Eric Casaburi has spent his career at the intersection of fitness, hospitality, and health. Serotonin Active is the model he built to place medical-grade longevity medicine inside the venues people already trust.
Eric Casaburi founded Retro Fitness and scaled it into one of America's recognized gym franchises, growing the system past $156 million in annual system-wide revenue across more than 150 locations in 17+ states. He learned the economics of membership businesses the only way that counts: by living them, location by location, member by member.
The lesson that stayed with him was uncomfortable for the industry. People do not leave gyms because the equipment fails. They leave because the results do. For a meaningful share of members, no program design overcomes untreated hormone imbalance, metabolic dysfunction, or chronic under-recovery.
So he built the medical side. Serotonin Centers, founded from scratch, became a national medical wellness franchise offering hormone optimization, medical weight loss, aesthetics, and recovery therapies, earning a place on Entrepreneur Magazine's Franchise 500 list of top new and emerging franchises in 2025.
Serotonin Active completes the thought. Instead of asking people to drive across town for medical longevity care, it places a compact medical suite inside the venues where they already spend their time, fitness centers, luxury hotels, resorts, and golf clubs. It is the convergence of everything the first two brands proved, built as its own standalone franchise system under Longevity Brands LLC.
GLP-1 medications rewired how Americans think about weight. Hormone optimization went from taboo to table stakes for the over-40 athlete and executive. Recovery became a category of its own. The demand curve for medical longevity medicine runs straight through the venues where health-conscious, affluent people already spend their time: gyms, resorts, hotels, and golf clubs, and almost none of them are equipped to serve it.
Serotonin Active exists so that the operators closest to that demand, venue operators and the entrepreneurs who serve them, are the ones who capture it.
"Most venues offer an experience. The winners of the next decade will offer outcomes. Serotonin Active is how a great venue starts delivering medical-grade results, without becoming a medical company."Eric Casaburi, Founder of Retro Fitness, Serotonin Centers, and Serotonin Active
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