Matt Kaeberlein, CEO of Optispan and longevity researcher, began testosterone replacement therapy in his early 50s after experiencing classic symptoms including low energy and reduced libido. Despite consistent strength training and balanced nutrition, he struggled to change his body composition, prompting medical testing that revealed low testosterone levels.

Kaeberlein emphasizes that standard blood tests measuring total testosterone can be misleading, as his initial results showed "low-normal" levels that didn't capture his actual hormonal deficiencies. After consulting with a more experienced physician and ordering specialized testing through services like Labcorp and QuestDirect, he discovered he had primary hypogonadism. He tried natural supplements and oral medications before settling on weekly testosterone injections.

Beyond medical specifics, Kaeberlein warns that TRT causes infertility and should only be considered by those certain about not wanting children. He stresses that testosterone therapy works best as part of an already healthy lifestyle, not as a standalone solution. "I think a lot of people have this experience where you feel like you're working really hard and there's just one piece that you're missing in the puzzle," he said, noting that TRT enhanced but didn't replace the benefits of proper exercise and nutrition.