Bryan Johnson's Blueprint Turns to the Female Body: Kate Tolo Becomes the Measured Subject
Bryan Johnson
Bryan Johnson opens the video by naming what he sees as the core limitation of his longevity experiments. Over five years, he says, he and his team have "measured almost everything there is to measure," but every result has come from one male subject: himself. Because women go through large biological changes every month, across life stages, and in nearly every system of the body, he argues that a single male data set leaves a large gap. His answer is what he calls the team's most ambitious experiment so far. Kate Tolo, who is presented as someone who helped build Blueprint, will become, in his words, "the most measured female in history."
The Scope of the Experiment
Kate will spend several months doing exactly the same thing every day while the team measures hundreds of biomarkers across every phase of her menstrual cycle. Holding her routine constant is meant to isolate the changes that come from the cycle itself. Johnson gives these figures for the project:
- 1,900 biomarkers
- 16 biological systems
- 14.8 million data points
- More than 50 different devices
- An annual cost of $2.6 million
The physical footprint shows up right away. Kate says her entire apartment had to be redone for the experiment, and parts of the tour turn chaotic. Equipment doesn't fit where it's supposed to go, something falls over off-camera, and Johnson jokes that someone should check whether anyone was injured. Kate calls the reveal of her home "longevity clinic" one of her favorite moments of the process.
Preparation and the Emotional Arc
Asked how she feels, Kate says she has been "in preparation mode for the last 4 months" and is finally ready to start. She describes swinging between feeling unready, ready, panicked, joyful, and excited before arriving at readiness. Johnson stresses how compressed the timeline was. He says his own protocol took five years and a team of doctors to build, while Kate's was put together in 90 days.
Kate shows her schedule on a clipboard. Johnson admires how carefully it is designed and admits he has "nothing of the sort" after five years. His own routine, he says, lives entirely in his head. Kate describes her life now: every second is accounted for, and she has become "an experiment that is being observed at every moment." She has five different types of days, and Johnson notes that a single day involves more than 100 tasks. As he frames it, the practical challenge is structuring time to get through all of those tasks as quickly as possible.
Johnson says several times that watching someone else follow this kind of protocol feels very different from doing it himself. Kate says the sheer number of items means she can't even be present to all of them, and that no one but her will really know how much it involves. "At the end of the day, once I start, it's on me," she says.
The Overnight Arousal Device as a Case Study
The most detailed example in the video comes from Kate's morning routine. The first thing she does on waking is remove what she calls her "techno tampon," a device she sleeps with inserted and then tapes to her leg. Johnson explains its purpose: women, he says, have not been able to measure their nighttime arousal cycles, even though these happen in the female body every night, just as they do in men. Kate describes the device as the female counterpart to the erection monitor Johnson uses.
The contrast between the two devices becomes the video's main illustration of its broader point. Kate notes that she doesn't get a small wireless Bluetooth unit that offloads data automatically. Hers is "this beast," a very complicated device. One speaker sums it up: the male device is small, easy, and consistent, while the female version is gigantic, with "16 different things to change." They suggest this gap captures the whole project in miniature, showing how much more prepared the world is to measure men than women. The video adds that measuring women rigorously is extremely difficult under current scientific standards for randomized controlled trials.
The practical difficulties go beyond design. Kate used masking tape to secure the device overnight. She chose not to wrap anything around her whole leg because she worried about cutting off her circulation. By morning the tape had caused a problem visible on camera, prompting reactions of "Oh no," and the two agree the setup needs to be replaced. The episode shows how untested parts of the protocol still are at the start.
Johnson's Takeaways on Female Data
Johnson says that seeing how much Kate has to do has made him "very empathetic to a female's experience," even in basic practical terms. He poses two questions and answers them himself: how well quantified are women compared with men, and how much data exists on women compared with men? In both cases, he says, "not as much." He adds that the volume of work Kate is taking on suggests "we don't really have good intuitions about the female body."
He also questions society's priorities. People talk about ambitious projects like going to the moon, he says, so why isn't understanding the female body treated as a gigantic ambition too?
Acknowledging the Limitation
Johnson anticipates the obvious criticism: this is one person, Kate, and so it is a limited view. His response is that it serves as "an entry point" into the larger question of how to measure the female body at all. The experiment, as he frames it, is less a definitive study than a first attempt at a measurement problem he sees as underdeveloped.
Closing the Tour
The video ends lightly. Kate invites Johnson to try a vibration plate, and they joke about sleepover arrangements. The experiment itself is only beginning. Kate is ready to start, but some equipment still needs fixing, and the video leaves open what the months of data will actually show about how the female body changes across the menstrual cycle.
Hi friends. Over the past 5 years, my team and I have measured almost everything there is to measure. But my personal experiments have always had one major limitation. Me.
Everything we've done has come from a single male subject. Women experience dramatically different biological changes across every month, every life stage, and almost every system of the body. So this year, we're beginning our most ambitious experiment yet. Kate Tolo is about to become the most measured female in history.
That's an awkward leaf.
She's going to spend the next several months doing exactly the same thing every day while we measure hundreds of biomarkers across every phase of her menstrual cycle. In summary, this experiment will cover 1,900 biomarkers, 16 biological systems, 14.8 million data points over 50 different devices. The annual cost: $2.6 million.
My entire apartment got redone. This doesn't fit in here.
Watching someone else do this abide with me is very different than doing it yourself. Yeah, it's a lot.
There's 100 things like I'm not even present to it. Yeah. Like it's just like so much.
Kate, how are you feeling about this?
I feel like I've been in preparation mode for the last 4 months and I'm finally ready to take it on.
This has been a really big lift. I mean, it took 5 years and a team of doctors to build out my protocol and we've done yours in 90 days.
One of my favorite moments of this whole experience was revealing my longevity clinic to you. This doesn't fit in here. Everything's fine.
This tour has turned out to be a banger. Something just fell in there. You need to check if someone got injured.
You've seen me like oscillating between feeling not ready, ready, panicked, joy, excited, and then I feel like I'm finally ready. Look at my updated schedule.
It's so formal with the clipboard. You can see how beautifully designed this is. I've been doing this for 5 years, and I have nothing of the sort. It's all in my head.
Every single second is accounted for and I have become an experiment that is being observed at every moment. I have one, two, three, four, five different types of days.
She has in a given day 100 plus things to do.
Okay.
You're basically trying to structure your time to say how can you get through those things as fast as possible. Watching someone else do this is very different than doing it yourself.
Hold your breath.
The first thing I do when I wake up is I'm in bed and I have my little nook set up over here. Come have a look. I obviously have to take out my techno tampon. Come have a look at this device. So, I actually sleep with this inserted, this then taped to my leg using masking tape.
Women have not been able to measure their arousal cycles. And it happens in the female body every single night just like a man's body.
But this is Bryan's version. Yeah. Of an erection monitor. I don't have like the luxury of small wireless Bluetooth data offloaded thing. It's this beast. Like it's a very complicated device.
The level of readiness for the world to measure men versus women is captured in that. The device for a man: small, easy, consistent. For a female: a gigantic device, 16 different things to change. So if that kind of captures the entire project of like where the differences are between measuring men and women.
Yes, it is incredibly difficult to measure women in a rigorous way according to our current scientific standards for randomized controlled trials. So you can start to see just how difficult this gets to put into practice.
When I masking taped it to my leg,
What kind of tape do you have? It was just masking tape. It's not a good
Do you have a Oh. Oh no. What is it? Oh no. Oh no.
But I was like I didn't want to put something around my entire leg because I didn't want to cut off my circulation. And then I woke up in the morning and this was obviously... we need to get this replaced.
It's true.
It's just like
Yeah, it's a lot. There's hundred things like this,
you know, and like no, nobody's going to be able to know besides me, like the level of
Yeah.
At the end of the day, once I start, it's on me.
Yeah. Given the number of things that Kate is doing, I feel very empathetic to a female's experience. Even just like in very practical things like how well quantified are females relative to men, not as much. How much data is there on females relative to men? Not as much. Yeah, it's really really overwhelming.
Yeah, it's okay. It's okay. I understand.
Do you know why you're so excited about the female experiment? I feel like you got your hands into it and then you were like, "Whoa, there's this whole other world. Put this on your nose."
Oh, no.
It's very sore.
We talk about adventurous things like going to the moon and like doing big things, but like what about understanding the female body? Why isn't that a gigantic ambition for society?
Man, that's a lot. That alone is a lot, right? That it is.
You should be nice.
No, it's true. I would. It's significant. I don't do that.
Now, a lot of people will say like this is just Kate. It's a limited view. But you know what? It's an entry point to this larger thing of like how do you measure the female body? And given the number of things that Kate is doing, I think it's possible we don't really have good intuitions about the female body.
Do you want to come try a vibration plate? Abide with me.
This is amazing.
Well, that was pretty cool. Well, thanks for showing me around and you know this is fun. Can I sleep over?
Right. I would love that. Well, remember my agreement is that I get three nights of sleep in the same bed as you. If I complete this protocol, get three nights in the same bed as you.
Still forced me.
You can tell he didn't want to do it, but he's like, "Come on, do it. It will be an experiment."
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