Inside Larry Smarr's refrigerator this week was a stool sample that he planned to ship to a laboratory, which will send back a report of information about what's going on inside Smarr.
This monthly test is not part of his doctor's orders, nor is the plethora of mobile technologies that Smarr uses to track what's going on inside his body. But Smarr believes everyone should take charge of monitoring their own health, given how little time people tend to spend actually talking to their doctors.
Smarr may be an extreme example, but many people are turning to available technologies to gain knowledge about their bodies that they can use to optimize their health, beyond what information annual doctor's visits might bring.
"I am trying to respect my doctor by doing my part of the homework," said Smarr, 63, of La Jolla, California. Smarr is the director of the California Institute for Telecommunications and Information Technology, a research center at the University of California's San Diego and Irvine campuses.
Devotion to self-tracking has a name -- "Quantified Self" -- which is a website established by Wired co-founder Kevin Kelly and Gary Wolf, Wired contributing editor. Wolf's own website, Aether, says more than 12,000 people worldwide are members of Quantified Self Meetups.
As of Thursday, there were 873 people registered for the Quantified Self message boards, where people discuss the latest apps and research. The website has a list of hundreds of apps and tools available for tracking different aspects of your life, from mood to diet to sleep. The movement hosted the conference Quantified Self 2012 last weekend, with Smarr as a guest speaker.
In Smarr's view, it's absurd that we know the ins and outs of our cars, and invest in maintaining them, in ways that we don't with our bodies.
Imagine if you put water into your gas tank because you didn't read the manual, he said -- that's what some people are doing with their bodies.
"If there are key variables that I want that the insurance won't pay for, I will pay for it," he said. "If your car needs some preventive maintenance, you pay for it."
Tracking with your phone and other gadgets
Apps and small devices are getting ever more sophisticated in helping to track vital signs.
Smarr, for instance, wears a FitBit device every day to measure his caloric intake and how many steps he takes.
At night, he wears a Zeo, which sends a graph of the phases of his sleep cycle to his smartphone.
An app called Instant Heart Rate uses his phone's camera flash to measure pulse rate, and a second program called Stress Check measures the interval between heartbeats; irregularity means you are stressed, constant means calm.
A diet and fitness tracking app called SparkPeople has helped Michelle Jackson, 39, lose 102 pounds since March 2011.
She's not as serious about tracking all aspects of her body as Smarr, but admits that the few times when the app malfunctions because of an update, "I feel really almost debilitated," she said. "I'm very dependent on it."
Jackson uses the app to schedule all meals she plans to eat for the next week, starting with Sunday, but can make adjustments if plans change. The app suggests the calories, fat, protein and carbs to eat daily, and also helps her track the number of calories she burns as she records fitness activities.
Other apps exist to track how you feel. The mood app MoodScope uses an online card game to assess your happiness levels, and also offers tracking and comment features so you can see what might be behind your ups and downs over time. There's a social component, too.
The next hot area will be apps for mental and spiritual well-being, said Tim Chang, managing director of Mayfield Fund and an early venture capital investor in health tracking apps. Up-and-coming programs will include personalized training in optimizing things like stress and meditation.
In the future, phones may be able to get even deeper inside your head. There's a portable brain scanning system developed at Denmark Technical University that combines a low-cost EEG headset and a smartphone or tablet.