Mark Hyman+

Why Rumer Willis tested her hormones through Function

“I didn't expect small changes to move a hormone number. I changed what I wore, what I ate, the products I used, and saw the numbers shift. It's wild to see how much my daily choices can impact my health. I tested my hormones through Function. You can, too.” - Rumer Willis

Rumer Willis Speaks on Fertility Health

“I'd have eight more kids if I could. That’s why protecting my fertility is one of the most important things to me. I want to know what's happening inside my body—before a problem shows up. But sex ed never gave us the full picture, and by the time most people get their fertility checked, it can already feel late. That’s why I’m taking my health into my own hands by testing through Function.” —Rumer Willis

How Rumer Willis Fights For Her Brain Health

Rumer Willis shares a vulnerable, honest look at loving a parent who’s living with dementia—and what it’s taught her about caring for herself in the process. She’s learned that being strong doesn’t mean choosing between missing who her dad was and being present with who he is now. It means holding both, while still taking care of herself in the process. It’s why she checked her own inherited risk through an ApoE gene test, given her family history. Check your health with Function. *Access ApoE testing for an additional cost.

The New Standard of Health: What Function Tests and Why

Your annual physical? It may include around 26 lab tests. But there’s a lot it could be missing. Function gives you access to 160+ lab tests annually, plus MRI and CT. @drmarkhyman breaks it all down with his Function co-founder Pranitha Patil and Dr. Danna Chung, Chief Medical Officer of imaging. They explain why chronic conditions like heart disease, cancer, diabetes, fatty liver disease, thyroid disease, metabolic syndrome, dementia, can develop for years before symptoms appear and why they built Function to change that. You'll learn what lab tests like ApoB, Lp(a), Fasting Insulin, hs-C

Your Headache Needs Context

We’ve spent years asking the internet health questions. Now AI can have more context about who’s asking. Function members can now connect their lab results and Clinician Notes to the AI tools they already use.

Mason's Story

True Story: Mason's hs-CRP had been high for months. His wife's was elevated, too. Diet and lifestyle changes didn’t work. His doctors couldn’t explain why. Then he connected his Function data to Claude. It pointed to something no one else had. If both of their levels spiked at the same time, the cause was most likely environmental. An inspection of their HVAC system confirmed active mold. Days after the repair, Mason's inflammation marker dropped. Function member since 2025.

Do you want Claude to act like your personal health expert?

Now you can. Connect @claude to Function.

What if ChatGPT actually knew your body?

Learn how to connect Function to ChatGPT.

The future of healthcare is already here. | Function x AI

Function co-founders Dr. Mark Hyman and Pranitha Patil have seen first-hand what changes when AI can securely connect with a deeper, longitudinal picture of your health with benefits for both patients and doctors. From personalized medicine and women’s health to the changing role of doctors and the privacy questions AI creates, this is a conversation about what healthcare could look like when AI finally has the context to understand the individual. But putting health data into AI raises an equally important question: who has access to it, and what happens to it? That’s why Function is prior

What actually is Diabetes?

Blood sugar changes can happen quietly. Check your health with Function.

What actually is Diabetes?

Blood sugar changes can happen quietly. Check your health with Function.

Tierra's Story

True Story: Tierra was fit on the outside from teaching yoga and bodybuilding. But she didn’t know what was happening inside her body. Function gave her a deeper look. Revealing simple things, like her blood type, and more serious signals like high LDL Cholesterol. So she changed how she showed up: more rest, smarter fuel, and more intention. To become the co-creator of her own healthy life. Function Member since 2025.

Holly’s Story

We need to talk about creatine.

Tiffany Lester, MD, Function’s Women’s Health Medical Director, explains why we need to talk about creatine. It’s one of the most researched supplements available. So why are women just now hearing about it?

World's Smartest Smoothie?

We teamed up with Erewhon to build a smoothie designed around what your body actually needs. @drmarkhyman walks us through how every selected ingredient earned its place, chosen using Function's data on the health gaps most people have in common. The World’s Smartest Smoothie? is only available at Erewhon locations. First-time members only get a $25 credit toward a Function membership with purchase.

His Wife Made Him Do It.

Forty minutes later, Craig understood why. The MRI with Spine can look for signs of cancer, prior stroke, fatty liver, herniated discs, and more. Because a parent knowing more about their health is a gift to the whole family. Now available to all Function members in 200+ locations.

Tova's Story

For Tova, every birthday past 39 is a milestone. That's the age her father died of cancer. Every year since has felt like both a gift and a reminder: never take your health for granted. That's why she gets an annual MRI. Because the goal isn't simply to live longer. It's having more time with the people she loves. Now available to all Function members in 200+ locations.

Ana's Story

True Story: Ana was a lifelong marathon runner. But she was battling muscle pain, twitching, brain fog, and crushing fatigue. Function helped uncover critically low ferritin and sodium, key markers that were missed for years. Now, she’s showing up stronger and more energized for the people she loves. Function member since 2025. Function gives you access to 160+ lab tests to get deeper insights into your health. Join today for $365/ year and take control.

Function Day Deal

Function day ends tonight. Don't miss the opportunity to join for 2 years at $499.* That saves you $231. You'll also get a $200 credit for your Annual MRI, and a $50 credit toward Add-On Tests. You can't buy time, but this is pretty close. *Billed upfront at $499.

What is cancer's biggest weakness?

You can't manage what you can't measure. Get deeper insights into your health with Function.

Why does hair turn grey as you age?

Not all signs of aging are visible. Biomarker testing helps uncover what's happening inside your body.

Why 'when' you eat matters

Meal timing may influence blood sugar, metabolism, and overall health. Biomarker testing can help provide a clearer picture.

Why are T levels in young men declining?

Concerned about low testosterone? Function helps you keep track

True story: Erin

Function day is here.

Function Day

True story a Function Team Member: My dermatologist said get labs. I already had 160+ of them.

Alan's Story

Biomarkers can help reveal how nutrition, sleep, stress, and exercise may impact your health over time.

Low Testosterone, Explained.

Concerned about low testosterone? Function helps you keep track