Dateline's Josh Mankiewicz Lost 70 Lbs. by Cutting Carbs and Riding His Peloton for 148 Straight Days: 'I Felt Great' (Exclusive)

Mar. 15, 2025

Josh Mankiewicz before and after weight loss.Photo:Sean Mathis/Getty; Weiss Eubanks/NBCUniversal via Getty

Sean Mathis/Getty; Weiss Eubanks/NBCUniversal via Getty

TheDatelinecorrespondent, 69, opened up to PEOPLE about his impressive weight loss journey for the first time, detailing the commitment he made and why his latest journey was more successful than past attempts to lose weight.

Back in 1998, Mankiewicz lost 47 lbs. after trying the popular Atkins diet. He was pleased with the results but ultimately wasn’t able to maintain that over time.

But in May 2023, he decided to make some lifestyle changes after pressure from his doctor and his own frustration with his appearance.

“I didn’t like the way I looked. I didn’t like the way I felt. So I just decided to go ahead and do it,” he tells PEOPLE. “This wasn’t any particular diet, it was essentially just cutting out all of the things that we all sort of intuitively know that we’re not supposed to eat.”

Josh Mankiewicz.NBC News

NBC News

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Mankiewicz gave up bread, potatoes, pasta, desserts and fast food, among others. And instead of increasing his protein intake, he increased the amount of green vegetables he was eating.

“That seemed to do it,” he says.

The NBC reporter says that when his doctor first discussed his need to lose weight, she mentionedOzempic, an FDA-approved injection medication for people with type 2 diabetes. It’s one of the brand names for semaglutide — also known asWegovy— which works in the brain to impact satiety, and has been widely used as a weight loss aid.

“But giving myself a shot every week did not seem like something that I wanted to do,” he recalls. “And the idea of actually changing the way I ate seemed like a better idea. I’m glad that I was able to do it just on willpower. But sometimes people need help and there’s nothing wrong with that too.”

By the end of the year, Mankiewicz says, “I lost 70 lbs. and I felt great.”

“Now, I’ve pretty much permanently changed the way I eat because I’ve managed to adjust to this pretty well in terms of not craving any of that stuff that I used to love so much,” he says.

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“So I thought to myself, could I do 100 rides in 100 days? So I did. I ended up doing like 184 days straight, which was hard being on the road as much as I am forDateline,” he continues. “I didn’t really think of it as being difficult at the time. But generally, once I start on something, I finish it. And I was able to keep it going. It was good to get into a routine.”

Mankiewicz says that plugging into a community online — and in real life— helped him stay motivated.

Dateline’s Josh Mankiewicz and Keith Morrison.NBC News

Mankiewicz plans to continue his weight loss journey but is happy with what he has accomplished so far.

“I got a whole new wardrobe,” he says. “I had to throw out a bunch of stuff and that was kind of fun. And now when I turn onDateline, I only flinch at what the murderers are doing, not what I look like.”

Mankiewicz is approaching his 30th anniversary withDateline.In addition to the milestone, he’s also celebrating the release of his new true-crime podcast,Deadly Mirage,a six-part series that “examines how the murder of a California father unearthed deep secrets about sex, friendship, and religion that shattered carefully crafted illusions.”

“It’s got some mystery and it’s got some betrayal, and it’s got a love triangle. It also has some sort of what’s an essential element to aDatelinestory,” he says of the podcast, which has already released its first two episodes.

“It’s great to see people responding to it,” Mankiewicz adds. “It’s a new way of reaching the same audience, or in some cases reaching a different audience. And it’s great.”

source: people.com