Arya M. Sharma, MD

Regular readers will recall the accumulating evidence that maternal health and weight before and during pregnancy may have a substantial influence on the risk of excessive weight gain in their offspring, most likely resulting from epigenetic programming in utero.

A study by Mina Desai and colleagues from the University of California Los Angeles, just published in Brain Research, now suggests that intra-uterine genetic adaptation may have a substantial influence on the growth and development neurons that regulate appetite and energy homeostasis.

The researchers examined the hypothesis that a programmed impairment of neural progenitor cells (NPC) may contribute to altered hypothalamic neural pathways that control feeding behaviours in the development of low-birth-weight (LBW) offspring.

In their study, they examined hypothalamic NPCs in the brains of pups born to food restricted and unrestricted mice and showed that the LBW offspring born to the former had impaired in vivo evidence of NPC division and migration, and reduced in vitro evidence of proliferation and differentiation to neurons and astrocytes, under basal and when stimulated with the appetite-regulating hormones insulin and leptin.

These studies show that the environmental exposure of the mother can significantly affect the brain development of offspring in areas essential for appetite and energy control.

Although these findings come from animal studies, the association between adverse in utero factors, resulting in either low or too-high birth weight babies, and excess weight gain in kids, youth and adults has been accumulating in human studies.

Thus, these findings, add considerable plausibility to the postulated relationship between maternal health and fetal programming of appetite and energy regulation increasing the propensity to obesity later in life.

AMS
Edmonton, Alberta

Desai M, Li T, & Ross MG (2011). Hypothalamic neurosphere progenitor cells in low birth-weight rat newborns: Neurotrophic effects of leptin and insulin. Brain research, 1378, 29-42 PMID: 21215735

Gestational diabetes and excessive gestational weight gain have significant implications for the health of both mother and child.

Anne-Sophie Morisset and colleagues from Laval University, Quebec City, Canada, now examined the relationship between weight gain early in pregnancy and the risk for gestational diabetes, in a paper just published in the Journal of Womens Health.

The researchers examined data from medical records of women who delivered between January and December 2007 at the Laval University Medical Centre, which included 294 women (55 cases of gestational diabetes and 239 controls).

Weight gain in the first trimester was significantly higher in patients who developed gestational diabetes than in controls (3.4 vs. 1.9  kg), whereas whereas weight gain in the third trimester was significantly lower in diabetes patients compared to controls (4.1 vs. 6.3 kg).

Both prepregnancy BMI and first trimester weight gain were significant and independent predictors of diabetes suggesting that both preconception weight as well as weight gain during the first trimester may warrant greater clinical attention.

This is particularly important given the discussions and concerns about the fetal development theory of epigenetic program, which many today believe to be one of the key drivers of childhood obesity.

AMS
Edmonton, Alberta

Morisset AS, Tchernof A, Dubé MC, Veillette J, Weisnagel SJ, & Robitaille J (2011). Weight Gain Measures in Women with Gestational Diabetes Mellitus. Journal of women’s health (2002) PMID: 21332414

In my interactions with patients, I always ask them to tell me when their weight problems began and what they believe contributed to their weight gain.

Broadly speaking, there are two categories: people, who were big (or were considered big by others) as long as they can remember and those, who can often clearly pinpoint when their weight problem started. Individuals in the latter group can often recall a specific event or situation that led to their weight gain (e.g. when I miscarried, when I entered puberty, after my second child, when I moved to Canada, etc.).

After hearing hundreds of such stories, common themes emerge, which in the past have led me to make statements such as, “Many roads lead to obesity” or, “Obesity can happen to anyone - no one is immune”.

So how exactly do people with obesity tend to explain their excess weight and do men and women differ in their explanations?

This fascinating topic was now explored by Louise Smith and Lotte Holm from the University of Copenhagen, in a paper just published in the Scandinavian Journal of Public Health.

The researchers conducted extensive in-depth interviews of 20 Danish middle-aged men and women who had experienced obesity, randomly selected from a representative nationwide dietary survey.

While some of the participants had lost weight, others were weight stable. Some reported being overweight from childhood, others reported steady or sudden weight gain later in life.

Most interestingly, there were clear gender differences in the explanations offered for weight gain between men and women.

In men, the following central themes emerged: Firstly (and most commonly), men reported life-course transitions (usually from youth to adulthood), whereby they perceived education or work-related obstacles that prevented or reduced physical activity levels as most relevant. Men also frequently referred to injuries that reduced their physical activity.

Some men reported eating for comfort or due to personal problems, most often related to work, unemployment, or financial concerns - rarely to social or relationship problems.

Some men also mentioned work environments that promoted overeating (e.g. when I began work as a cook).

The stories that women told were strikingly different. Although women also presented “life-course” explanations, these were less frequently related to shifting living conditions or social obligations, but rather to transitions in the female biological cycle such as puberty, pregnancy, and menopause.

The second theme in women was related to changes in social relationships (e.g. when I met my husband, when we moved in together, etc.).

The third theme in women was overeating related to personal problems, in all cases related to intimate social relationships (e.g. I did not receive adequate love in my childhood, I was brought up in a family with an alcoholic father, etc.).

The fourth theme in women was related to the use of psychopharmaca (e.g. for depression, when I began having lithium, etc.).

As the authors point out, it is perhaps not all that surprising that women are more likely to relate the beginning of their weight problems to their biology (which is clearly far more striking and eventful in women than in men) and to problems in their intimate and personal relationships.

In contrast, men look at both life-transitions and emotional stressors more in the context of work (e.g. new job, retirement, unemployment, financial trouble) or blame injury or other circumstance for reduced activity levels.

Thus, as previous research has shown, when it comes to overeating, women typically invoke family obligations, whereas men allude to obligations outside the family.

The fact that the use of psychopharmaca came up as a distinct theme in women but not in men, may be related to the fact (as the authors suggest) that these drugs are far more commonly used in women than in men.

These gender differences are not only striking but may also have important implications for addressing obesity both in populations and in individuals.

Firstly, nowhere in this discourse of life stories, did “lack of knowledge” come up as a driver of weight gain. Thus, it is perhaps not at all surprising, that the public health strategies focussing on “educating” the public on healthy eating and activity, have thus far had virtually no impact on obesity rates.

Rather, based on their findings, the authors suggest that obesity prevention strategies need to target men and women differently and must take into account their very different life histories:

In women, obesity prevention strategies are perhaps best focussed at key times during their biological lifecycles (e.g. at puberty, around pregnancies and menopause) and emotional eating may be best dealt with by addressing and improving coping skills in personal relationships (i.e. at home, within families, etc.).

In men, obesity prevention efforts are perhaps best targeted at periods of educational or professional transition. Emotional eating in men may be best dealt with by addressing social stressors related to work and livelihood and are probably best offered in the workplace.

Certainly a lot for the public health folks to chew on.

In light of these findings I cannot but help emphasize just how important it is to engage and listen to the people who actually have the problem, which we as researchers and health professionals are trying to help solve.

This is exactly the intention of the Canadian Obesity Awareness and Control initiative for Health (COACH), which I blogged about earlier this week.

If you have not yet taken the COACH survey but would like support this initiative, please take three minutes to complete this survey now.

Click here to take survey

As always, I would love to hear from my readers as to whether or not they can relate to these findings - Copenhagen may not be as far away as we think.

AMS
Edmonton, Alberta

Hat tip to Nathalie for bringing the study to my attention.

Smith LH, & Holm L (2011). Obesity in a life-course perspective: An exploration of lay explanations of weight gain. Scandinavian journal of public health PMID: 21270139

While the growing concern about childhood overweight and obesity has spawned a wide-ranging discussion on the causes and approaches to best tackle this epidemic, evidence to support actions that will demonstrably reduce childhood obesity remain hotly debated.

In the light of this discussion, it is not only important to better understand the determinants of childhood obesity but also to examine proposed intervention strategies both in terms of feasibility and efficacy.

This exercise was undertaken by Kuhle and colleagues from the University of Alberta in a paper just published in the Canadian Journal of Public Health that examines the prevention potential of risk factors for childhood overweight.

In order to estimate the population-attributable risk for childhood overweight risk factors, the researchers examined data from a population-based survey of Grade 5 students who participated in the 2003 Children’s Lifestyle and School Performance Study in Nova Scotia, Canada. Data from this survey was linked to a provincial perinatal registry to also determine the role of maternal factors in the risk for excess weight in childhood.

Of the various “preventable” factors that were considered, including physical activity, sedentary activity, maternal smoking during pregnancy, and maternal pre-pregnancy weight, both sedentary activity (as estimated from time spent viewing TV, computers and video games or “screen time”) and maternal pre-pregnancy weight appear to offer the greatest potential for prevention.

Based on their analyses, the researchers concluded that addressing these two issues could potentially prevent approximately 40% of overweight in childhood.

Obviously, this calculation assumes that there are effective ways of actually reducing pre-pregnancy weights and the time kids spend on sedentary activities. Regular readers of these pages probably appreciate that this may not be quite as straightforward as it sounds.

On the other hand, recognizing where intervention strategies can perhaps provide the “biggest bang for the buck” is certainly a step in the right direction.

AMS
Edmonton, Alberta

Kuhle S, Allen AC, & Veugelers PJ (2010). Prevention potential of risk factors for childhood overweight. Canadian journal of public health. Revue canadienne de sante publique, 101 (5), 365-8 PMID: 21214049

Readers of these pages are by now quite familiar with the increasing evidence showing that what happens to the fetus in utero may be a key determinant of obesity risk later in life. Thus, both small-for-gestational-age and large-for-gestational-age babies appear at increased risk for becoming obese kids (and adults).

One of the important determinants of infant weight is the magnitude of maternal weight gain in pregnancy. But how strong is this relationship really?

This question was now examined by David Ludwig (Harvard) and Janet Currie (Columbia) in a paper published last month in The Lancet.

The researchers examined data from a population-based cohort study that included all known births in Michigan and New Jersey, USA, between Jan 1, 1989, and Dec 31, 2003, or a total of 513 501 women and their 1,164,750 offspring.

Using a within-subject design to reduce confounding to a minimum, they noted a strong and consistent association between pregnancy weight gain and birthweight: infants of women who gained more than 24 kg during pregnancy were almost 150 g heavier at birth than were infants of women who only gained 8-10 kg.

Women who gained more than 24 kg during pregnancy were more than twice as likely to give birth to an infant weighing more than 4000 g than women who only gained 8-10 kg.

In light of the increasing evidence that larger infants are much more likely to become overweight and obese children (and later adults), this study certainly supports the need for efforts to prevent excessive weight gain during pregnancy.

Targeting obesity prevention and treatment strategies to younger women and limiting excessive weight gain during pregnancy, may well be the single most effective way to prevent obesity in future generations.

AMS
Edmonton, Alberta

Ludwig DS, & Currie J (2010). The association between pregnancy weight gain and birthweight: a within-family comparison. Lancet, 376 (9745), 984-90 PMID: 20691469