Endocrine Society Issues Scientific Statement on Endocrine Disruptors

October 10th, 2015 No comments »

The Endocrine Society has released a new a new statement on the role of endocrine disruptors in the development of obesity and other conditions. The  American Chemical Society challenges the Endocrine Society’s  report.

 

Maternal Employment and Childhood Obesity

August 24th, 2012 No comments »

Of the putative causes of obesity, one of the strongest and most consistent is maternal obesity. But maternal employment has also been implicated in a number of studies over the last few years. While not proving causation, the dramatic increase in childhood obesity since the 1970’s, coincides with an equally dramatic rise in female participation in the workforce who had children under the age of 18. This rate rose from 47.4% to 71.2%.

Are these two phenomenon related? It’s a good question. Putting two graphs next to each other doesn’t prove one affected the other. Recent studies have shows an increased likelihood that children of working mothers are more likely to be overweight than those of non-working mothers. A systemic review of OECD countries found evidence indicating the working mothers were somewhat more likely to have overweight children. PubMed: Maternal Employment Childhood Health Effects in OECD countries. A large study in the United Kingdom found that any maternal employment after birth contributed to the likelihood the child would be overweight. PubMed: Maternal Employment and early childhood obesity UK Millenium Study.

Moms are not likely to be surprised that the evidence shows that Dad’s employment or hours worked do not correlate to a child overweight, presumably because they spend less time in cooking, food preparation, and child care to begin with.

But the question still remained, does maternal employment result in less time spent in activities directly related to a child’s diet and physical activity or a reduction in other activities. So John Cawly and Feng Liu undertook to research this question, utilizing an extensive database, the American Time Use Study (ATUS).

They found that, on average, working mothers spent 277 minutes a day with children; 410 minutes for non-working mothers. Working mothers were less likely to spend any time grocery shopping, cooking, eating with children, child care and supervising children. Among women who spent any time in these activities, the average number of minutes spent was consistently lower for working than for-non-working mothers. According to the authors, “The one exception to this general pattern is that working mothers are significantly more likely to report spending any time purchasing prepared food.” Roughly 20% of both working and non-working women with children spend 0 minutes with children a day.

More specifically, 8 hours of employment is associated with women spending 7 fewer minutes grocery shopping, 23 fewer minutes cooking, 18 fewer minutes eating with children, 14 minutes fewer minutes playing with children, 51 fewer minutes caring for children, and, 5 fewer minutes supervising children. The time deficits are roughly twice as large for women with a husband or partner than for single mothers. There was no significant difference in the time spent with children by husbands whose spouse worked or did not work. Overall, fathers appear to offset less than 15% of the decrease in time that working mothers spend with their children. Even non-working men pick up only about 1/3 of the slack.

Other research in this field indicate that children of working mothers have fewer formal  meals, more food consumed grazing, more prepared foods, more time spent watching television, and more time unsupervised.

Moms are not having a picnic either. The Cawley study found that, compared to non-working mothers, working mothers spent 48 fewer minutes per day watching TV, 31 fewer minutes sleeping, 17 fewer minutes at leisure and 16 fewer minutes socializing.

As I write this, the airwaves have political ads calling for tougher restrictions on welfare payments (which go to mothers with children), specifically more rigorous work requirements. This study may indicate that there are long term consequences for such policies in terms of maternal and child health. Other policies, including those affecting food labeling and school physical activity should be re-evaluated.

Back in the 1970s, there was a lot of debate over whether mothers should work at all. This was seen as some discretionary. We are a long way away from that time. For the vast majority of working mothers, have the additional income is essential to the whole family survival.

Just a word about the American Time Use Study: This database, maintained by the Department of Labor, Bureau of Labor Statistics (http://www.bls.gov/tus/) is, in my opinion, underutilized in obesity. Predictably, we hear recommendations that people should just change their lifestyle, spend more time, like 30-60 minutes a day in physical activity, more time buying fresh foods, cooking wholesome foods, turning off the TV to do some activity, etc….Well, the ATUS provides some average time usage by adults. For weekdays: Personal care activity 9.24 hours, eating and drinking 1.19 hours, household activities 1.63 hours,  purchasing goods and services, .69 hours, caring for household members .54, comparing for non-household members .20 hours, working and work related activities 4.49 hours, educational activities .60 hours, organizational, civic and religious activities 0.25 hours, leisure and sports 4.73, telephone calls, email, .16 hours. The point is, when asking people to make changes in their diets and physical activity, we have to ask “where is this time going to come from?” It has come from other activities? Taking care of Grandma? Volunteering at church? What? Just giving ‘good advice’ is not enough when so many Americans are living such stressful lives when free time is in short supply, especially for working moms.

Read Cawley and Liu’s research at PubMed:Maternal Employment and Childhood Obesity

Illustration from www.itsnitelife.com.

Is Obesity Jumping Species?

June 11th, 2012 No comments »

The Sunday Review of the New York Times had a fascinating piece “Our Animal Natures” by Barbara Natterson-Horowitz and Kathryn Bowers. They have an upcoming book, “What Animals Can Teach Us About Health and the Science of Healing.” They discuss how animals have many of the same diseases as humans, including cancer, addiction and cutting or self-harm. They do discuss the increase in body weight among animals. They note that animals in the wild often have cycles of gaining and losing weight. But when there is an abundance of food and access to it, weight gain will follow. This applies not only to household pets but to wild animals as well. They state, “Remarkably, it is the landscape around an animal that determines whether its weight stays steady or rises.” They speculate that it may be a interruption in circadian rhythms caused by light pollution which has brightened our planet. Or, gut microbes. NYT: Our Animal Natures

One thing their excerpt did not address was whether the increase in human obesity was also seen in animal obesity.  YC Klimentidis et al did address this in an article published in the Proceedings,Biological Science of the Royal Society last June. They examined samples consisting of over 20,000 animals from 24 populations (12 divided separately into males and females) representing 8 species living with or around human populations in industrialized societies. In all populations, the trend of body weight over time was increasing.      They calculate the probability of all trends being in the same direction by chance is 1.2 x 10-7 . They found the average mid-life body weights have risen among primates and rodents living in research colonies as among feral rodents and domestic dogs and cats. The authors conclude, “The consistency of these findings among animals living in varying environments, suggests the intriguing possibility that the aetiology of increasing body weight may involve several as-of-yet unidentified and/or poorly understood factors (e.g. viral pathogens, epigenetic factors). PubMed: Canaries in the coal mine: a cross-species analysis of the plurality of obesity epidemics

This phenomenon has implications beyond the obesity epidemic. Researchers at the National Institutes of Health have observed that many standard control rats and mice used in biomedical research are sedentary, obese, glucose intolerant and on a trajectory to premature death. This, they state, may confound data interpretation and outcomes of human studies. Fundamental aspects of cellular physiology, vulnerability to oxidative stress, inflammation and associated diseases are affected by changes in dietary intake and expenditure. PubMed: “Control” laboratory rodents ‘metabolically dead’

 

Doubts about food deserts don’t deter head of HHS

June 10th, 2012 No comments »

The June 10th Washington Post has an insightful article on the federally-funded food desert initiative in Philadelphia. The article describes how an hypothesis (lack of access to healthy foods leads to eating unhealthy foods which leads to obesity) becomes a large experiment before research is done to determine if it is going to work. WaPo: Will Philadepphia’s experiment in eradicating food deserts

Last month, at the Weight of the Nation conference, Department of Health and Human Services Secretary Kathleen Sebelius took the hypothesis one step further elevating food deserts into a cause of obesity. She said, “Obesity can be caused by any combination of factors.  For some it’s an addiction like smoking.  For others it’s a lack of fresh fruits or vegetables near their home. “ This is pretty sloppy work for a conference so highly organized by the CDC and HHS. An addiction? Still being researched I believe. People are looking at whether certain foods may be “addictive” not whether excess adipose tissue itself is addictive. When a national health leader elevates putative causes like addiction and food deserts to actual causes, a disservice is done and real progress is delayed.

 

Does Air Pollution Cause Obesity?

May 19th, 2012 No comments »

An interesting new study is out showing a link between pregnant mothers exposure to common air pollutants and the development of their child. Read more…

Air Pollutants Linked to Childhood Obesity

May 19th, 2012 No comments »

Exposure to air pollution while in the womb may contribute to childhood obesity, according to a study just published in the American Journal of Epidemiology by Andrew Rundle. Polycyclic aromatic hydrocarbons (PAHs) are common air pollutants caused by burning coal, oil, gas and cigarette smoke.

The study followed 700 pregnant women in New York City who were African-American or Dominican and lived in relatively poor areas of the city. Pregnant women with high exposures had children who were 1.8 times more likely to be obese at 5 years of age and 2.3 times more likely to be obese at 7 years than children with lower levels of exposure. PubMed: Air pollutants and Obesity

New Insight on Gene-Environment Interaction

July 9th, 2011 No comments »

For many people, understanding obesity is a pretty straightforward proposition. Eat more you gain weight. Eat less you lose weight. The laws of thermodynamics. Energy in v. Energy out. End of story. Alas, we know it is not that simple. For one thing, we know that obesity is highly inheritable. For another, we know that changes in the environment can produce rapid changes in the prevalence of obesity in the population. But, while finding many genes and their variations (called alleles) have been identified, they account for only about 2% of the total genetic variation in BMI. Skeptics doubt a genetic explanation arguing that the gene pool cannot change as quickly as the current changes in obesity. (These folks have tended to see the obesity epidemic as a 75 year phenomenon. But see the book review on The Changing Body, for how long this change has been going on..around 350 years.)  On the other hand, the environmental approach has raised the question, “If the environment is so prone to creating obesity, why isn’t everyone obese?” This line of doubt is reinforced by high variations in obesity in small geographic areas.

So now Danish researchers have use the Danish Twin Registry to try to explain the interaction of genes and the environment. The Danish Twin Registry contains information on virtually all twins born in Denmark since 1870. Two groups were surveyed. What they found was that the environment may modify the genetic expression related to obesity. This environmental effect grows stronger, but only for some individuals and not for others. They estimate that there is a 33.3% increase in the expression of adiposity-related genes associated with a 10% increase in the prevalence of obesity. They conclude that the genetic architecture of obesity should not be considered independent from the environmental context. PLoS ONE: Increased Genetic Variance of BMI with a Higher Prevalence of Obesity

Environment

September 26th, 2009 No comments »

The modern built environment may send cues to individuals for eating. Obesity and the built environment: changes in envi…[Int J Obes (Lond). 2008] – PubMed Result

The local number of fast food outlets is associated with higher BMI, as is car ownership. Body mass index, neighborhood fast food and restau…[J Urban Health. 2009] – PubMed Result

Better access to supermarkets and less access to convenience stores are associated with higher BMI levels. Neighborhood environments: disparities in access t…[Am J Prev Med. 2009] – PubMed Result

Research Activities, April 2009: Child/Adolescent Health: Boosting and preserving green spaces in urban neighborhoods may help reduce childhood obesity

Local food environments, obesity and diabetes: http://www.healthpolicy.ucla.edu/pubs/files/Designed_for_Disease_050108.pdf

Journal of Public Health Policy – New Recreational Facilities for the Young and the Old in Los Angeles: Policy and Programming Implications

Journal of Public Health Policy – Disparities in Urban Neighborhood Conditions: Evidence from GIS Measures and Field Observation in New York City

Journal of Public Health Policy – The Relation of the Perceived Environment to Fear, Physical Activity, and Health in Public Housing Developments: Evidence from Chicago

Free full articles on the built environment: Journal of Health Politics, Policy and Law — Table of Contents (June 2008, 33 [3])

Neighborhood safety, collective efficacy, and obes…[Obesity (Silver Spring). 2006] – PubMed Result