What sitting all day does to your brain and body | Keith Diaz | Your Body on Tech

**Manoush Zomorodi** (0:03)
You're listening to TED Talks Daily, where we bring you new ideas and conversations to spark your curiosity every day.
Hello. No, I am not Elise Hu. I'm Manoush Zomorodi. I'm a journalist, an author, a two-time TED speaker, and you might recognize my voice because I host the TED Radio Hour podcast over on NPR. So why am I here? Well, this week, I am taking over from Elise to bring you something a little special, a series of episodes all about how you can live a healthier life in our high-tech era. Because in April, I had the honor of guest curating a session at the TED 2026 conference, and I packed it full of speakers whose work I have been obsessed with and who I think will make you think differently about your body, how you use your technology, and what is keeping us human in this digital age. So every day this week, we are bringing you one of these talks from my session, followed by a conversation with these incredible speakers to go deeper. Really, truly, they are amazing.
Let's begin with a feeling, okay? That end of the day, so drained, can barely think, exhausted feeling that comes after spending hours on our devices. Physiologist Keith Diaz knows that feeling.

**Keith Diaz** (1:31)
I was so tired, exhausted actually, but I hadn't used my body at all.

**Manoush Zomorodi** (1:36)
I met Keith in 2023 when I came across research he'd done in his lab at Columbia University Medical Center. This is where he studies how lives spent mostly sitting and looking at screens affects our health.

**Keith Diaz** (1:51)
We are living in the most sedentary era in modern history.
What scientists have found is that being highly sedentary increases your risk of diabetes, cancer, dementia, heart disease, and ultimately early death. This is true even if you exercise regularly.

**Manoush Zomorodi** (2:11)
Yeah, it's awful.
But Keith has spent his career trying to figure out the minimum amount of movement that human body needs every day so that you don't die an early death. Our teams at NPR in Columbia ended up partnering to see if we could get his research out into the world. We wanted to find out, could people take movement breaks throughout their day and take back their health from their sedentary screen filled lives? And we ended up creating one of the largest citizen science studies ever. If you follow me on social media, you have probably seen me post about this study. We called it Body Electric, and very recently, I put out a book by the same name, which has these findings at the heart of it. Keith explains the study and what you need to maintain your body on a daily basis. And then I joined him to talk about what it takes to balance our biological needs with all the conveniences of modern life, so that we're not living some drained, tired version of ourselves. All that right after a quick break.
And now our TED Talk end conversation of the day.

**Keith Diaz** (3:30)
My favorite job ever was as a summer camp counselor, where it's basically paid to play games with kids all day. We played capture the flag, running bases, dodgeball, went swimming in the pool every day. And at the end of the day, I'd be tired, but in a good way. Not mentally drained, but physically tired. A satisfied kind of tired, where I'd use my body to complete a hard day's work. Flash forward, and my job today looks very different.
Even though I'm an exercise scientist, I don't get to actually do any exercise at work. Instead, my days consist of staring at a computer screen and sitting in countless meetings. The transition for me to office work was jarring. I no longer had those same feelings of satisfaction at the end of the day's work. I was so tired, exhausted, actually, but I hadn't used my body at all. And this shift that I experienced, I'm not alone in feeling. We are living in the most sedentary era in modern history. In a single year, the average adult now spends a full 187 days, over half of the year sitting or physically idle. The bad news is that our bodies weren't designed for this. I know because I've spent my career as a scientist studying the harms of being highly sedentary. And what scientists have found is that being highly sedentary increases your risk of diabetes, cancer, dementia, heart disease and ultimately early death. Worse, this is true even if you exercise regularly. To put it simply, being highly sedentary, as many of us are, is toxic. Let's start with the healthiest people among us to use as an example. In one study, when highly trained endurance athletes were forced to bed rest, their aerobic fitness levels dropped by about 20 percent in just three days. What took them months to build was erased in a matter of a long weekend with no movement. This isn't unique to highly trained endurance athletes. If you took a regular, typical healthy adult and forced them to 40 days of bed rest, their heart would show changes similar to 50 years of aging. Now, this isn't about missing a workout or two. Exercise only makes up a tiny fraction of your day. The toxicity comes from when movement begins to disappear from your life. And this begs the question, why isn't exercise alone enough? A part of the answer lies in our muscles. Our muscles are more than just a machinery that power movement. They're also really important for regulating things like our metabolism. Let's use blood sugar as an example. Our muscles are like sponges for blood sugar. When we regularly use and contract our muscles, they're like a moist sponge, soaking up the sugar from the bloodstream. But when we don't regularly use and contract our muscle, like a dry and shriveled up sponge, not really good at soaking up anything. But here's the key, when we exercise, it rewets the sponge. But eventually, that sponge dries out. If you get little to no movement the rest of your day. So what do we do?