For too long “I’m watching my weight” has been used as a synonym for healthy living. But because in and of itself weight is no measure of health, we should focus our attention elsewhere.

There are medical contexts in which it is important to know or track a person’s weight (determining certain medication dosages, for example). There are sporting contexts in which participants are divided by weight class (e.g., wrestling). There can be identificatory value in listing a person’s general weight (on driver’s licenses and such). And of course it is essential to know how much weight a structure or vehicle can safely support, transport, etc.

That pretty much exhausts value of the data point that is human weight. Because it doesn’t tell you anything about your fitness level or the quality of your diet, while it may make sense to keep your kitchen scale, your bathroom scale should go out with the trash.

As Dr. Ellen Albertson notes, in the first few decades after the invention of the platform scale in the 19th century, weighing people was a sideshow entertainment, common at county fair where carnies would try to “guess your weight.” But in the American capitalist tradition, entrepreneurs seeing a chance to make a buck fabricated a correspondence between weight and health, and in the 1930s first bathroom scales made their way to market. One of the most successful makers of such scales called them “health-o-meters,” a name the company goes by to this day. By mid-century insurance companies and doctors offices were regularly referring to “ideal weight” tables when judging individuals’ health.

But the truth is that there is not—and never was—evidence suggesting a correspondence between weight and health. One of the first most obvious indicators of the fallacy in such a linkage is the fact that muscle is denser than fat. Let’s say Ken has always been a couch potato and subsists on a diet of fast food. But his New Year’s resolution is to get healthy. On January 1 he weighs himself: 200 pounds. He cuts down on the fast foot and drags himself to the gym a couple of times a week. After a month of hard work (it’s not easy changing a lifetime of bad habits) he thinks he feels and looks a bit better. But then he steps on the scale: 203! “What’s the use?”

Or take Kendra. She is moderately active with decent eating habits, but at 150 pounds her New Year’s resolution is to get thinner. She doesn’t really have time to work out more, so her plan is to eat less. She radically restricts her calorie intake, which makes her feel weak enough so that she doesn’t have the energy to hit the gym as often. When February 1 rolls around she does indeed look thinner, even if she’s also looking a bit pale. But when she jumps on the scale and sees “135,” she feels she must be on the right track.

Ken feels better and has gained muscle mass, indications of his improved health, while Kendra feels worse and has lost muscle mass, indications of diminished health. Yet each arrives at the wrong conclusion about the soundness of his/her regimen. Why do they let weight tip the scales in the wrong direction? Counterintuitive as it may be, in a culture where “overweight” is generally used as a synonym for “unhealthy” and doctors measure body weight during regular checkups as frequently as they measure an essential vital sign like blood pressure, it’s understandable why that number continues to make such an impact.

This obsession with weight is so insidious that it infected the next-generation shortcut connecting weight, fat, and health: body mass indexing, or BMI. As discussed in the International Journal of Epidemiology, although BMI itself was championed in 1972 by physiologist Ancel Keys in response to “the inadequacy of relative weight as a measure of fatness, pointing out the misinterpretations in muscular people and those with metabolic abnormalities,” even as BMI became the medical establishment’s go-to calculation for tell us whether we’re too fat, it was easy to demonstrate how flawed it was. In 1998, for example, an enterprising reader of the Chicago Tribune calculated the BMIs of the Chicago Bulls, a team in the midst of winning three straight NBA championships. According to BMI standards, only two of the 12 players on the Bulls roster were “healthy,” with Dennis Rodman, Scottie Pippen, and Michael Jordan—the Bulls’ three best players, renowned for their fitness level and extremely lean by any reasonable standard—qualified as “overweight.”

By the same token, an individual with a healthy BMI rating may in fact be carrying too much fat for his/her body. As a recent CNN article documents, “BMI misses about 50% of the people who still have dangerous amounts of fat. Those are typically people who have the proverbial beer belly, but are otherwise in decent shape. [… S]tudies have shown that excess belly fat, even if you are skinny elsewhere, may be even more deadly than being obese or overweight.”

According to a study cited by CNN (published in Frontiers of Public Health), 90% of adult men, 80% of adult women, and 50% of children in the U.S., New Zealand, Greece, and Iceland are “overfat,” a term referring to “the presence of excess body fat that can impair health, even for normal weight non-obese individuals.” Among the world’s 30 most developed nations, only Japan and Brunei do not have more than 50% of the population qualifying as overfat.

From joints problems to high blood pressure to increased risk of diabetes, heart disease, and certain cancers, the dangers of carrying too much fat are well documented. The problem comes from giving weight to weight as an indicator. Some bodies are just bigger or denser than others, and what is a healthy weight on one body may be too much or too little on another.

So you really may want to slim down, which is best achieved by the old standbys of exercising and eating right. Just don’t worry about watching your weight. That number on the scale doesn’t tell you anything you need to know.

About the Author:

Except for a four-month sojourn in Comoros (a small island nation near the northwest of Madagascar), Greggory Moore has lived his entire life in Southern California. Currently he resides in Long Beach, CA, where he engages in a variety of activities, including playing in the band MOVE, performing as a member of RIOTstage, and, of course, writing.

His work has appeared in the Los Angeles Times, OC Weekly, Daily Kos, the Long Beach Post, Random Lengths News, The District Weekly, GreaterLongBeach.com, and a variety of academic and literary journals. HIs first novel, The Use of Regret, was published in 2011, and he is currently at work on his follow-up. For more information: greggorymoore.com