In 1998, the NIH and CDC lowered the BMI cutoff for “overweight” by 2.8 points for men, and 2.3 points for women. This had the effect of suddenly making millions of Americans overweight. Ragen often points to this event as a diet industry conspiracy perpetuated by a group of corrupt doctors. As usual, Ragen is misrepresenting the facts.
The reasoning for altering the definition of overweight is explained in great detail in the 230-page 1998 NIH report, Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. To interpret the change, it is important to understand the previous BMI cutoffs had nothing to do with mortality risks, and were actually completely arbitrary values chosen for the sole purpose of statistical comparison between NHANES releases.
Nationally representative U.S. health examination surveys, in which weight and height were measured in samples of the population, date back to 1960. Beginning with the Second National Health and Nutrition Examination Survey (NHANES II) (1976-1980), the definition of overweight that has been used to compare these epidemiologic surveys has been a statistical one that corresponded to the 85th percentile of body mass index (BMI) for men and women aged 20 through 29 years in NHANES II with no particular relation to a specific increase in disease risk.
Clinical Guidelines, page 6
For men, this was a BMI of 27.8, and for women, 27.3. Because the previous cutoffs were completely meaningless in clinical practice, the committee sought to define a BMI cutoff actually based on epidemiological data. After extensive review of the literature (almost 800 scientific references in total), a cutoff of 25 was chosen as the approximate point where mortality tends to increase. This brought the NIH and CDC guidelines up to date with the World Health Organization’s existing guidelines.
The NIH report is careful to note that BMI cutoffs for overweight and obesity are somewhat arbitrary, and that the increase in mortality is modest until a BMI of about 30 is reached. It also advises clinicians to use sex-specific waist circumference cutoff for patients with BMIs of 25 to 34.9 to identify increased disease risk. There is no suggestion to rely solely on BMI unless a patient is extremely obese.
Ragen doesn’t tell her readers any of this. In fact, she puts more spin on it by making it a great big conspiracy against fat people.
Three members of the committee responsible for making the recommendation had direct ties to pharmaceuticals that manufactured diet pills for profit. A fourth member was the lead scientist for the program advisory committee of Weight Watchers International.
What Ragen doesn’t say in this scare quote is that the committee had 36 members, all PhDs and/or MDs and experts in their fields. Ragen wants her readers to believe 4 committee members with supposed links to the diet industry were able to first influence the WHO to change the BMI cutoff for overweight, then convince 32 other committee members and both the NIH and CDC to discard all the evidence and also change the cutoff, all as some kind of conspiracy to get “potential clients”. It sounds completely absurd in its proper context, but this is the kind of evidence Ragen relies on as a “trained researcher”.
The other thing Ragen and other fat acceptance advocates frequently do is completely misrepresenting what actually happened in 1998, as well as how data before and after the change is compared.
Talking about a change in “obesity” levels since 1980 without discussing the fact that the measurement was changed in 1998, altering millions of people’s BMI classification overnight (on recommendations from a committee that included representatives from pharmaceutical companies that manufacture diet drugs and the chief scientist of weight watchers) does not have the ring of sound science.
This particularly egregious bit of misinformation comes from today’s Dances with Fat post. Ragen is implying the definition of obesity was changed in 1998, which is entirely false. The 1998 NIH report did not redefine the BMI cutoff for obesity, and had no effect on obesity levels, which were already rising dramatically and continued to rise.
Ragen also likes to imply that in retrospective studies, old data uses the old BMI cutoffs, while new data uses the new cutoff, which would mean data before 1998 is not comparable to data after 1998. Essentially, the obesity crisis is somehow manufactured by data manipulation. This is total nonsense of course. In fact, when comparing historical data with new data with both using the BMI 25 cutoff, it is immediately obvious prevalence of overweight under the new definition was stable from at least 1960, even if it meant more Americans were technically considered overweight. The real issue was the enormous jump in obesity prevalence, which has now reached almost 36% in present day.
The average prevalence of overweight using the BMI 25 cutoff has actually dropped significantly in recent years as more people become obese. This is an obesity crisis, not an overweight crisis, and bumping down the BMI cutoff for overweight slightly made no difference whatsoever.
Ragen likes to childishly write out the equation for BMI for her followers as “weight in pounds times 703 divided by height in inches squared” to imply a completely arbitrary relationship between height and weight. This is quite telling about how much she respects their intelligence, and as usual her “science” is worth about as much as her non-existent college degree.