But Sinclair, a 54-year-old professor in the Department of Genetics and co-director of the Paul F. Glenn Center for Biology of Aging Research at Harvard Medical School, isn’t rigid about everything. 

He doesn’t exercise every day nor sleep more than six hours a night usually, he tells GQ in a recent interview (standard guidelines recommend between seven to nine hours of sleep each night and 150 minutes of moderate-intensity exercise per week). 

Still, he says his regimen has helped him stay biologically 10 years younger than his age—underscoring a modern phenomenon called reverse aging by combating age-related disease and decline. 

“I think a lot of us think that when you’re in your twenties, you’re impervious to aging and illness, and what we now know is that the epigenetic clock starts ticking from birth and that what we do in our twenties does affect our ultimate longevity,” Sinclair tells GQ. 

While research on delaying and reversing aging is relatively new, experts say it concerns your epigenetics. Longevity experts have outlined the 12 hallmarks of aging, including epigenetic alterations, cellular senescence, and chronic inflammation. Lifestyle factors and other interventions targeting one or more of these hallmarks may delay the aging process. 

“Biological age is a much better representation of health status than birthday candles,” Sinclair previously told Fortune. “Birthday candles don’t tell you how well you’ve been living and they certainly don’t tell you how many years you’ve got left.”

He believes that we’ll one day be able to turn ourselves back 20 years. “I don’t see any reason why that won’t be possible,” he continued. “It’s just a question of when.”

So what is Sinclair’s secret to aging well and staying young? He began working on it in his early thirties. Here are the three ways the longevity researcher got started: 

Taking resveratrol

Sinclair swears by resveratrol, a polyphenol or natural antioxidant commonly found in berries, peanuts, and red wine. He consumes it in a supplement form each morning with “a couple of mouthfuls of yogurt.” Along with the yogurt, Sinclair has green matcha tea—full of polyphenols such as ECGC catechins. 

Research suggests polyphenols’ antioxidant properties help strengthen the gut microbiome, decrease the risk of tissue damage, improve mood, and increase heart strength. 

Sinclair takes the micronutrient as a supplement, which, if taken in high dosages, poses a risk for side effects like nausea and vomiting. According to the Cleveland Clinic, you’re more likely to benefit from the whole food source rather than the micronutrient in supplement form. 

Sinclair tells GQ he’s prioritized his morning polyphenols for roughly 15 years.

Skipping breakfast

Sinclair skips breakfast, and intermittent-fasts by waiting between 16 and 18 hours between large meals—a trend championed by many in the C-suite. 

“That’s basically having a very late lunch or large dinner,” he tells GQ, although he says starting this regimen younger can be risky and cautions against malnutrition and starvation. 

Research shows intermittent fasting may lower the risk of diabetes, heart disease, and dementia—many cornerstones of aging. But fasting is not for everyone and can pose a health risk, not to mention trigger those who struggle with eating disorders or disordered eating. Without being too strict, there are also ways to fast that may work for you. 

Experts recommend starting small, making meals highly nutritious, and staying hydrated. 

Avoiding sugar 

Sinclair started turning down sugar (and meat). He focuses on a plant-based diet; a typical dinner consists of rice, almonds, and couscous. 

“I rarely, rarely eat anything other than plant-based and nut-based foods, including milk,” he tells GQ. And while a glass of wine has been a staple of the Mediterranean diet, Sinclair has said goodbye to the nightcap. 

“I’m off dairy and I’m off alcohol as well. Very rarely will I eat any or drink any of those things, but on occasion for a celebration or whatever I’m happy to do that, but that’s what I focus on.” And he admits he has the “occasional french fry.” 

Within months, he says his diet has “made a huge difference to my blood biomarkers and epigenetic age.”

A plant-based diet is associated with health benefits such as lowering the risk of diabetes, dementia, obesity, and high blood pressure. Plant-based foods also help lower the chances of cardiovascular disease. Similarly, consuming excess sugar, specifically added sugar in highly processed foods, is associated with diabetes, obesity, and heart problems, according to Harvard Health. 

“When I switched to this new diet, I got my memory back as well. I was unable to remember phone numbers and key codes easily, and now it’s simple,” he tells GQ. “So I got back to my 20-year-old brain. I just thought it was old age, but it wasn’t, it was my lifestyle.”