Dr. Sharma's Obesity Notes

Regular readers of these pages are well aware of the importance of the adverse effects that environmental factors during fetal development can have on the subsequent health risks of the offspring.

This is again documented in a study in rats by Emily Hayes and colleagues from McMaster University, Hamilton, Ontario, published in the latest issue of PLoS One.

In their experiments, they compared the fetal development and pregnancy outcomes in female Sprague Dawley rats raised either on a high fat diet (HF – 45% of calories from fat) or a control diet (CON – 16% of calories from fat).

Prior to pregnancy HF-fed dams had significant increases in body fat, serum leptin and triglycerides.

In addition, the HF-fed dams exhibited altered vascular development in the placenta, as well as increased hypoxia as well as a more than 3-fold increase in fetal death and decreased neonatal survival.

As the authors surmise, altered placental vasculature in animals raised on a high-fat diet may result in reduced oxygenation of the fetal tissues contributing to premature demise and poor neonatal survival.

Certainly in humans, increased maternal obesity and weight gain are associated with a significantly increased risk to both the mother and infant, an issue that I have previously discussed.

The fact that such problems can be reproduced in experimental animal models certainly points to important biological consequences of nutrition and weight gain before and during gestation that can have important consequences for the infants.

AMS
Vancouver, BC

Hayes EK, Lechowicz A, Petrik JJ, Storozhuk Y, Paez-Parent S, Dai Q, Samjoo IA, Mansell M, Gruslin A, Holloway AC, & Raha S (2012). Adverse fetal and neonatal outcomes associated with a life-long high fat diet: role of altered development of the placental vasculature. PloS one, 7 (3) PMID: 22442686

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There are good reasons to believe that for a significant number of people, the foundations of adult obesity may well be established in early childhood or even in utero.

This topic is the focus of an extensive review by Tristin Brisbois and colleagues from the University of Alberta, just published in OBESITY REVIEWS.

In their paper, the researchers screen the literature on data supporting a role for a wide range of factors in early childhood (≤5 years of age) that potentially predict the development of obesity in adulthood.

Factors of interest included exposures/insults in the prenatal period, infancy and early childhood, as well as other socio-demographic variables such as socioeconomic status (SES) or birth place that could impact all three time periods.

Their review of over 8,000 citations, resulted in relevant 135 studies, which reported a total of 42 variables as being associated with obesity in adulthood.

Of these, however, only seven variables made the cut as potential early markers of obesity.

These included maternal smoking and maternal weight gain during pregnancy, maternal body mass index, childhood growth patterns (early rapid growth and early adiposity rebound), childhood obesity and father’s employment (a proxy measure for SES in many studies).

Notably, neither early childhood nutrition or physical activity were identified as possible predictors.

Although such association studies alone by no means imply causality, the identified variables are nevertheless worth considering as reasonable targets in the development of health promotion programmes to reduce the risk of adult obesity. Clearly, the feasibility and effectiveness of such measures remains to be demonstrated.

AMS
Dallas, TX

Brisbois TD, Farmer AP, & McCargar LJ (2011). Early markers of adult obesity: a review. Obesity reviews : an official journal of the International Association for the Study of Obesity PMID: 22171945

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Regular readers should by now be quite familiar with the accumulating data suggesting that your risk for future development of obesity, diabetes, and possibly other metabolic diseases, may begin in the womb.

This topic is nicely reviewed in a paper by Marie-Claude Battista and colleagues from the University of Sherbrooke, Quebec, published in Experimental Diabetes Research.

In this paper, the authors not only discuss the relationship between maternal obesity and pregnancy risk (for both mother and child) but also discuss the complex factors that link excess weight to gestational diabetes.

They then extensively review the animal data that shows how intra-uterine epigenetic modifications can lead to a (permanent) metabolic adaptation that substantially increases the risk for obesity and diabetes in the offspring.

Finally, they critically discuss the emerging human data demonstrating the impact of lifestyle and bariatric surgery on both maternal and fetal health and the ability of these interventions to possibly break the vicious circle that perpetuates the transmission of obesity and metabolic conditions to the next generations

As the authors conclude:

“Fetal programming of metabolic function induced by obesity and GDM may have intergenerational effect and thus, perpetuate the burden of such conditions. Mechanisms by which reprogramming of fetal function might occur is directly through maternal metabolic and hormonal effects, epigenetic alterations or impaired placental function. Periconceptional weight loss interventions have demonstrated their ability to reverse the impacts of maternal obesity and GDM on the child and are of great importance for the prevention of future cardiometabolic risks in the offspring, and may thus be the best approach to break the vicious circle of intergenerational propagation of obesity and diabetes.”

They, however also caution that:

“…the nature and the timing of intervention should be carefully considered because it could also by itself induce organ reprogramming and potential long-term effect on the offspring.”

Not an easy topic (and certainly not an easy read) given the complexity of the emerging molecular, metabolic and genetic animal and human data on this issue.

However, certainly a topic that cannot be ignored in any discussion about finding solutions to the obesity epidemic.

AMS
Leipzig, Germany

Battista MC, Hivert MF, Duval K, & Baillargeon JP (2011). Intergenerational cycle of obesity and diabetes: how can we reduce the burdens of these conditions on the health of future generations? Experimental diabetes research, 2011 PMID: 22110473

The development of childhood obesity is complex and complicated. While it is difficult to point to one thing that accounts for childhood obesity (which makes it very similar to adult obesity), there are also no simple solutions.

Nevertheless, it is certainly important to understand if there are indeed factors that are associated with the increased risk for childhood obesity – especially risk factors that can potentially be ameliorated.

This was the subject of a paper by Sylvana Cote and colleagues from the University of Montreal, just published in the Archives of Pediatric and Adolescent Medicine.

The researchers studied the developmental trajectories of BMI in early childhood in an 8-year longitudinal study consisting of a representative sample of over 2000 children selected through birth registries for the Quebec Longitudinal Study of Child Development.

Three trajectories of BMI were identified: low-stable (54.5% of children), moderate (41.0%), and high-rising (4.5%).

The high-rising group, characterized by an increasing average BMI, which exceeded international cutoff values for obesity by age 8 years, was associated with two maternal risk factors: maternal BMI (with a 6-fold higher odds ration if the mother was herself obese) and maternal smoking during pregnancy (odds ration 2.28).

If these risk factors are indeed causally linked to childhood obesity (and not just surrogates for other aspects of maternal or family behaviour), then they may be amenable to intervention. Clearly, not smoking during pregnancy should by now be something that everyone should realize bears risks for both mother and offspring (and not just risk for obesity).

How to better manage weight before and during pregnancy will likely prove to ba a far greater challenge.

However, as the authors point out:

“Children continuing on an elevated BMI trajectory leading to obesity in middle childhood can be distinguished from children on a normative BMI trajectory as early as age 3.5 years. Important and preventable risk factors for childhood obesity are in place before birth.”

This means that the most effective approaches to preventing childhood obesity may well precede the birth of the child – once born, not dissimilar to managing adult obesity, all interventions are likely to be palliative.

AMS
Edmonton, Alberta

Pryor LE, Tremblay RE, Boivin M, Touchette E, Dubois L, Genolini C, Liu X, Falissard B, & Côté SM (2011). Developmental trajectories of body mass index in early childhood and their risk factors: an 8-year longitudinal study. Archives of pediatrics & adolescent medicine, 165 (10), 906-12 PMID: 21969392

As not everyone may have a chance during the week to read every post, here’s a roundup of last week’s posts:

• Will Losing Weight Make You Fat?
• Is It Time To Abandon The Notion of Personal Choice In Dietary Counseling?
• Bariatric Surgery Reduces Response to Food Cues?
• Gastric Bypass Reduces Appetite for Fat?
• Stretching Beats Walking to Prevent Complictions of Pregnancy?

Have a great Sunday! (or what’s left of it)

AMS
Edmonton, Alberta

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