jawbone up Kazuhiro Keino / Flickr

The biggest design problem in medicine is frustratingly simple. 

When 660 doctors were asked to reveal their biggest complaints about patients, the number-one response was adherence.

As in, following the doctor's orders — like taking the pills to help your fever go down or going for jogs to help your heart.  

It sounds simple, but an estimated 50% of patients don't take their prescriptions as they should

That's because doctors can't really force patients do the things that will make them better. They can only make suggestions.

Put it into tech startup language, it's a matter of user behavior. Which means that it's a job for designers.

In a recent interview with Tech Insider, Fuseproject founder Yves Behar — whose portfolio includes everything from the new PayPal logo to the XO Laptop — told us how he's already designing for adherence. 

Behar says that wearable tech is still in its "infancy." Within the wearables sphere, fitness trackers have the biggest market share, like the Fitbit trackers, the Nike FuelBand, and the Jawbone Up, which Behar designed. 

As the technology advances, it could be especially impactful for preventing or treating lifestyle diseases. Leading killers like obesity, heart disease, and type 2 diabetes are controlled or worsened depending on a person's diet and physical activity. In fact, once developed countries get past infectious diseases like malaria, AIDS, and Ebola, it's these behavior-based diseases that are the number one killers.

Any design that can mitigate these factors could be a boon for healthcare. Design has the capacity to prompt behavioral change, and behavioral change is needed to fight these disease. 

"You could almost argue that all lifestyle diseases would benefit from an approach that is continual, and follows people through their journey, and not just a remedy," Behar says.

While Behar declined to discuss his future plans for wearables, he supplied a use case already seen in the Jawbone Up and other fitness trackers.

Yves Behar Business Insider

"We capture people's resting heartrate and we show it to them every day," Behar says. "Resting heartrate is the most important sign of heart health, and this is something that unless someone was watching your heart once a day, every day, or once a week for years, you wouldn't be able to see it change. Now you can you can see those numbers every day." 

Behar says that when he goes to the doctor, he wants them to see how much he's sitting, how much he's moving, and how his heartrate is looking.

Jawbone correlates those data points in its data-mining Smart Coach system. Then, using that data, the system gives users tailored advice. 

The medical research on wearables is still in its infancy. In a small April 2015 study, people given Nike Fuelbands " reported a significant increase" in their enjoyment and motivation of exercise over an 8-week period.

But a 2015 column in the Journal of American Medical Association found that "the gap between recording information and changing behavior is substantial, however, and while these devices are increasing in popularity, little evidence suggests that they are bridging that gap."

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What's more, a January 2014 market research study by Endeavour Partners found that over half of all people who bought activity trackers no longer use them, and a third of people stopped within six months.

The Up and its fitness tracker peers aren't the only products trying to crack the adherence code. The most Big Brother of these options is the Proteus swallowable "smart pill," which was just approved by the FDA. As MedGadget reports, the smart pills — which contain tiny digestible sensors — send signals to another sensor affixed to the body to monitor whether they've been swallowed.

The big question, then, is how wearables like the Up sustain the health gains that they help so much with in the first few months of use.

"To me, wearables are going to change healthcare," he says. "They're going to change our understanding of the human body, and I couldn't be more excited about it. From a human standpoint, I think it's the most important work we can do as designers."