For the next few months, Kate Tolo plans to follow a strict four-hour morning routine.
Starting at 6:30 a.m., she will take a barrage of tests: She’ll spit in a tube, check her temperature and measure her heart-rate variability . She will weigh herself and use a device to track her reproductive hormones. She’ll go for a 30-minute walk outside wearing a weighted vest, UV protectant facial mask and sun hat, then spend another 30 in her home gym.
At night, she’ll sleep with an acrylic device inserted into her vagina, which she said is intended to track blood-flow variations. On certain days, there will be blood, hearing and taste tests to take, stool samples to analyze.
“I am not a health person,” said Tolo, 30, sitting in her Los Angeles apartment. “I’m not a wellness person.”
But she is the girlfriend and business partner of Bryan Johnson, the 48-year-old entrepreneur and longevity obsessive. Clearly some of his habits have rubbed off.
Johnson, who sold his company Braintree to PayPal in 2013 for $800 million, has spent the last five years on a single-minded quest to reverse his biological age to 18. After a 2023 Bloomberg Businessweek article documented in detail Johnson’s diet, testing and medical procedures, he became the face of a burgeoning movement of men spending millions a year to turn back the clock . As his body has undergone dramatic physical changes, he has drawn scrutiny for his reliance on unproven and highly experimental treatments.
For her part, Tolo said she’s not chasing eternal youth. “I’m really doing it because I think that this is our path toward women being understood in the world and being seen.”
Her home experiment, which she and Johnson are broadcasting on social media, is aimed at mapping her biological data over the course of her menstrual cycle. Tolo hopes to build a baseline picture of her health: She’s young and in the prime of her reproductive years, but her periods are characterized by severe pain that has long bedeviled her.
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Kate Tolo will use a red-light machine. CHESSA SUBBIONDO FOR WSJ. MAGAZINE
Last week, Johnson announced that Tolo has endometriosis, after she underwent several experimental noninvasive tests. Tolo said she also learned she has polyendocrine metabolic ovarian syndrome, formerly known as PCOS, and adenomyosis, where the uterine lining grows into the organ’s muscle wall.
She plans to try out treatments that might alleviate her symptoms. The hope is that her experience can be used to inform future research and female healthcare more broadly. Women, she stressed, need to be studied and treated differently than men.
“Measuring and sharing openly your own data is great, but the concern is that it gets sold to other women as a path for them to do something, for which there’s no evidence,” said Jennifer Garrison , a neuroscientist and women’s health researcher.
Longevity influencer Kayla Barnes-Lentz, 35, cheered on Tolo’s effort. She has been posting her own personalized data for more than six years, following a regimen that includes spending at least one hour in a hyperbaric chamber and finishing dinner by 2:30 p.m. “I think more data is incredible,” she said.
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A detailed medical schedule outlines Tolo’s health and wellness regimens.
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Tolo and Johnson are skilled at capturing the public’s attention and leveraging it for business opportunities. Together they run the company Immortals, which includes their Blueprint supplement and product line, access to prescription medicine and a concierge medical practice. Immortals is funding Tolo’s wellness project, which is expected to cost $2.6 million annually, a figure that encompasses spending on equipment, testing and a dedicated team to keep it running.
While Johnson’s antiaging experiment captivated viewers, many turned skeptical of his endeavor once he began selling products, which now range from olive oil to GLP-1s. “I’ve made my money in life. I don’t need more money,” Johnson said. “Kate has never been driven by money.” Her transparency is meant to advocate for advancements in health research.
“Women of reproductive age were frequently left out of research because their physiology was considered too variable, too difficult to standardize,” Dr. Hillary Seger, who is part of Tolo’s internal care team, wrote in an email. “The result is a body of medical knowledge built largely without them.”
Tolo is hoping to shed more light on endometriosis and other conditions that affect women’s periods. While laparoscopic surgery remains the only way to definitively prove the existence of endometriosis, medical consensus is now moving toward treating symptoms based on a clinical diagnosis rather than a surgical one. Companies and research labs are working on new ways to diagnose.
Tolo will use a light-therapy device every morning to ensure she gets the same amount of bright-light exposure.
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“Endometriosis is one of those conditions that just doesn’t get the kind of research funding that it deserves,” Dr. Sara Szal, director of precision medicine and longevity at the Marcus Institute of Integrative Health at Thomas Jefferson University. The disease is present when tissue resembling the uterine lining grows outside the uterus. “I think of it almost like an autoimmune condition. It’s not a classical autoimmune condition, but the body’s definitely attacking itself.”
Szal likened the work of someone like Johnson to a public diary and cautioned that “more data does not automatically equal better health outcomes.”
At night, Tolo will sleep with an acrylic device inserted into her vagina, which she said is intended to track blood-flow variations.
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Despite his rigorous attention to his health, Johnson revealed earlier this month that he was diagnosed with autoimmune gastritis. “My stomach is eating itself,” he said on social media. While there are ways to manage the condition, there isn’t currently a cure. Johnson said he and his team are trying to “solve it.” The announcement sparked a wave of questions about Johnson’s earlier claims about being the “healthiest person on the planet” and where his care may have fallen short.
While he suggested online that his health habits and weight in his 20s contributed to the condition, he told The Wall Street Journal that he didn’t mean to imply a connection. “I have no idea if any of this contributed to my autoimmune condition,” he said, while remaining adamant that his regimen has helped, not hurt it.
Szal, who wrote a book called “The Autoimmune Cure,” said that the condition “can remain asymptomatic for years and is notoriously difficult to catch even with extensive blood work.”
Tolo’s introduction to Johnson came in 2016: She saw a quote of his featured in a newsletter about the evolution of humans and AI, and it piqued her interest. Tolo was working in fashion in New York, where she moved from her hometown in Queensland, Australia. Now she wanted to work for Johnson.
After years of outreach, she started as his executive assistant at his neurotechnology company Kernel in 2021. She quickly learned of Johnson’s antiaging quest, which at that point he was conducting privately. It was Tolo’s idea to take the journey public. The two became partners in that effort; a year-and-a-half in, their relationship turned romantic.
In the 2025 Netflix documentary “Don’t Die,” Tolo admitted that she used to frequent McDonald’s. Then she tried Johnson’s antiaging “protocol,” eating just 1,700 calories a day and taking 60 supplements. She’s been eating healthier ever since.
“I’m a reference point for her, but I’ve never suggested she do it,” Johnson said.
Tolo will use a machine to scan her face to see how her skin changes throughout her cycle.
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During an interview with the Journal in late June, a delivery of fresh meals arrived at her doorstep, the same ones Johnson tweeted about that day.
Immortals, which has more than 150 employees, declined to disclose how much money it makes. The company is on the verge of launching products for women: In Tolo’s bathroom was a stack of Immortals-branded vaginal microbiome tests, which it plans to soon sell. Through that lens, Johnson’s recent tweets recounting details from his and Tolo’s sex life and praising her vaginal health read not just as TMI, but as marketing.
Tolo said she isn’t trying to influence other women’s behavior. Neither, she stressed, is Johnson.
“He’s living in a cage. I’m going to join him in that cage,” she said. “This is not a normal way to live.”
Corrections & Amplifications: Bryan Johnson is not a vegan. An earlier version of this article incorrectly said he was. (Corrected on July 13)
