For the past five years, I’ve pulled a nasty trick on students taking my college Exercise Prescription course. I’d explain that the assessment for the course included a couple assignments and practicals and a final examination accounted for the other 50% of their final grade. Over the past few years, I’d noted some complacency and those with high internal assessment seemed to coast into the final exam knowing that they didn’t need a great exam result to get their 50% passing grade. Scraping through with a 50% pass wasn’t really doing my course justice and I wasn’t confident that they had really mastered my ject area. So, I’d announce – this year they would need to get at least 65% overall in the course to obtain a pass – and I hope they understood my reasoning. I could see that I now had most student’s attention and that they were looking a little uncomfortable and concerned – but of course, being the first class, no one really knew me well enough to ask, challenge or complain.
Quickly switching topics, I’d then tell them about my recent sabbatical experience walking through the University of Denver campus. One day I noticed a booth in the student centre offering monetary incentives for losing weight. Always up for a challenge (and free money), I slipped into the booth, entered a few details on the screen and stood on a scale which weighed me and somehow gauged my height. The bad news – my body mass index (BMI) was calculated to be 27.8 kg/m 2 which placed me in the overweight category and told me I needed to lose weight for the sake of my health. Whoah – what? Hang on a minute there! Look at me, I’d ask the class. I know I’m not a thin, lean machine – but I couldn’t possibly be overweight – could I?
When I got home that night I recalculated my BMI – same number – about 27.8 kg/m2 . I checked my rating with the New Zealand Heart Foundation web site – same result and similar advice – I was assessed as being at risk of suffering from obesity-related health problems. This was starting to stress me out, and I was pretty sure I’d checked my BMI before and it had never been a problem.
So I did some further research and found that back in 1998 a panel from the National Heart Lung and Blood Institute (Report here) had decided that an ‘overweight’ threshold of 27.3 kg/m2 for women and 27.8 kg/m2 for men was too liberal for their liking. So they made a slight adjustment and slid that scale to the left so that the threshold for overweight was now 25 kg/m2 . Their decision was based on epidemiological data that showed increases in mortality with BMIs above 25 – `but they did note that increases in mortality were modest until a BMI of 30 was reached. We will certainly trouble that link between weight and health in future blogs. A 10th man would look at the BMI thresholds of 25, 30, 35 and 40 and think – Hmm that seems a little bit too even and convenient. But here’s the kicker – shifting that threshold meant that roughly 29 million citizens (Washington Post Article here) of the USA went to bed on June
3rd 1998 at a normal healthy weight feeling pretty good about themselves, and woke up the next morning overweight, at risk of obesity-related disorders and probably feeling pretty lousy about being stigmatised. Of course many of those people are in great shape, healthy and have no more risk than the next person, and of course now they’ve also been labeled!
So I’d ask the students – does it seem fair that a group would make the decision to shift the bar (and likely help pad their overweight hysteria statistics – that’s another story we will get to) and negatively affect so many peoples’ lives? By now some of them were realising that the grades and BMI stories were related and I’d explain that there was no defensible logic to me arbitrarily raising the passing grade for my course and it was a hoax.
I realise that this was pretty corny but they understood the context and it helped set the scene for the course where we would critique some of the thinking around testing and measurement because we do this sort of thing to people all of the time.