Obesity Rates Over Time

Obesity has reached epidemic proportions in the United States. These increased body fat reserves are associated with an increased risk of numerous health problems, including coronary heart disease and heart attacks, diabetes mellitus, stroke, some cancers, and more. Obesity has become so prevalent in the U.S. today that it is difficult to remember that just a couple decades ago, the average American was not overweight, and few were obese. Below is a link to an animated graphic showing the remarkable increase in obesity in U.S. states over time. In the ideal case, the entire map would be colored the aqua color, since there would be data from every state but no obese people.

This is the first frame. See animated version.

As is commonly done, obesity is defined here based on the body-mass index (BMI). The BMI is calculated by dividing one’s weight by one’s height squared. It is traditionally given in SI units (that is, kg/m²), so if U.S. customary units are used, they must be converted. BMIs in the range from 18.5–25 kg/m² is considered normal or healthy. 25–30 kg/m² is overweight, and greater than or equal to 30 kg/m² is obese. (40 kg/m² or greater is often considered morbidly obese, or sometimes 35 kg/m² or greater along with other risk factors is included.) The use of BMI is imperfect (for instance, a very muscular person will have a high weight and therefore BMI), but in practice it is usually simple to differentiate obese from muscular people.

For instance, consider a 1.78-m (5 ft., 10 in.) tall person. The healthy range would be from 58.5–79.0 kg (129–174 lb.). Those weighing more than this would be overweight, and over 94.8 kg (209 lb.) would be obese. For a 1.63-m (5 ft., 4 in.) tall person, the healthy range would be from 47.4–64.0 kg (104–141 lb.). Greater than 76.8 kg (169 lb.) would be obese.

It’s easy to calculate your own BMI. There are plenty of BMI calculators and BMI charts on the Internet. But the fastest way is probably to use Google Calculator: just type your calculation directly into the main search box (see example).

The obesity data are taken from the CDC. I reformulated them into an animated GIF since I didn’t care for the original color scheme and also because that presentation isn’t easily exported to other sites. You are free to use the image (direct linking is fine), though I would appreciate a link back here if you do.

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Interactive Timeline of the Universe: The Big Bang, Formation of Earth, and Evolution of Life

Some time ago I came across a very nicely done Flash animation showing how the universe and Earth have developed to this point:

evolution — what next?.

The site features a timeline with a slider you can drag. It starts at the big bang, an estimated 13.7 billion years ago. Once the solar system forms some five billion years ago, it focuses on Earth. Since the most interesting things, from a human perspective, have happened recently, there are a series of supplemental sliders to focus on the most recent portion of each timeline. With simple animations, it’s a nice, easy way to visualize the history of our planet, and see just where our little story fits in.

Minnesota Is Now Smoke-Free

Today, 1 October 2007, a state-wide smoking ban took effect in my state. A major success for public health and especially employees’ health, this law puts major restrictions on indoor smoking in public places with relatively few loopholes. Bars, restaurants, and almost all other indoor locations are included. Private residences, hotel and motel rooms, cigar shops, and casinos and other establishments on Native American lands are exempt. As is well-known, there is an enormous body of scientific data indicating the harm smoking causes to bystanders. Those who work in establishments where smoking is permitted are especially at risk. As attention to public health mounts, smoking bans cover more and more of the United States—at the city, county, and state levels. According to Wikipedia, over half of Americans are covered by some sort of smoking ban.

Wikipedia also featured this interesting map of the United States, showing active and scheduled smoking bans. It uses an innovative “additive color key” to designate the type of ban.

State-wide smoking bans. Credit: Mike Schiraldi.

The gray states have no state-wide smoking bans. The red states, Idaho and Georgia, ban smoking in restaurants; the green ones (North and South Dakota) ban smoking in non-hospitality workplaces (that is, not restaurants or bars); and the yellow states (Nevada, Arkansas, Louisiana, Tennessee, and Florida) ban smoking in both. The lavender state (New Hampshire) bans smoking in bars and restaurants. The white states ban smoking in all three: bars, restaurants, and non-hospitality workplaces.

Birds’ Magnetic Sense May Be Visual

Many animals have senses that humans lack. One that is poorly understood is that magnetic sense (magnetoception or magnetoreception) that birds and other animals have. A LiveScience article today details some new research suggesting that birds may actually “see” magnetic fields. They found that visual regions of the brain were active during magnetic navigation and that some possibly magnetically sensitive molecules were located in the retinas, the light-sensing membrane at the back of the eye. While this isn’t proof, it is certainly suggestive. It could be that these birds see some sort of magnetic imagery overlaid on their normal vision. Or perhaps they perceive the magnetic fields in a totally different way.

Birds can travel the world without any of the gizmos that humans depend on, and a new study suggests how: Our feathered friends might “see” Earth’s magnetic field.

While other mechanisms are thought to help birds navigate, including magnetically sensitive cells within their beaks, their brain regions responsible for vision are in full gear during magnetic navigation, researchers said.

See the LiveScience article for the rest.

Energy and Health: Spotlight on the Lancet‘s Series Covering Climate Change and More

As a human and a resident of planet Earth, I care about my home and the environment, and for the other life that shares it with me. But as a physician, I have a special interest in examining the relationship between the health of our planet and that of human health; I have a strong desire to promote public health. And therefore I am indebted to Inel for bringing my attention (via a comment and a subsequent blog entry) to a wonderfully important series of articles in the Lancet covering the many-faceted relationship between energy and health. At the least, I feel that all physicians are obligated to read this series.

The Lancet is one of the world’s premiere medical journals (along with the New England Journal of Medicine, the Journal of the American Medical Association, and the British Medical Journal). In publishing this series, they are taking on a large, complex issue with significant public health implications that previously have not drawn much attention. Strategies to help ameliorate the problem are well–thought out. The series covers so much detail I’d like to devote a series of my own posts to discuss and analyze them.

Editor-in-chief Richard Horton writes the introductory comment, entitled “Righting the Balance: Energy for Health”:

The current debate about the impact of human beings on our planet—especially with respect to climate change—is one of the most important issues of our time. But that debate is presently unbalanced and too narrow. It neglects a far larger set of issues focused on energy—and health.

Energy is a critical, yet hugely neglected, determinant of human health. Health is an important enough aspect of energy policy to deserve a much greater influence on decisions about our future personal, national, and global energy strategies. Society suffers from a disordered global energy metabolism. Energy is as important as any vaccine or medicine. 2 billion people currently lack access to clean energy: they live in energy poverty and insecurity. International institutions, such as the World Bank and WHO, have repeatedly failed to make the connection between energy and health in their country work.

(continued — free registration required)

Dr. Horton gives examples of changes that we need to make at these three levels, such as changing travel habits at the personal level, designing new urban infrastructure at the national level, and controlling greenhouse gases at the global level. This introduction sets the stage for the in-depth analysis to follow.

While physicians should certainly read these, I also encourage others in the allied health professions as well as anyone with an interest in public health to read them as well. They are written in clear language and do not rely on advanced medical terminology or concepts. I will update this post with links to additional posts on the individual articles as I write them.

Source: Horton, R. “Righting the balance: energy for health”. The Lancet 2007;370:921. DOI:10.1016/S0140-6736(07)61258-6. Full text available; free registration required.

Squirrel Obstacle Course

From Greg Laden’s blog Evolution comes this cute video of a squirrel navigating an obstacle course. I’m always amazed at how intelligent other animals can be.

Alex, the Reasoning Parrot

I just read on CNN about a remarkable African grey parrot named Alex, who unfortunately has suddenly died. Parrots are well-known for their ability to reproduce human speech, but are widely considered to have no comprehension of the sounds they are copying. This is in contrast to animals such as chimpanzees and dolphins who have considerable intelligence but lack the physical apparatus (such as a voice box) to produce sounds resembling human speech. However, as the CNN article describes,

Alex’s advanced language and recognition skills revolutionized the understanding of the avian brain. After [animal psychologist Irene] Pepperberg bought Alex from an animal shop in 1973, the parrot learned enough English to identify 50 objects, seven colors and five shapes. He could count up to six, including zero, was able to express desires, including his frustration with the repetitive research.

Although one should always remain skeptical—could this be a complicated set of conditioned responses?—my cursory perusal suggest that Alex did possess some understanding of these concepts. His achievements are quite impressive and well beyond what most people would expect birds capable of doing. It’s a shame this remarkable bird has been lost.

For more information, see Wikipedia, Nature News, the Scientific American blog, or a 2004 Scientific American article (PDF) describing Alex. You can also watch video of Alex as part of the Scientific American Frontiers program on PBS (“Entertaining Parrots”, 2001).

Motorized Wheelchair Guided by Thoughts

A company called Ambient is developing a new wheelchair that is controlled by words the user thinks of. The system, called Audeo, uses a neckband to pick up signals in the nerves that control the larynx, or voice box. Obviously, this requires that the operator still has control of those nerves, though he doesn’t have to have control of the other muscles or the coordination that is required for speech. This has the potential to restore some mobility to those who have very little strength or coordination to make purposeful movements. And as this technology is refined, the potential uses are many: users could control other devices, such as a computer or television. If the “vocabulary” of the system is increased, the system could also function as an artificial speech synthesizer that could sense the words the user was trying to say and construct them directly. See New Scientist for more.

Below is a video demonstrating the system.

Potential Sighting of Yangtze River Dolphin

Image credit: Wikipedia.

Earlier this month, I wrote about the likely extinction of the Yangtze river dolphin, also called the baiji. Today’s New Scientist reported that a video shot by a Chinese man on 19 August may show a baiji, though it is difficult to tell from the quality of the footage. Even if it is a baiji, however, one animal is insufficient to repopulate a species. While it is theoretically possible to repopulate from a single breeding pair of animals, in practice, there is typically not enough genetic diversity for this to be successful. It seems likely that even if this sighting is confirmed, the animal is still “functionally” extinct, and that the inevitable “true” extinction has only been delayed by some years.

What has made this especially poignant is that I’ve been reading a book lent to me by a good friend: Last Chance to See, by Douglas Adams (the author the Hitchhiker’s Guide to the Galaxy) and Mark Carwardine. Published in 1990, the documentary is a companion to a BBC radio series highlighting endangered animal species. With his usual wit and humor, Adams narrates their journeys to find these unique creatures. I am just reading the chapter where the group is in China, searching for baijis. Sadly, their effort to draw attention to the plight of the baijis seems to have been futile; less than twenty years later the animal is already extinct or will be so shortly.

At this point, the only potential hope I see is for us to keep the baiji alive long enough (assuming the sighting was real) for us to develop the genetic technology to perpetuate the species. A different part of the book discusses the kakapo, a critically endangered flightless bird found in New Zealand. When Adams asks Don Merton of the New Zealand Department of Conservation about what he thinks the long-term prospects are, he replies:

Well, anything’s possible, and with genetic engineering, who knows. If we can keep them going during our lifespan, it’s over to the next generation with their new range of tools and techniques and science to take it from there. All we can do is perpetuate the during our lifetime and try to hand them on in as good a condition as possible to the next generation and hope like heck that they feel the same way about them as we do. (“Heartbeats in the Night”; p. 142)

It is now up to our generation to develop the science and cultivate the interest to preserve these creatures. And perhaps there is hope: the number of kakapo has apparently doubled since Adams and friends visited New Zealand; there are now eighty-six. And the book, too, lives on in a way; an interested reader maintains a blog following the status of the featured animals and others. (See his entry on the potential sighting of the baiji.)

“Woman Overjoyed by Giant Uterine Parasite”

From the Onion, a parody newspaper, comes this amusing take on a common event:

NEW BRIGHTON, MN—Immediately following a physician’s examination for her menstrual cessation, 37-year-old events planner Janice Crowley told reporters Tuesday that she is “ecstatic” with her diagnosis of a rapidly growing intrauterine parasite.

“I’m so happy!” Crowley said of the golf ball–sized, nutrient-sapping organism embedded deep in the wall of her uterus. “I was beginning to think this would never happen to me.”

(continue reading at the Onion)

While humorous, this article does remind us of just how unusual this physiological state is.