Picture yourself with no body fat. That's what Harvard Medical School researchers recommend for your health in the July 9 issue of the Archives of Internal Medicine

The researchers' new study reports that even a few extra pounds of bodyweight raises the risk of chronic diseases like diabetes, gallstones, hypertension, heart disease, and stroke. But don't start crash dieting yet.

The researchers' fat heads and research budgets are in desperate need of liposuction.

The researchers concluded "adults should try to maintain a body mass index between 18.5 and 21.9 to minimize their risk of disease." Body mass index (BMI) is a ratio of weight in relation to height. Current U.S. dietary guidelines classify BMI as follows: Less than 18.5 is underweight, 18.5 to 24.9 is the healthy weight range, 25.0 to 29.9 is moderately overweight, and 30.0 or more is severely overweight or obese.

Consider what the researchers' recommendation calls for in terms of pounds and inches. Adults who are:

Five feet tall should weigh between 97-112 pounds;
Five feet six inches tall should weigh 118-136 pounds;
Six feet tall should weigh between 140-162 pounds; 
- Six feet four inches tall should weigh between 156-180 pounds.

Don't measure up? Neither do most Americans. By this standard, the average U.S. man (5 feet 9 inches tall) is 31 pounds overweight and the average woman (5 feet 4 inches tall) is 24 pounds overweight, based on data from the U.S. Centers for Disease Control and Prevention.

The great irony here is that Americans have never been healthier, as measured by life expectancy, the traditional and most objective indicator of population health.

Between 1960 - the year the bodyweight nannies use as a benchmark for measuring trends in bodyweight - and 1997, U.S. life expectancy increased about 10 percent from 69.7 to 76.5 years. Not bad for a nation of supposed "fatsos."

So what's the basis for calling for our body ideals to be Jack Sprat and Olive Oyl? Weak statistics calculated from poor quality and incomplete data.

For a specific population of nurses and other health professionals, the researchers developed statistical associations between bodyweight groups and the rates of diabetes, gallstones, hypertension, high cholesterol, colon cancer, heart disease, and stroke.

But all the statistical associations for the "few pounds overweight" group (BMIs between 22.0 and 24.9) are too weak to be considered reliable. In any event, these associations are only statistical, not scientific, in nature. That is, cause-and-effect between being a "few pounds overweight" and the occurrence of disease was not scientifically proven.

This is not surprising since the only disease risk factors other than BMI considered by the researchers were age, smoking status and race. Health history, family history, physical activity, socioeconomic status, to name a few, were not considered by the researchers.

What's the researchers motivation to scare us about not having the perfect figure?

Public health professionals have been largely successful in eliminating the traditional and most significant threats to public health in the U.S., chiefly infectious disease.

In search of a ongoing reason to be, many in the public health establishment have taken to "medicalizing" unpopular or politically incorrect behavior, including overeating, eating the "wrong" foods, smoking, alcohol consumption, not exercising, and even gun ownership.

Three years ago, for example, the federal government changed the definition of "overweight" so that 37 million more Americans became "overweight" literally overnight. This "epidemic" of obesity is now being used to justify more government research grants and bureaucracy. Talk about an expanding waistline.

Aside from taxpayer dollars being wasted on useless research, unwarranted alarm about our bodyweight may have unintended consequences.

Former Surgeon General and weight-loss advocate C. Everett Koop criticized the 1998 federal BMI guidelines saying: "I worry that people will say: 'This goes too far. I quit.' It is like someone in a race saying, 'They moved the finish line.'"

The public health nannies should stay out of our waistlines and find something more useful to do. Every dollar spent on bogus alarmism is a dollar diverted from more productive research into treatments and cures for diseases.

A fat-free America? We'd be better off with a junk science-free America.

Steven Milloy is the publisher of JunkScience.com, an adjunct scholar at the Cato Institute and the author of the upcoming book Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).