Last week, biohacker Bryan Johnson shook the internet with a viral announcement: He’d been diagnosed with autoimmune gastritis, or AIG. “My stomach is eating itself,” Johnson wrote at the start of a lengthy social media post. The condition, he explained, is linked to his hyperthyroidism, which he was diagnosed with in his 20s. But without any clear symptoms, it took him another two decades to discover his AIG, finally being diagnosed this May at 48 years old. Johnson and his doctors eventually d