There’s new study that purports to tell us what we think we already know about weight stigma and physical activity: when you perceive more weight stigma in your life, you are less likely to engage in physical activity. The study, in BMJ Open, is here.
Here’s the abstract from the study:
Objective To examine the association between perceived weight discrimination and physical activity in a large population-based sample.
Design Data were from 2423 men and 3057 women aged ≥50 years participating in Wave 5 (2010/11) of the English Longitudinal Study of Ageing. Participants reported experiences of weight discrimination in everyday life and frequency of light, moderate and vigorous physical activities. We used logistic regression to test associations between perceived weight discrimination and physical activity, controlling for age, sex, socioeconomic status and body mass index (BMI).
Results Perceived weight discrimination was associated with almost 60% higher odds of being inactive (OR 1.59, 95% CI 1.05 to 2.40, p=.028) and 30% lower odds of engaging in moderate or vigorous activity at least once a week (OR 0.70, 95% CI 0.53 to 0.94, p=.017).
Conclusions Independent of BMI, individuals who perceive unfair treatment on the basis of their weight are less physically active than those who do not perceive discrimination. This has important implications for the health and well-being of individuals who experience weight-based discrimination, and may also contribute to a cycle of weight gain and further mistreatment.
Okay, this is probably no news to blog readers. First of all, we hear about fat shaming around physical activity all the time. One of the most recent episodes was the Twitter kerfuffle around Nike’s recent release of a larger-sized exercise clothing line (well, up to 3X). There were lots of tweets arguing (no, not arguing, rather declaiming) that manufacturing larger exercise clothing would… I can hardly bring myself to type this… encourage people to become fatter…. uh, because they now can?
As a philosophy professor who teaches introductory logic, I’m having trouble following the inferential thread here. Suffice to say, people weighed in against the Nike decision, engaging in all manner of fat-shaming, healthist trolling, and name-calling. I won’t even link to the discussion; rather, here’s my response to those folks:
But let’s get back to the study and my promised thoughts on it.
First of all, a science wonky comment: there’s a big big big difference between statistically significant differences among groups and clinically significant differences among groups. Let’s look at the results in bar graphs below:
Yeah, the print is tiny, but all you need to see here is that the differences in amount of physical activity (divided into inactive, light, moderate and vigorous) are pretty small. One might expect this in their sample, which was people aged 50 and above. Why?
First, it’s a big sample that seems pretty heterogeneous, which means the differences will be dampened by other potential factors the researchers aren’t controlling for. Second, digging into the demographics of the sample, the weight stigma group is predominantly lower-income (no surprise there). The weight stigma group is also on average heavier than the non-weight-stigma group (duh).
This suggests to me two confounding factors: 1) lower-income people generally have less access to physical activity because of less money and less time; 2) overall physical activity tends to decline with both age and increased weight (especially among women, who are 55% of the sample).
Here’s a study showing relationships between both workplace conditions (for workers in hospitals in Boston) and age with BMI. What it suggests is that as age increases, so does BMI, regardless of type of job; and, as control over one’s job conditions increases (and this happens with higher-income earners), physical activity increases.
One final nitpick (for now): relative to the sample in the weight stigma study (about 5500 people), the group reporting weight stigma was very small (268). The researchers thought this group was big enough to get a scientifically acceptable set of results, but this raises questions for me: 1) is there actually much more weight stigma in the group, but people aren’t either willing to report it or experiencing it in a more subtle way? 2) are the incidence or effects (two very different things) of weight stigma lower in people over 50? In short, this study raises some interesting (to me) questions about weight stigma and physical activity, but it doesn’t answer any.
Which brings me back to the title of this post: science is hard, and figuring out how to understand relationships between weight stigma and, well, anything else is also hard.
What’s not hard to figure out is this: fat shaming is rude and wrong and unhelpful for anyone. And my non-scientific solution for combating fat shaming is this:
Science is hard! One of my hypotheses, from a very non-scientific pov, is that identity affects activity and vice versa. So I consider myself an active person even at times when I have not been active for a week or whatever amount of time. Because my general pattern is to be somewhat active, I continue to carry that identity. And that identity makes me more likely to choose to be active in my leisure.
Whereas my family member, who is subject to more weight stigma, does not consider him/herself as active and then doesn’t choose to be active in leisure time. It’s a complicated issue, but I think the important but subtle effect of identity is ignored more than it should be.
From the psychological sciences side of thing we call this phenomena “self-efficacy” which is basically the idea that how you view yourself can change your goals and behaviors. Its been shown that people with a high self efficacy for a behavior are more likely to engage in that behavior.