US obesity grows 74% in a decade



Robert Walgate




A nationwide, randomized telephone survey by the US Centers for Disease Control and Prevention has shown a fat 5.6% growth in obesity in the United States in the single year 2001–02, and a massive 74% since 1991. Type two diabetes is following the same track (Journal of the American Medical Association, Vol. 289, 1 January 2003, p. 76-9).

The largest telephone poll on health ever conducted in the US reached nearly 200 000 individuals over 18 years old, outside institutions or the armed forces (where diet is effectively controlled). The "Behavioural Risk Factor Surveillance System" questioned people on their health and behaviour, including height and weight, and calculated their body mass index (BMI), which is weight in kilograms divided by height in metres squared. Overweight is classed as a BMI of 25 to 29.9; "class two" obesity as 30 to 39.9, and "class three" obesity as 40 or over.

The prevalences represent over 20 million obese men and 30 million obese women. Extreme, class three obesity affects 1.7% of American men and 2.8% of American women, the study showed.

Some 21% — over one in five — American adults are obese, falling either into class two or three; 31% of blacks are obese, according to the study.

The prevalence of diabetes, which correlates with obesity, has risen 61% in the US since 1990, and 8% over 2000–01 alone, to nearly 8% of the population, and 11% among blacks. Among all colours, diabetes was present among 13% — one in eight — of those without high school education.

However "these rates are no doubt substantial underestimates" the authors write. Smaller validation studies where weights and heights were actually measured showed people tend to overestimate their height, and underestimate their weight, the researchers say. The overall proportion of Americans who are obese could be as high as 30%, not 21%, they say.

Previous studies by the same team showed that under 20% of American adults who were trying to lose weight were following recommendations to eat fewer calories and increase physical activity to at least 150 minutes a week.

World Health Organization Genebra - Genebra - Switzerland