As I stepped on the bathroom scale, my life flashed before my eyes. I looked into the mirror and saw a graph, magically overlaid on my reflection. The red line plotting my weight over the last year looked like the Dow Jones average, with little bumps during the Thanksgiving and Christmas eatathons. It was a sobering image.

That system, called NetWeight, is the invention of MIT Media Lab researcher Brad Geilfuss. With it, Brad argued a fundamental thesis: the way to revolutionize medical practice is by connecting our bodies more directly to the medical system. Since most of us are a captive audience for a few minutes a day in the bathroom, he started there. The scale was a networked sensor. The mirror gave you an “inner view”: it contained a Silicon Graphics computer and a video projector that overlaid live graphics on your reflection. The weight graph could appear on your beer belly.

Before you run screaming from the littlest room in your house with visions of Big Brother watching your every excretion, let’s think this through.

The problem of staying in touch with our health goes far beyond just monitoring flab. For example: there isn’t a person on the planet who has seen a simple, cogent picture that traces the health of his or her heart over the last few years. This can have grave consequences.

Americans suffer 1.5 million heart attacks each year, but only about 10 percent of victims receive timely treatment. When you have an attack, you need an injection of an anticoagulant within an hour or two. Wait longer than that and the drug may do more harm than good. Of course, by then it’s often moot. The muscle has begun to die. In any event, it’s far more expensive to care for someone who has been felled by a heart attack than to nip one in its early stages.

Why do most heart attack victims fail to get treatment in time? The biggest source of delay, it turns out, is that people are disconnected from their bodies. We ignore symptoms. Technology that either exists now or could soon be developed offers a solution. For instance, it should not be too hard to build a wristwatch for high-risk patients that has the cardiological smarts to detect a heart attack, which is about as subtle as a 7.0 Richter quake. The watch would send the right blip to the right place, summoning medical attention and greatly increasing the chance that the patient gets the right treatment in time. At the least, it might flash an alarm: Four hours to live! Call this number.

Of course, heart problems are about much more than a few critical moments: there is a long period of unhealthy living that leads into the risk zone. The trouble is that most people are flying blind. Our sick-care system (and that is what it should be called, since most folks only use it after blowing a gasket, after the damage has been done) is built on the quaint notion that you’ll visit the doctor once in a blue moon and provide a pinprick of data that somehow enables the physician to keep you healthy. But once your body is online, just getting dressed in the morning will activate a “body network” of jewelry, apparel and appliances that collects more vital data every day than your doctor sees in a year. You may be able to see the early warning signs of heart disease in graphic detail when there’s plenty of time to do something about it-and the sporadic medical checkup will go the way of the dodo.

The last time vital-sign monitoring was substantially improved, the result transformed hospitals. Around 1863, Karl Wunderlich proposed a standard medical chart that would hang on the end of a hospital bed. His chart showed temperature, pulse, and respiration data, so that a physician could monitor a patient’s progress at a glance. That basic tool probably had more impact on the quality of hospital care than anything other than drugs and antiseptics. The application of new technologies to the convenient tracking of an individual’s health status promises even greater change today.

The personal vital-sign monitors in the coming wave are wearable, networkable, even fashionable and fun. The implications of these inventions go far beyond hospital critical-care rooms. Some signs of the times:

• MIT researchers run the Boston Marathon sporting fanny-pack body monitors that transmit their stats (pulse, stride, body temperature) to the Internet. Similar technology was tested by climbers on Mount Everest.
• Olympic sprinter Michael Johnson wears ultrasmall accelerometers that analyze the kinematics and physiology of his 400-meter dashes. Champion bicycle racer Lance Armstrong uses new bike-mounted sensing systems to radically improve his performance.
• Companies like FitSense and Nike have introduced watches with radio links to their shoes. The watch is a “dashboard” that precisely tracks how far you run; FitSense’s watch even transmits the results to the Web.

Some technologies are exotic. The Media Lab marathoners swallowed a horse pill that measured internal temperature and radioed the results to a belt-buckle receiver. Since the circuit is cast in a plastic shell that keeps it from reacting chemically with the body, approval from the U.S. Food and Drug Administration was a breeze. John Glenn used the same pill sensor system in his latest space flight. That pill lent itself to a classic demo: place a graduate student near a computer, feed her a pill, and observe the temperature graph on the screen. Then pour some piping hot coffee into her and watch the graph go up. Then some ice cold beer. Then some piping hot coffee…

This cycling is much like what one observes in marathoners. Body temperature goes up for the first few kilometers. But at about kilometer 30, temperature starts to fall off a cliff: having burned up all the fuel in the furnace, the body begins to get cold. (On closer inspection, the temperature moves up and down, with periodic dips every few kilometers. Each dip turns out to be a cold swig of Gatorade.)

MIT student Maria Redin gave the technology a romantic twist. Working with Ronald Winston, president of the Harry Winston jewelry company in Manhattan, she created the Heart Throb Brooch, a lavish diamond-and-ruby pin. The rubies glow with every heartbeat. A transmitter carried in a clutch purse or built into an Armani eyeglass case sends the signal to the Net.

Flashy jewelry suggests a way to turn health monitoring into a killer app (no pun intended). Jewelry touches (even pierces) the skin in places like earlobes, necks, wrists and fingers. Often it is worn near the heart. So it is well situated to monitor vital signs. Jewelry also can be expensive, which may be seen as a feature, not a bug: with all those Winston diamonds, you’ll hardly notice the cost of the technology. And jewelry is an enticement to accessorize. It invites a networked ensemble, a set of sensible jewels that form a little internet around the body. Finally, jewelry exists to communicate. It signals your status and tastes to partners or potential mates. (Redin conceived of the Heart Throb in a “His & Hers” configuration: one spouse might wear a sensor, the other the jeweled “display,” and when the two drew close at a party, one would glow like a Christmas tree.)

And it won’t stop there. High-definition television may finally find its place in retinal implants (wouldn’t you like better night vision or eyes with 200:1 zoom?). Clearly, the coming decades will see startling advances in human body networking: we will live through revolutions in wearable, edible, implantable, sense-able, fashionable, tasty ensembles of devices. Within 10 years we will probably take the notion of placing our bodies online for granted.

Patients going in for elective open-heart surgery are asked two questions: (1) do you have a spouse/lover/confidante? (2) do you regularly hang out with a group (church/synagogue/bowling league)? Six months later, those who answer yes to both questions have a seven-times better chance of being alive. This suggests that technologies that are connective, that help us better see ourselves, and help us share that picture with those close to us, can really pay off.

To our grandchildren, the notion of Doctor Jellyfinger collecting a pinprick of data will seem as archaic as treating cholera with leeches, and an absurd basis for a health-care system. In their world, vital signs will be sampled casually and continually by sensor-laden garments and jewelry. They will wonder what a regular checkup was, or how their grandparents lived in a world in which they knew more about the state of their cars than about their own bodies. This isn’t just an ounce of prevention, but gigabytes of it, for a health-care system that provides most Americans with 1930s-era treatment.

It’s time for a new bathroom scale. Got the picture?