Fatness – being overweight/obese is in most cases a symptom, not a negative health outcome in itself. It is defined by the ratio of your height to your weight and doesn’t take into account body composition, i.e. whether this height and weight ratio comes from a body builder, someone with excess fat, a pregnant woman, or someone with excess fat who had a leg amputated and consequently has the “right” height to weight ratio. It’s too blunt of an instrument to take into account whether someone’s bone structure and musculature resembles a refrigerator or a giraffe. It doesn’t consider how much exercise someone is getting, whether their calories are coming from produce or deep-fried Mars bars, genetics, stress, exposure to environmental contaminants… essentially, it is just about the bluntest means of talking about health that the field of health has. We only hear about it so prevalently for two reasons: 1) it gets used frequently in studies because it is quick, easy, painless, and cheap to measure someone’s height and weight. Especially compared to drawing blood or performing a cardiovascular stress test. 2) it’s in the news all the time, not because it is terribly relevant, but because a three-letter abbreviation (BMI) is more accessible to the general population than medical terminology like “adipose tissue” and “lipid profile”, and articles about fat get clicked on. That’s why you see ads like
Because it works. People click on that stuff like crazy. And what’s on the cover of supermarket tabloids?
But cardiovascular disease isn’t caused soley by a few extra inches on your waist. It’s a subtle distinction between correlation and causation: for most of us, poor diet and exercise habits (A) cause fat cells to grow (B) and a long list of health problems (C). But this is a case of A causes B, and A causes C. B did not cause C, except in the case of mechanical issues (sleep apnea) and hormone-mediated diseases like diabetes and some cancers. People who won the genetic lottery and can eat junk food and watch tv all day without gaining weight are still increasing their risk of dying, and someone who is overweight but eats well and exercises might live to see 97. The greatest increase in health from exercise is reaped by people who are just transitioning from a sedentary lifestyle to an active lifestyle – before any weight loss is likely to have occurred .
Reminding girls that they are girls decreases their test scores (the official terminology from psychology is “stereotype threat”), and the appearance of girls and women is heavily policed and held to a mostly unobtainable standard , so it doesn’t seem to be a stretch that constantly talking about fatness could make people who aren’t thin feel like there isn’t a place for them in “bicycle culture” or other forms of active transportation. I wondered if I might be the only person to worry about this, but Google quickly turned up Ms. Kinzel’s experience:
“I’m using the elliptical trainer at the gym. A man walks by and gives me an encouraging pat on the shoulder. “GOOD FOR YOU!” he says loudly, pointedly, a little patronizingly.
His intentions may well be positive, but in reality he has drawn attention to the perceived discrepancy between my apparent interest in exercise and the size of my body. He has pointed out that seeing people who look like me exercising in public is a strange and unfamiliar occurance, an idea rooted in the assumption that fat people are uniformly lazy and unhealthy, and I, as an exception, therefore deserve to be recognized and lauded. I feel singled out and othered, and very uncomfortable.” 
Unfortunatly, exercising more isn’t a silver bullet for weight loss. Nothing is . Even people who don’t experience stereotype threat could experience run-of-the-mill discouragement at not making much progress towards the goal of being skinny, if we promote walking and biking for the purpose of weight loss. Most of the weight gain Americans have been experiencing for the past couple of decades can be attributed to eating more, not exercising less . People who walk and bike more might engage in less of other forms of exercise, such as sports or a gym membership. Or they might work up more of an appetite and eat more in compensation for increased activity. Real, permanent weight loss is very rare.
What we as Planners need to do is stop linking active transportation to weight loss. We run the risk of discouraging people from improving their health and the environment when the pounds don’t melt away, or they lose some weight but not enough to stop viewing themselves as “fat”. Whether or not weight loss happens, exercising more improve blood pressure, cholesterol, cancer risk, hormone balance, sleep quality, bone density, inflammation, immune response, and mental health. And the planet. We need to hear much more exhortation to quit looking at the scale and just go ride a bike, and it should be coming from the national level such as the CDC. This is an issue where medical credentials matter, and the local City Council is not the appropriate level of government. Michelle Obama's "Let's Move" campaign carefully avoids fat-shaming, but still puts a large emphasis on measuring the success of healthy eating and exercise by largeness. To improve utilization of active transportation for health improvement, and not unecessarily discourage people, takes a better understanding of psychology.
1. Running Doc: Biggest health benefits from exercise come when sedentary people start a program. (n.d.). NY Daily News. Retrieved June 10, 2013, from http://www.nydailynews.com/sports/more-sports/exercise-benefits-start-program-article-1.1336187
2. Dreifus, C. (2012, May 14). A Mathematical Challenge to Obesity. The New York Times. Retrieved fromhttp://www.nytimes.com/2012/05/15/science/a-mathematical-challenge-to-obesity.html
3. Parker-pope, T. (2011, December 28). The Fat Trap. The New York Times. Retrieved from http://www.nytimes.com/2012/01/01/magazine/tara-parker-pope-fat-trap.html
4. What’s Wrong With Fat-Shaming? (n.d.). Retrieved June 10, 2013, fromhttp://www.xojane.com/issues/whats-wrong-fat-shaming
5. Matthew S. McGlone, Joshua Aronson, Stereotype threat, identity salience, and spatial reasoning, Journal of Applied Developmental Psychology, Volume 27, Issue 5, September–October 2006, Pages 486-493, ISSN 0193-3973, 10.1016/j.appdev.2006.06.003.
6. Pretty much all media.