Morbid obese a rapidly growing population in the U.S.

In a study to be published later this year researchers have found that not only are Americans getting fatter each year but the number of severely overweight members of the population is increasing twice as fast as other obese Americans.

The severely obese, those who are 100 pounds or more overweight, increased by 50 percent from 2000 to 2005 in the U.S. which is twice as fast as the growth seen in moderate obesity.

According to a RAND Corporation study the number of people at the upper end of the weight scale continues to rise regardless of the public attention devoted to highlighting the risks of obesity and the increased use of radical weight reduction methods such as bariatric surgery.

Bariatric procedures limits the amount of food patients can eat and such surgeries increased from an estimated 13,000 in 1998 to more than 100,000 in 2003 and it is estimated that as many as 200,000 of the procedures were performed in 2006.

RAND is a nonprofit research organization of which RAND Health is a division and is one of the nation's largest independent health policy research programs.

The author of the report Roland Sturm who is an economist, says that from 2000 to 2005, the proportion of Americans with a Body Mass Index (BMI) of 30 or more increased by 24 percent, while the proportion of people with a BMI of 40 or more increased by 50 percent; the proportion of Americans with a BMI of 50 or more increased by 75 percent.

The heaviest groups says Strum, have been increasing at the fastest rates for the past 20 years.

In order to be classified as severely obese, a person will have a BMI (a ratio of weight to height) of 40 or higher which is approximately 100 pounds or more overweight for an average adult man.

The typical severely obese man weighs 300 pounds at a height of 5 feet 10 inches tall, while the typical severely obese woman weighs 250 pounds at a height of 5 feet 4 inches.

People with a BMI of 25 to 29 are considered overweight, while a BMI of 30 or more classifies a person as being obese.

The study found that on the basis of self-reported height and weight, which tends to understate actual BMI, 3 percent of Americans are already severely obese.

Since that is the fastest growing group of obese Americans, this has wide implications for health providers in the future as this group place much higher demands on such services.

Research suggests that middle-aged adults with a BMI over 40 can expect to have double the health costs of those experienced by normal weight peers, while moderate obesity (a BMI of 30-35) is associated with a 25 percent increase.

Sturm says despite the rise in bariatric surgery no noticeable dent can be seen in the trend of morbid obesity; he says the findings challenge a common belief held by physicians that people who are obese are a fixed proportion of the population and are not affected by changes in eating and physical activity patterns in the general population.

The study suggests that being clinically severe obese is no longer a rare pathological condition among genetically vulnerable individuals, but is now an integral part of the population's weight distribution.

As the whole population becomes heavier, so the extreme category, the severely obese, increases the fastest.

Sturm says even though it is common knowledge that exercising more and eating less helps control weight it is not easy for some to do so in the current environment where urban developments are "car-friendly and bike/pedestrian-hostile", and sedentary jobs, television viewing, and low-cost junk foods are readily available.

Sturm says these are major factors in the U.S. obesity epidemic, and environmental interventions are needed to counter the obesity epidemic, similar to tobacco and alcohol policy, which are unlikely to be enacted in the near future.

The study will appear later this year in the journal Public Health.