Chiesa (14-4), who has been fighting at lightweight his entire career, missed weight for the first time this past weekend in Las Vegas. He weighed in at 157.5 pounds for his bout with Pettis (21-7) and told Helwani just how bad the weight cut was.
"I can't emphasize this enough, Ariel: I seriously thought I was going to die," Chiesa said. "Going through the first part of my weight cut, on Thursday, I really thought I was going to kill myself and I'm not exaggerating in the slightest."
Chiesa has been battling a foot injury recently and said it had a major impact on his ability to cut weight.
"Ultimately my body had nothing to give," he said. "When you can't do road work for a week-and-a-half, that's really hard on your weight cut. I came into fight week at 175 pounds, and usually I come into fight week at 169, 168 pounds. It was just too much for my body to handle.
"We cut weight for eight hours. We cut for four hours on Thursday night and I was up at 5 a.m. cutting weight on the day of weigh-ins [Friday] and my body had nothing more to give. I'm not exaggerating: I thought I was going to die. In the middle of the night before the Friday weigh-ins, I woke up and started having a panic attack. I broke down and started crying and was like, 'I think I'm going to die.'
"I've never felt like this. I made 155 my whole career without a hitch and it never feels good, but it's never like this, never in my life."
As of right now, the UFC has a 155-pound and a 170-pound weight division, but there have been calls for the implementation of a 165-pound weight class, moving welterweight to 175 pounds, which would then provide a 10-pound weight differential between the men's flyweight to middleweight divisions.
Chiesa is now the latest fighter to call for the introduction of this new weight class.
"I was already in talks with people around me. Win or lose, after this fight, I think I want to go up," he said. "A lot of people are trying to steer me to 170 pounds. I'm a big guy; people don't realize that. There's only one guy at 170 that's bigger than me, and that's Darren Till. I'm not a small guy. I can get up to 205 pounds and be athletic and be in shape.
"If [the 165-pound weight class] happens, it happens. If it does, I welcome it with open arms. I'm a big advocate for it. If they add 165 pounds, it would be heaven sent. It would be a blessing to a lot of us guys."
Chiesa also told Helwani he is taking legal action against Conor McGregor for injuries suffered April 5 after a UFC 223 media day at Barclays Center in Brooklyn. Chiesa was one of two fighters injured when McGregor threw a metal dolly through the window of a bus carrying several fighters and UFC staff.
Chiesa was hospitalized with multiple cuts, and his scheduled fight against Pettis that weekend was canceled and later rescheduled.
"The wheels are in motion," Chiesa said. "I'm doing what's been advised to me, and yes, there is a legal battle against McGregor."