No to oatmeal, yes to 10-minute walks: How Serena Williams figured out what's best for her body

Serena Williams is a once-in-a-generation athlete. Even after retiring from professional tennis in 2022, she remains deeply in tune with her body. “My body speaks to me in ways that I don’t know if anyone else’s does,” she tells Yahoo Life.

It’s no surprise — she’s been conditioning it since turning pro at just 14. Now 43, the tennis star continues to prioritize her health and wellness, using tools like Abbott’s over-the-counter continuous glucose monitor (CGM), Lingo, to understand her body on a deeper level.

Williams does not have diabetes, but she's part of a wider trend. Nondiabetics are now using these monitors as an extension of more mainstream wellness wearables — like the Apple Watch, Whoop or an Oura ring — to gather information about their personal health. The first over-the-counter CGM, which tracks glucose levels, was FDA-approved in March 2024, and experts have predicted a rise in their popularity.

Williams’s interest was piqued. “I always saw them, and I wondered if they worked,” she says. “I was curious really because with my health background and always wanting to be in [good] health, I was wondering about glucose levels and what it meant, and how it could affect your body.”

A 2022 review of CGM use among nondiabetics found that some people were tracking their glucose levels not only to avoid becoming diabetic or prediabetic, but to improve their overall physical and mental health.

“I wanted to know how it was going to help my day-to-day,” says Williams, who had no specific health benefit in mind when she first stuck a CGM onto her arm. “I was a little bit wary about the results, and I was like: Well, I'll see what happens.”

Now, she’s using Lingo to track how her body responds to food, exercise and stress. Here’s what she’s learned in the process.

‘Everybody is different’

Williams has always understood that health isn’t one size fits all, but using Lingo has made that concept even clearer. “Everybody is different,” she says. “Two people can eat the same meal and have completely different glucose reactions.”

She’s tested this theory by putting her friends and family onto Lingo. Williams also sat down with her husband, Alexis Ohanian, to eat some of their favorite meals and see how their glucose readings varied afterward. “Things that affected my husband one way affected me differently, whether it was positive or negative,” she says.

Oatmeal was a staple — and a trigger

What surprised Williams most was learning that foods marketed as “healthy” aren’t universally beneficial. Unfortunately for her, her tried-and-true breakfast pick ended up triggering a glucose spike.

“I eat a lot of oatmeal in the morning,” says Williams. “That was my go-to every morning: oatmeal or a smoothie. But certain foods like that, that I considered my staples, spiked my glucose levels. So I had to kind of change how I thought about it.”

Changing up her breakfast routine has helped Williams be more mindful when it comes to what she eats. “Before, I’d eat meals thinking they were healthy, not realizing they were causing energy crashes later,” she says.

Syrup was also causing her levels to spike

Maple syrup, however, is something that she could’ve guessed wasn’t agreeing with her. “I generally don't like syrup, and my body was naturally telling me that. Then watching on my Lingo how my glucose spiked from it, it was just like, no wonder I don't like it,” Williams says. “If I have some sort of aversion to something, maybe there's a reason that I don't know. But I feel like with my monitor, I can get that reason.”

For Williams, this was just another reminder to trust her body — something she learned through her athletic career and personal health challenges. “My body literally talks to me,” she says. “I just have to listen.”

Using a CGM also takes the guesswork out of it, because Williams can check her levels after eating.

“Food … felt like a source of confusion: What's good, what's bad, what's causing these cravings?” she shares. “And now I feel like I understand exactly how my body responds to [something], whether it's specific foods or if it's activities and stress. … I literally have a better relationship with food.”

Walking helps

The 23-time Grand Slam singles champ may not be moving as much as she was in her heyday, but that’s OK. Small movements can have a big impact on her health, too.

“One thing I found really interesting is that a 10-minute walk can really flatten or lower your glucose spike,” she says. “It just sends you [a notification], like, ‘Go for a walk’ or ‘Stand up.’”

The Lingo app allows users to log meals and activities to track what has the greatest effect on their glucose levels. It then suggests ways to maintain more stable energy throughout the day.

Williams says that’s been a help when it comes to parenting her two daughters, Olympia, 7, and Adira, 1. “Improved energy levels means I can spend more time with my kids and play more with my kids,” she says. “I'm gonna need that energy with that little 17-month-old. She’s crazy.”

Knowledge is power

While Williams has had coaches, nutritionists and her own instincts to guide her health and wellness decisions over the years, she’s found a deeper level of understanding her body through monitoring it closely. “I love data, especially when it comes to my body,” she says. “We all want to optimize our living, so the more the merrier for me.”

Some experts have warned that the explosion of wellness wearables might lead to an overwhelming amount of information that users aren’t sure how to interpret. Williams says that isn’t the case for her and Lingo.

“I am very much not super-savvy on certain things and new things, but it was so easy to learn. I think that's why I liked it most,” she says. “I feel empowered.”

Williams acknowledges that some of the small habits that bring her energy up might seem like common sense, especially in her case. “As a professional athlete, you think you know this,” she says. “I wish I had this when I was on tour. My goodness, I think that would have helped me so much. And that would have been crazy to have even better results [on the court].”