Christian Bueno built his career by pushing his body past its limits — and for a while, it paid off. A lifelong fitness fanatic and personal trainer, the 33-year-old once looked like “Wolverine,” winning bodybuilding competitions and landing brand deals thanks to his chiseled physique. But after nearly a decade of heavy anabolic steroid use, “I wasn’t even able to take my shirt off because I literally felt like a dog who just had six puppies,” Bueno told The Post. The culprit: gynecomastia , or