham

Edward Archer, PhD, University of Alabama Birmingham

Last week, Edward Archer from the University of Alabama at Birmingham (UAB), published a paper in the Mayo Clinic Proceedings (to much media fanfare), suggesting that the primary driver of childhood obesity is the shifting of nutrient energy to fetal adipose tissue as a result of increased maternal energy availability paired with decreased maternal energy expenditure, resulting in fetal pancreatic b-cell and adipocyte hyperplasia – a theory, which Edwards labels the “maternal resource hypothesis”.

The primary process for these changes, as readers of these pages will have read before, is through epigenetic modification of DNA, which, together with other non-genetic modes of transmission including learned behaviours and environmental exposures (socioenvironmental evolution), leads to “phenotypic evolution”, which Edward describes as,

“…a unidirectional, progressive alteration in ontogeny that is propagated over multiple successive generations and may be quantified as the change over time in the population mean for the trait under examination (eg, height and obesity).”

Since the beginning of the 20th century, socioevironmental factors have significantly altered the energy balance equation for humans

“Socioenvironmental evolution has altered the evolution of human energy metabolism by inducing substantial decrements in EE imposed by daily life while improving both the quality and the quantity of nutrient-energy availability.”

“For example, as thermoneutral environments became ubiquitous, the energy cost of thermoregulation declined, and improved sanitation (eg, clean water and safer food) and vaccinations decreased the energy cost of supporting parasites (eg, fleas) and resisting pathogens (eg, communicable diseases and diarrheal infections).”

Over the past century, these developments have led to profound phenotypic changes including,

“progressive and cumulative increases in height, body stature and mass, birthweight, organ mass, head circumference, fat mass/adiposity as well as decreases in the age at which adolescents attain sexual maturity…”

Archer goes on to describe some of the many factors that may have changed in the past century, whereby, he singles out sedentariness as one of the key drivers of these developments (not surprising given Archer’s background in exercise science).

Thus, although one could perhaps make very similar arguments for any number of factor that may have changed in the past century to, in turn, affect insulin resistance and ultimately energy partitioning (change in diet, sleep deprivation, increasing maternal age, endocrine disruptors, antibiotic use, gut microbiota, medication use and many other factors I ca think of), Archer chooses to elevate sedentariness to being the main culprit.

While this may or may not be the full story, it does not change the thrust of the paper, which implies that we need to look for the key drivers of childhood obesity in the changes to the maternal-fetal (and early childhood) environment that have put us on this self-perpetuating unidirectional cycle of phenotypic evolution.

Ergo, the solution lies in focussing on the health behaviours (again, Archer emphasizes the role of physical activity) of moms.

While Archer largely focusses on maternal transmission, we should perhaps not forget that there is now some also evidence implicating a role for epigenetic modification and intergenerational transmission through paternal DNA – yes, dads are getting older and more sedentary too (not to mention fatter).

I do however agree with Edward, that this line of thinking may well have important implications for how we approach this epidemic.

For one,

“…the acknowledgment that obesity is the result of non-genetic evolutionary forces and not gluttony and sloth may help to alter the moralizing and demoralizing social and scientific discourse that pervades both public and clinical settings.”

Secondly,

“Future research may be most productive if funding is directed away from naive examinations of energy balance per se and redirected to investigations of interventions that alter the competitive strategies of various tissues.”

Thirdly,

“From the standpoint of the clinician, accurate patient phenotyping (inclusive of family obstetric history and metabolic profiling) may allow the targeting of women most likely to be a part of populations that have evolved beyond the metabolic tipping point and therefore require significant preconception intervention.”

While none of this may be easier or more feasible than other current efforts, they may well point us in a different direction than conventional theories about what is driving childhood obesity.

@DrSharma
Calgary, AB

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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

  • Notification of abstract review: January 8, 2015
  • Call for late breaking abstracts open: Jan 12-30, 2015
  • Notification of late breaking abstracts and handouts and slides due : Feb 27, 2015
  • Early registration deadline: March 3, 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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Wednesday, July 30, 2014

Prebiotic Fibre Alters Mother Milk and Offspring Gut Bacteria in Rats

sharma-obesity-suckling-rat1With all the attention to the role of gut microbiota and the ongoing debate as to the role of breast feeding in obesity prevention, a study by Raylene Reimer and colleagues from the University of Calgary adds an interesting spin.

Their study, now published in OBESITY shows that feeding female rat a diet high in prebiotic fibre (21.6% wt/wt) throughout pregnancy and lactation, compared to a control or high-protien (40% wt/wt) diet, results in a lower oligosaccharide content of the milk with a higher content of bifidobacteria in the offspring.

Although this did not lead to any marked differences in body composition or other metabolic parameters, the study proves the point that (at least in rats) maternal diet can affect the composition of gut bacteria in the offspring (which may or may not have metabolic benefits).

There is no reason to believe that in humans maternal nutrition may well impart a similar influence via breast feeding on the microbiota of infants.

This certainly sounds like a promising field for future research.

@DrSharma
Edmonton, AB

ResearchBlogging.orgHallam MC, Barile D, Meyrand M, German JB, & Reimer RA (2014). Maternal high protein or prebiotic fiber diets affect maternal milk composition and gut microbiota in rat dams and their offspring. Obesity (Silver Spring, Md.) PMID: 25056822

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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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