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.

first frame of animated GIF showing obesity rates over time
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.


Minnesota Is Now Smoke-Free



Map of American smoking bans
State-wide smoking bans. Credit: Mike Schiraldi.








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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.

Growing Body Parts

There has been some exciting work regarding the growing or re-growing of human body parts.

Some animals have an incredible ability to regenerate missing body parts—a classic example being some species of starfish. However, for the most part, it is not possible to regrow complex organs. In humans, damaged tissue usually is replaced by “generic” scar tissue, if it all. There are several reasons why humans cannot regenerate most body parts. For one, once cells become specialized, they often lost the ability to divide. Another reason is that arms and hearts and so on develop according to a specific pattern during embryonic development in the womb; there is no “program” for starting with part of a fully-developed structure and regrowing the rest. And furthermore, there is some evidence that the ability to regenerate has been sacrificed to avoid cancer. Cancer is essentially uncontrolled cell growth; many checkpoints that help regulate this may also prevent stem cells from recreating damaged tissue. Presumably, this balance reflects an optimum balance for the survival of our ancestors.

But scientists are working to augment this ability. As New Scientist reports, researchers in Japan were able to grow tooth buds in the laboratory, then transplant them to the jaws of mice where they developed into normal teeth; they even developed a blood supply. Also reported in New Scientist is the efforts of American researchers to grow new ligaments in the laboratory. Ligament injuries are quite common, and they tend to heal quite poorly.

Finally, LiveScience discusses regrowth of human fingertips after accidents, and mentions a few notable cases.

Retinal Implant Helps Restore Vision

Diagram of visual prosthesis
The major components of the new prosthesis. The small wearable computer is not included. Credit: Mark Humayun/AAAS. Source: New Scientist.

An article by Gaia Vince in New Scientist reports on a retinal prosthesis designed to help restore vision to blind people. After a prototype was successfully used in six people, further trials are set to begin. While cochlear implants are used to give deaf people some ability to hear, there has been no comparable, practical system for those who cannot see.

The system has several components. The user wears a pair of glasses with a built-in camera. The information is then transmitted to a wireless computer around the size of a mobile telephone that the user must keep with him. This computer processes the data, then transmits it to a receiver implanted in the user’s head. This is connected to a chip on the user’s retina. This all occurs extremely quickly, as discrepancy between perceived movement and visual changes would cause nausea and dizziness.

The device is still preliminary; the resolution is quite limited, naturally. But it is interesting that the brains of the patients seem to adapt to the limited visual input, and their vision improved over time. The article notes one patient’s observation:

At the beginning, it was like seeing assembled dots — “now it’s much more than that,” says Terry Bryant, aged 58, who received the implant in 2002 after 13 years of blindness. “I can go into any room and see the light coming in through the window. When I am walking along the street I can avoid low hanging branches and I can cross a busy street.”

Similar to the cochlear implant, an intact nervous system is required. This prothesis links with the ganglion cells at the back of the eye and the signals travel over the optic nerve to the brain. Damage to any of these components—such as damage to the ganglion cells, injury to the optic nerve, or stroke—will result in blindness that this prosthesis cannot correct. For that, we’ll have to wait for new technology.

Giant Microbes


Stuffed “animal” version of E. coli, from GIANTmicrobes.

My sister sent me a link to GIANTmicrobes, a web site that sells stuffed “animal” versions of many common microbes and more. There’s quite a variety there—aside from the bacterium E. coli, featured here, they have viruses, insects, protozoans, and even prions! (That’s my favorite.)

I think anyone in the health sciences would appreciate these. Most range in price from US $6–7.