Bryan Johnson's Blueprint protocol uses 20% caloric restriction, which lowers testosterone, so he supplements to keep it normal. He measures biological age through free testosterone index and reports a 20-year reduction in that marker.
One of the most frequent questions I get is, do I supplement testosterone? Yes, I do. Part of Blueprint is I'm on a 20% caloric restriction diet. Along with caloric restriction is you get lower testosterone levels. So I supplement testosterone to bring my levels back up to normal range. When we do these things, we track many things for safety and efficacy. One of these markers is free testosterone index. Over the past couple years, as we've optimized for caloric restriction, we've reduced my biological age by 20 years on that marker.
