[ASC-media] More on obesity: First message

Chris Forbes-Ewan forbes-ewan at tassie.net.au
Wed Mar 19 22:06:28 EST 2003

A couple of weeks ago I promised to send more information about obesity. Because the subject is so complex, I will send a series of messages rather than try to cram all that I want to say into one overwhelmingly long discussion. 

In this message I will (very briefly) describe the obesity epidemic. Future messages will address, inter alia, health problems associated with obesity, possible causes, suggested treatments, and actions taken by health authorities to try to reduce the problem. 

Unfortunately, in attempting to make it suitably brief, the discussion in each message is likely to be a gross oversimplification of an extremely complex subject--and one that is not well understood. In fact, at the moment I feel a little like the art critic who knew a lot about art, but didn't know what he liked ... I also know (or think I do) a lot about obesity ... I'm just not sure how much of what I *know* is actually so!


As is probably fairly well known by now, affluent populations generally (and not just in the Western world, but also those affluent groups who live in developing nations) are undergoing an epidemic of obesity. (See below my signature block for the definition of 'obese' and other related terms).

And the obesity epidemic appears to be out of control. About six years ago, one leading US researcher estimated that by about 2150 every American who was not genetically protected from obesity--by having an inherited propensity to remain slim no matter how obesogenic the environment--would be obese. Based on the rate of increase in levels of overweight and obesity over the previous five years, in 2002 he revised his estimate to about 2050. That is, the estimated time it will probably take for obesity to spread as far as it can has reduced by a century in just five years! Consistent with this, another expert estimates that the proportion of the US population that is obese will increase by one-third from 2003 to 2008.

While the US has the reputation of being the most obese nation on earth, in the 'obesity stakes' the Americans are leading by only a short half-head (if at all), with Australia poised to take the lead if our northern hemisphere cousins falter. Illustrating this, an Australian survey conducted in 1983 found that 35% of women and 43% of men were above the healthy weight range (HWR), with 9% of adults being actually obese. But by the year 2000 approximately 68% of men and 50% of women in Australia were above the HWR, with 20% being obese (more than double the obesity level of just 17 years previously, and very close to the percentage of American adults who are obese). 


Chris Forbes-Ewan
15 Hedley St
Scottsdale Tas 7260

Phone: Int + 61 3 6352 2092 (03 6352 2092 within Australia)

Everyone should be a winner in the human race


The 'body mass index' (BMI) is used by both World Health Organization and the National Health and Medical Research Council in Australia. BMI is calculated as:

BMI equals weight (kg) divided by height-squared (where height is in metres).

A BMI < 18.5 is defined as 'underweight'

The 'healthy weight range' (HWR) is BMI in the range 18.5-24.9 

'Overweight' is BMI 25.0-29.9

'Obese' is BMI 30.0 and above

For example, a very large man, who weighs 100 kg and is 2.00 m tall, has a BMI of 100/(2^2) = 100/4 = 25.0 (borderline between HWR and overweight).

NOTE: These definitions do not necessarily apply to individuals--some very muscular people may be 'overweight', yet their extra weight is due to unusually well-developed muscularity, not to excessive body fat. For such people, other physical characteristics, such as waist circumference or waist-to-hip ratio, may also be needed to determine if the overweight is most likely attributable to excessive body fat or to muscle.
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