Every so often you’ll see or hear a media story about the dangers of overweight employees and obese staff in the workplace, and how some have been fired over issues relating to their size. But really, how prevalent is either phenomenon?

No one should be made to feel self-conscious about their weight, and defining people by their appearance is a disagreeable bias to which we’re all prone. Yet there are several employment concerns surrounding workers who score high on the Body Mass Index (BMI), and though some are related to issues of discrimination, others have to do with health and safety.

On the discrimination side, The Conversation found that even a slight weight gain can make a person far less likely to succeed in a job interview or attain a promotion, especially if they are a woman. As far as health and safety are concerned, obese workers are more likely to take sick leave and be less productive, find it difficult to perform certain physical tasks, and can require workplace equipment and environment standards to be changed to accommodate their size.

All that being said, there’s a real difference between overweight and obese that sometimes gets lost. Most recently the Herald Sun published an article about Victorians who were “sacked or told to lose weight because their size makes them too dangerous to work”. It’s a good example of why clarity around this issue is so important.

The Herald Sun article begins by mentioning the Australian Institute of Health and Welfare (AIHW) finding that almost two in three Australian adults are overweight or obese. It then adds “lawyers say they are being inundated with “occupational obesity” cases involving workplace injuries, illnesses and risks to their business caused by overweight workers”.

The combination of these two facts makes it seem as though we’re surrounded by walking workplace hazards. But the vast majority of Australians, even those two out of three who are technically overweight, are not workplace risks, and statistically there’s little chance that any single one of them will be sacked. Lawyers being “inundated” is a subjective description of the commonality of the problem based on anecdotal evidence, not data.

Dig into the specific cases in the report and compare it to the general tone of the intro and you find an unhelpful blurring of the line between overweight and obese. From the perspective of the AIHW, overweight is someone with a BMI between 25 and 30. Obese is anyone with a BMI over 30.

The actual men and women who are being asked to lose weight or fired in these articles are not representative examples of Australians, they are on the very highest threshold of BMI – often scoring 40 and above (on the AIHW BMI calculator the scale ends at 40+). For instance, the Herald Sun report contains the story of a truck driver who was sacked after refusing to follow the health program set up by his employer. He was 190kg. Even assuming he was quite tall, say 190cm (6ft 2in), his BMI would be an exceptionally unhealthy 42.5.

Maintaining a clear idea of the gap between overweight and obese is especially important considering the relatively imprecise and arbitrary nature of BMI. The index doesn’t distinguish between varying kinds of weight – it cannot tell the difference between a gym junkie loaded with muscle and a couch potato filled with potato. It also doesn’t distinguish between different varieties of fat, some of which are much unhealthier than others: it’s possible for someone with a healthy BMI to have a hazardous level of “visceral fat” – a pot belly. Finally, the index doesn’t take fitness into account. An active person (someone tested as fit) with a BMI in the obese range is much healthier than an equivalently sized person with a sedentary lifestyle.

HR having to deal with issues regarding employee weight will become increasingly common so long as national obesity averages grow. But “increasingly common” should never be confused with common.

If you want to know more about the line where obesity becomes a workplace issue, read our article from earlier this year.