I thought I would go ahead and post about the article I referenced during Dr. Saviano’s visit to our class last week. He asked what some of the causes of obesity are, and I answered that marriage was a major culprit in contributing to the evolutionary development of obesity as a phenotype in the US and other countries.
In an article by David Allison and colleagues, they examined the health records of individuals’ BMIs at age 13 using the national health registry in the Netherlands, and compared this data via personal identification numbers to marriage and health registries during traditional marrying decades later in life. Using various statistical analyses that I won’t go into here, the study showed that for individuals who were in the 90th to 95th percentiles for BMI at age 13, their BMIs increased steadily during decades when people traditionally get married. In other words, folks with a high BMI at age 13 continue to get fatter over time, as is reflected in most of the obesity literature.
When it came to marriage, folks in the 90th and 95th percentiles for BMI at age 13 were highly likely to marry someone who also had a correspondingly high BMI at age 13. This is regardless of weight loss or change in body type in the interim years between age 13 and marrying age. In short, the study showed that if a person was overweight as a 13-year-old, that person would have a high chance of marrying someone who was also overweight as a 13-year old, regardless of either partner’s weight on their wedding day.
The authors argue that because BMI at age 13 suggests a genetic predisposition to overweight as an adult, and because assortative marriage (marrying based on similar phenotype or genotype) appears to occur within these populations (and the general population as well), assortative marriage could be a prominent factor contributing to the obesity epidemic. They say, “Genetic predisposition toward a high BMI in both spouses—apparent already in childhood—may predispose their offspring towards the same trait to a higher degree than by simply adding the effects. The offspring may inherit several interacting risk alleles from both parents, and, in addition, homozygosity at loci associated with obesity may allow recessive loci to be expressed” (p. 5). Essentially, two people who are predisposed to obesity because of their genetic profiles will create children who are also predisposed to obesity.
I’m fascinated by this research because of its implications for communication activities aimed to change health behaviors. While the media and the public often attribute obesity to personal choice and individual behaviors, this research suggests other, less easily mitigated factors to consider. While we can’t tell people who to have children with, this research may demand new and different behavior change research to effect health outcomes.
Ajslev, T. A., Ängquist, L., Silventoinen, K., Gamborg, M., Allison, D. B., Baker, J. L., & Sørensen, T. I. A. (2012). Assortative marriages by body mass index have increased simultaneously with the obesity epidemic. Frontiers in Genetics, 3. doi:10.3389/fgene.2012.00125
Wow, Jill! This certainly is fascinating research! Previously, I heard from my professors about the possible role genetics has to play on various factors. One potential hypothesis is that obese people do not release enough ghrelin, the hormone responsible for satiety. There are also things like Prader-Willi syndrome, which is a disease where people are always hungry, which adds to childhood obesity. While these are all likely contributors to obesity, I will offer an opposing argument. What role do you think behaviors have in confounding in this marriage study? Often, people encourage each other’s health behaviors. If you are surrounded by people who work out all the time, you might be more motivated to work out yourself. These behaviors are exemplified with products such as Fitbit, which can post your health behaviors to social media. This allows friends to encourage each other to do more. If you marry someone who has poor health behaviors, you likely will not be as motivated to eat healthy food. On the other hand, if you marry someone who has good health behaviors, you may be more inclined to participate with them.
ReplyDeleteMarcel! I love this comment! I am in possession of a book called "XL Love" right now that is all about how the obesity crisis has changed romantic relationships. I will not be able to read it until December 13th, but I listened to an interview with the author and it was all fascinating. Like for example, in heterosexual relationships, if the woman is heavier (proportionally, not in terms of pounds) than her husband, they are more likely to have marital problems than if the woman loses weight and weighs less proportionally than the man. Or that it's fine if one partner loses weight and the other doesn't if the marriage was strong to begin with. But if the marriage had other problems to begin with, weight loss is almost guaranteed to lead to divorce. Merry Christmas to me when I finally get to read this book!
ReplyDeleteI think that all of the patterns you mention above could be contributing to the crisis IN ADDITION to the Allison article. I have no trouble believing also, based on "XL Love," that ANY relationship dynamic based on weight, food, or size, could have acute implications for love, relationships, and parenting. In my own relationship, for example, my partner cut out almost all animal products after he met me. It wasn't because I convinced him to; it's just that he liked what I cooked and didn't have a problem eating it. He then realized that he felt better, was a better and more competitive athlete, had better skin, etc. (I actually think, in response to your post on the FDA labeling, that improved skin would be a key way to get people to eat more healthy. Acne sucks.) On the other hand, I definitely eat more processed food being with him because he keeps it in the house for the kids, because they were raised that way and even thought they love kale salad and asparagus since I've come into the picture and it's been on their plate the requisite 13 times, still "require it." I don't see any drastic changes in my health, but if I did it would be really hard to stop eating, for example, tortilla chips, because they're just always around. So he benefits and I don't, in a way.
This is pretty cool research! I've always been curious about the potential impacts parents can have on their children's BMI, whether that be an aquired predisposition or shaping behaviors. Do you know of any research being done into environmental factors with influence on obesity? Not the impacts of factors like air/water quality and exposure to toxics, but the impacts of the built environment around people. What kinds of built environments encourage healthier eating and lifestyle choices?
ReplyDeleteColorado has a low obesity rate every year, which is kind of easy to rationalize: there are more options for year-round outdoor activity. Not everyone has the means to travel to the mountains on the weekends, though. I'm sure there is more to the story though, Colorado is a state with a large city and a significant agricultural presence, and cities known for harboring professional athletes (Boulder, CO and Colorado Springs where the US Olympic training center is). Is there something about how towns/cities are built that affects the way people work, travel, purchase food, and spend leisure time in one state or municipality that promotes lower BMI than in another? Health values and behavior can shape how people interact with their environments, but environments can also impact values and behaviors (or so I would think).
Matt, I just posted on the built environment!
ReplyDelete