Kate Tolo got her first period at 13—an experience she says left her lying prostrate on the floor, debilitated by cramps and breaking out into a full-body sweat.
When she told her dad why she was home from school early, she remembers him saying, “We don’t talk about that female stuff.” Then he walked away.
For most of her teenage years, that was how Tolo thought about her period—as something “you just didn’t talk about.” When she was in her early twenties and experienced extreme pain while defecating, sending her to the emergency room, a doctor suggested Tolo may have endometriosis, a chronic disease believed to affect an estimated 10 percent of women of reproductive age, according to WHO data.
Caused by an overgrowth of endometrium-like tissue (uterine lining), endometriosis is primarily characterized by extremely heavy and painful periods, as well as pelvic floor dysfunction, bowel issues, and dyspareunia (pain during sex). The doctor recommended Tolo have a laparoscopy, an invasive surgical procedure required to get an official diagnosis and remove endometriosis tissue. But she refused: “I wasn’t going to undergo an invasive surgical procedure, or cut myself open,” she says. “That just wasn’t an option for me.”
Then in early 2026, Tolo started developing a concierge health service with her boyfriend Bryan Johnson, the technologist-cum-multimillionaire-cum-biohacker known for his quest to become immortal via rigid self-optimization and wellness protocols. During a clinical intake, she shared her lifelong struggle with suspected endometriosis—and he became obsessed with finding a cure.
Since hard-launching their relationship last December, Johnson has positioned his girlfriend as “the female Bryan Johnson,” with Tolo adopting a rigorous self-tracking protocol to optimize her health. Using $2.6 million in funding from Immortals, the wellness company the two founded, Tolo is tracking more than 1,500 biomarkers from sources such as her blood, urine, and stool over the course of her menstrual cycle, via “an elaborately choreographed four-hour techno ballet of scratching, sniffing, spitting, scanning, stretching, gripping, vibrating, flexing, plucking, poking, pulling, peeing, and pooping,” as one recent Business Insider profile put it.
It’s a relatively new role for the 30-year-old Tolo, who worked in fashion marketing before becoming Johnson’s executive assistant and special projects director for Kernel, his neurotech company, in 2021.
Describing herself as an introvert, she says she was initially uneasy about becoming “the world’s most measured woman,” as Johnson put it in a video from last August. (He’s also declared her vagina’s microbiome to be in the “top 1 percent” of all vaginal ecosystems.) Prone to depression and anxiety, she had a panic attack on week two of the protocol, prompted by her internet going down while she was trying to conduct red-light therapy. “It’s a deeply uncomfortable experience for someone who doesn’t love a routine,” she concedes. “And so all of that pressure just really got to me.”
But to hear her tell it, it all serves a larger purpose.
“Even when every part of me, individually, is screaming ‘Make it stop,’ I can see myself pushing myself to the absolute limit of what is possible, mentally and also physically, in my body. Because I’m doing this for women,” she tells me.
One of Tolo’s primary interests is coming up with reliable diagnostic and treatment methods for endometriosis, a process that the couple has been documenting on their social channels. Though Tolo never underwent surgery and has never been officially diagnosed with endometriosis, so far the two claim they have diagnosed Tolo with the condition over the course of 42 days using noninvasive methods, such as a saliva and blood test and an endo-specific ultrasound. (A transvaginal ultrasound and an initial MRI originally came back clear.) Their next step is creating an organoid using cells from Tolo’s menstrual blood—“essentially, me in a petri dish,” as she explains it—to test various interventions, the results of which she will compare next to a more conventional biopsy.
For the past few months, Tolo has been collecting her menstrual blood in a cup and transferring it to a standing tube, repeating the process every few hours before shipping it off on ice in a Styrofoam container to be tested by a lab. (The couple will not reveal which lab they are partnered with, saying it prefers to remain anonymous: “The biotech world is sometimes a little bit more buttoned-up about how they go about things,” Tolo says.)
The blood collection process is grueling and laborious: “It’s like this race against the clock to get into the lab in time before the cells die,” she says. But she dreams of a world in which women would be able to collect their menstrual blood, then send it into a lab for testing in order to obtain an endometriosis diagnosis. “We want to confirm that women can do this without having minor surgery,” she says.
Endometriosis has historically been extremely difficult to diagnose, says Kristin Riley, the chief of minimally invasive gynecological surgery at Penn State Health. The disease can manifest itself in various ways, and the amount of endometriosis present in the reproductive organs does not necessarily correlate to the severity of the symptoms. And while physicians can make a clinical diagnosis based on patient self-reporting and ultrasound imaging, the “gold standard” for determining the presence of endometriosis is still surgery, says Riley. For this reason, it can take between five to 10 years to diagnose a case of endometriosis.
Over the past few years, the market has been flush with efforts to come up with simpler diagnostic tests. In the United Kingdom, for instance, Endotest, marketed as the world’s first commercially available saliva-based diagnostic test, was recently approved for temporary clinical use. The test examines biomarkers called microRNAs that may indicate the presence of endometriosis in a patient’s body. But though the test shows “promise,” Riley says, it’s unlikely it will be approved for mass distribution anytime soon in the United States, or that physicians will start using it in lieu of laparoscopy.
Physicians who treat endometriosis regularly are also skeptical that Tolo and Johnson’s methods will yield helpful results, given the extremely limited sample size. “There’s something to be gained from all different types of research, but before something can be adopted widely into practice, it has to be really well proven,” says Ilana Ressler, an ob-gyn at Illume Fertility in Connecticut. In order for Tolo’s project to be successful, the results “would have to be applicable to a general population, and not just one person.”
On social media and in our discussions, Johnson has framed his interest in curing endometriosis as purely a labor of love. “I’m desperately in love with Kate,” he says. “[I] want her to be happy and well, and it’s been so many years she’s had to live with all this pain, and I just want to help do this for her.”
Some of the couple’s efforts to highlight the struggles of living with endometriosis, such as an X post of Johnson standing between Tolo’s legs as she gets a vaginal ultrasound, have raised eyebrows for skirting the bounds of tastefulness. It’s a critique that bothers Johnson. “Why can’t we talk about these things openly?” he asks when I bring it up. “Why does this have to be so political? Why can’t this just be seen as a loving gesture?”
Tolo, however, whose background is in marketing, gets it. “From day one, I’ve seen my job as: How can I help the world understand Bryan and who he is?” she says. “I probably missed how important it was for me to be a part of that story from the beginning. [But] now, I think people understand the both of us better than they ever have.”
Tolo’s public quest to highlight a debilitating but poorly understood reproductive health issue, as well as Johnson’s fervent support, have translated into a positive shift in public perception, particularly toward Johnson himself. Since he started advocating for extreme anti-aging procedures, such as intergenerational blood plasma transfusions or penile rejuvenation injections, Johnson has long been derided as an out-of-touch Silicon Valley weirdo. Yet his quest to treat his girlfriend’s endometriosis, coupled with his obvious affection for Tolo (at multiple points during our conversation, he compares their relationship to that of Abigail and John Adams), have endeared him more to the public. “I’m so happy Bryan found his soulmate and proved true love exists,” reads one representative tweet.
True to form, Johnson has quantified how going public with his love for Tolo has contributed to this shift. “I built a couple of AI agents and I scraped all of the social commentary about me over the past five years,” he told me. A few years ago, he estimates, it was 80 percent negative; now, he says, it is “70 to 75 percent positive.”
Going public has also, undoubtedly, been a boon for Tolo’s profile: Since April 2026, when Johnson posted about Tolo’s vaginal microbiome, she has more than tripled her Instagram following, according to data from SocialBlade, a firm that tracks creators’ influence.
When I ask if the couple plans to funnel this surge of attention into, say, developing a product for their company, Immortals, which provides personalized health concierge services, Johnson and Tolo demur. But it’s worth noting that Immortals has forayed into women’s health and wellness products, including topical estradiol for postmenopausal women and tretinoin cream to combat the signs of aging. And since the approval of Endotest in the UK, there’s been increased interest in the burgeoning endometriosis diagnostic test industry, which a recent GlobalData report estimates will be worth $2.5 billion by 2034.
Tolo says that it’s simply too early to tell whether a menstrual blood diagnostic test is feasible, noting that it will take the couple at least another eight to 12 months to conclude all of their research. But she concedes that the ideal outcome would be bringing an endo diagnostic blood test to market. For the time being, however, she says, “our ultimate goal is to make as much as we can about female health public so we can spur the entire industry” to develop noninvasive diagnostic tests.
Among the other experiments Tolo is subjecting herself to are tracking her nighttime erections with a small device she calls a “techno tampon” and using a sauna to see how her menstrual cycle would be affected by extreme heat, with Tolo taking a temperature-tracking pill before trying to push her core temperature to a brutal 102.4 degrees.
After 25 minutes in the sauna, Tolo started feeling nauseous and having headaches. Johnson says he became concerned about her and encouraged her to step out, but she refused. “She’s very sincere when she says she’s doing this for women,” he says.
Tolo stays quiet. She’d just gotten an x-ray of her abdomen to ensure that the tracking pill hadn’t gotten lodged in her stomach, and she seems a little bit more depleted than she had in our past conversations.
I ask what it felt like to be in such an intense physical situation, and what was going through her mind. She answers almost immediately.
“I wasn’t getting out of there. There was no other option,” she says. “I felt sick at times. I didn’t know how reasonable or logical I was being, if I was losing my bearings, if I was going to pass out. But I wasn’t going to waste the opportunity to do something on behalf of half the population.”
OK, I ask, but did it have to be her? Did Kate Tolo’s body have to become the most tracked female body in the world?
“I don’t know what other individual woman would have the time, the access, the level of privilege to be able to take this journey,” she says. “So I’m taking myself out of this and saying from a humanity perspective, in 2026, this is the right thing for this human in this body to do, in service of all the other women out there.”
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