Al Roker spoke about his drastic weight loss and lifestyle changes on “Dateline” Sunday night, revealing an embarrassment stemming from his gastric bypass surgery – the “Today” co-host once defecated while covering the White House.

“When you have a bypass and your bowel’s been reconstructed, you think you’re pretty safe,” Roker divulged during the interview, which you can view in its entirety here. “And I probably went off and ate something I wasn’t supposed to, and as I’m walking to the [White House] press room .. I got to pass a little gas here. So I’m walking by myself — who’s going to know — only a little something extra came out.

“I pooped my pants,” Roker continued. “Not horribly, but enough that I knew. So I was panicking. So I got to the restroom in the press room, threw out the underwear, you know, and just went commando.”

The “Today” show co-host said the embarrassing experience was a wake-up call over how to eat after gastric bypass surgery.

“It told me to be very vigilant about what I eat,” he said, noting that the situation is common among those who have had the operation.

Roker recounted how he vowed to change his lifestyle eight years ago, when he tipped the scale at 320 pounds. He’s since dropped more than 115 pounds and is now a slimmer 204, according to "Today."

Roker said he was spurred to change his eating habits when his father, Al Roker Sr., was dying of cancer.

“One morning he said to me: ‘Look. You’ve got to promise me that you’re going to lose weight. We both know I’m not going to be here to help you with my grandchildren. So you’ve got to promise me,’” the weatherman said Monday on "Today."

The 58-year-old television personality started out with a strict diet, cutting caffeine, alcohol, sugar and gluten from his diet for a month. Roker lost 28 pounds in 28 days.

He noted that most who struggle with weight have more trouble keeping the pounds off than losing them.

Roker has written a book for those with the same struggles. “Never Goin’ Back: Winning the Weight-Loss Battle For Good” was released Dec. 31, just in time for those resolving to lose weight in 2013.