220.4-pounds Tyson hasn't fought professionally since 2006, and he weighed 220.4 pounds, the smallest he's been in the sport since 1997. The heaviest he's weighed in his career is 252 pounds. Tyson lost a total of 151 pounds over seven months in an effort to better handle his stress levels during fights. He started out by cutting back on food and then gradually worked his way up to 20 hours a day in the gym. His trainer, Kevin Randleman, says that when they first began working with him on this project, Tyson didn't even know what hyperbaric oxygen therapy was. They eventually showed him some research papers and that was enough for him to want to try it. Within days of starting the treatment, Tyson reported feeling much better and within a month, he had lost 50 pounds. He continued to lose weight at a rate of about two pounds per day until he reached his final weight on March 28, 1997 - just three weeks before his next fight. Since then, he has always been in good physical condition and has never looked or felt like he was carrying too many extra pounds. In addition to losing weight, Tyson claims that the treatment has other benefits for him.