LONDON >> Just before lunch on a recent Monday, Jamie Oliver wrapped an apron around his dad bod and started mashing mint and broad beans with a mortar and pestle, which has long been his favorite kitchen tool.

That adorable mop of hair he had 20 years ago when he slid down a banister and splashed into popular food culture as the Naked Chef is cropped now. At 44, Oliver comes off more like a pleasant, world-weary high school teacher than the arrogant jokey bloke everyone wanted to hang around with back when he blew up food TV.

And are those bags under his blue eyes?

“Sorry, darling,” he said as he seasoned a fillet of Dover sole. “I’m a bit tired.”

The day started before 6 a.m. He dropped his children at school, then made his way to the refurbished North London warehouse that serves as his headquarters. After feeding a reporter lunch, he had to meet top officials from Liverpool, Manchester, Birmingham and London who were coming by the office to hammer out a plan to halve childhood obesity rates by 2030.

It didn’t help that he and his wife, Juliette, who goes by Jools, had exhausted themselves over the weekend moving into a $7.2 million 16th-century Tudor mansion not far from his parents’ pub in Essex. (They’re keeping the eight-bedroom North London town house.)

Granted, that kind of move is a little different from asking your friends to help you muscle a mattress into a studio walk-up. Still, moving is moving, especially with five children, including a feverish 3-year-old who spent the night “jumping around me like a rattlesnake,” Oliver said.

It wasn’t just a bad night’s sleep, a new house and a packed day that weighed on him. “I have probably been pushed to the edge of my capacity over the last four years,” he said.

In May, the Jamie Oliver Restaurant Group went into administration, a form of bankruptcy protection. The company, according to some accounts, owed creditors nearly 83 million pounds (about $100 million). Oliver said he tried his hardest to keep the business alive. But after closing some restaurants, injecting the equivalent of more than $15 million of his own money into the company and searching for a new investor, he gave up. In all, he shuttered or sold 25 restaurants, putting more than 1,000 people out of work.

Closing his first restaurant, the fashionable Fifteen in London, hurt the most. He had opened it in 2002 to train unemployed young people, many from difficult backgrounds, how to prepare tasting menus, make fresh pasta and run a proper dining room.

“That was the hardest thing I’ve ever had to do,” he said of the closing. “Just terrible. Awful.”

It would be easy to see a touch of Icarus in Oliver, or to view his saga as some sort of life lesson from an overachiever. But it’s too soon for deep reflection, and that’s not really his strong suit.

Oliver is, by most accounts, an optimist and, by his own account, what the British call a grafter — someone who just puts his head down and works, whatever the circumstance. That’s what has gotten him this far.

“I always graft it,” he said. “I put the effort in.”

OLIVER LEARNED that hustle early, growing up in the Cricketers, the pub his parents still own in the village of Clavering. “I was ducking,” he recalled. “I was diving. I was washing cars, washing toilets.”

He was a lousy student, but he knew his way around a kitchen, so he went to culinary school. He was a sous-chef at the River Café in London when a BBC crew showed up to shoot a documentary. A smart producer saw how much the camera loved him.

“The Naked Chef” debuted in 1999 on BBC Two in Britain, and a year later on the Food Network in the United States. The camera work was shaky, and his style kinetic. Oliver froze up when speaking directly to the camera, so producers hung just off to the side and asked him questions.

By current digital standards, the show looks like something your brother the aspirational cook might shoot on his iPhone. But back then, it felt fresh, unscripted and sexy. Oliver whipped around town on a motor scooter (which now sits in front of his headquarters) and slid down a spiral banister to let friends into his East End flat to help him cook.

He stuck his fingers into limes and lamb, and tossed every salad with his hands. He ushered a generation of young men into the kitchen, and taught them expressions like pukka (excellent) and lovely jubbly (also excellent).

Oliver secured an endorsement deal with Sainsbury’s, the second-largest supermarket chain in Britain, that would last 11 years and earn him close to $12 million. He wrote a bestselling cookbook. It was a lot for someone in his early 20s.

In 2008, he opened his first Jamie’s Italian restaurant with help from his mentor, Italian chef Gennaro Contaldo. The idea was to disrupt midmarket dining. The meat had an animal-welfare pedigree. Butter was organic. Wages were decent and prices affordable.

The restaurants were packed from the get-go. He started other chains, including Barbecoa, a pair of upscale steak and barbecue restaurants, in partnership with American chef Adam Perry Lang. At his peak, Oliver served 7.5 million meals a year and employed 4,500 people.

IT’S RARELY one thing that brings a big enterprise down, and Oliver was battling several dragons at once. Taxes and the cost of ingredients he favored went up. So did rent, especially in fast-gentrifying neighborhoods. But he kept expanding, sometimes into neighborhoods without enough traffic.

Casual dining had become a lucrative draw for investors, and the market flooded with competitors. People started using delivery apps instead of eating out. After Britain voted to leave the European Union in 2016, the value of the pound fell. Retail spending plummeted. Critics began to complain about his restaurants’ food and service.

Things were no longer looking so pukka.

“If you’re not bendy like this pasta, then you break,” he said as he rolled out sheets for the ravioli he was stuffing for lunch. “And that’s what happened.”

Friends wondered if he was spread too thin, or not paying enough attention. Others suggested he shouldn’t have hired his brother-in-law, Paul Hunt, a flamboyant former stock trader, as the chief executive. (Oliver said he needed to put someone he trusted in charge.)

Or, perhaps, he simply is not as good at business as he is at cooking and campaigning to help children eat healthier.

“Probably I was too trusting, which is one of my problems and also one of my benefits,” said Oliver, who estimated that he mishandles about 40% of his business ventures.

“There’s no way to sugarcoat it,” he said. “I thought I could fix it, but I couldn’t. I can absolutely look at myself in the mirror knowing I tried everything to the last very minute. We ran out of money. It’s as simple as that.”

Although he still has plenty of fans, there are, and always have been, detractors. They deride his accent as “mockney,” and hold him responsible for new school-lunch rules that banished foods like Turkey Twizzlers (essentially meat curly fries). They call him a hypocrite for his $6 million deal to sell healthy-ish Oliver-branded food at Shell gas stations despite his crusade against climate change.

When his empire collapsed, the tabloids were particularly brutal.

“There is something in the British psyche that sort of quite enjoys the discomfiture of successful people,” said food writer Nigella Lawson. “You get laughed at in this country for wanting the world to be a better place.”

It is hard, she said, for someone who attained so much fame so young to navigate the business world. “It’s nice to have some good things said about him, because he’s had such a hard time lately,” she said. “I have no doubt he will turn it around.”

IN MANY ways, Oliver is relieved to be out of the restaurant business. His empire is smaller now, with about 120 employees. He spends most of his day doing the things he loves: cooking, talking about cooking, producing content about cooking and trying to make the world a healthier place to eat.

Oliver’s other ventures still make plenty of money. He has sold a lifetime total of 27 million pieces of Tefal cookware, and it’s easy to find his kitchen gadgets on Amazon. He recently signed a deal to become the health ambassador for Tesco, Britain’s largest grocery chain.

Oliver’s preternatural ability to connect with an audience has helped him make the leap to digital content while other food media stars from his litter have struggled to fit content made for television onto platforms like YouTube.

He mostly stays off Twitter — “it’s not a platform that makes me a happier person” — but he crushes Instagram, where he has 7.3 million followers. His YouTube channel, Jamie Oliver’s Food Tube, has 4.4 million subscribers. His average monthly social media reach is more than 30 million followers, and his global TV audience is 67 million, said Saskia Wirth, head of communications for the Jamie Oliver Group.

Matt Duckor, vice president of video programming for Bon Appétit, said Oliver had a natural appeal that crossed generations.

“People 18 to 34 know who he is, and people over 50 know who he is,” Duckor said. “That’s very rare. In a way, there is this nostalgia play to it, but there is this sense that this guy is closer to the ground and closer to reality than a lot of his contemporaries.”

That’s one reason Bon Appétit focused on Oliver’s Insanity Burger in a segment of its new online series, “Reverse Engineering.” Chris Morocco, an editor with exceptional tasting skills, is blindfolded and must identify a dish only through taste, touch and smell, then try to recreate it. The 25-minute video featuring Oliver’s burger has been viewed 2.3 million times.

Books, however, remain the engine of the Oliver machine: He has sold more than 45 million of them — $7.4 million worth just last year, according to Nielsen Book Research — and is the country’s best-selling nonfiction author. For a time, only J.K. Rowling outsold him.

Oliver, who has dyslexia and what he says is an unusually short attention span, likes to dictate his books rather than type them. His topics swing with the times. He has veered from comfort foods to superfoods. He has produced 30-minute meals and 15-minute meals and five-ingredient meals. He has written recipes for squash mac and cheese for a family cookbook and, in 2018, interpreted dishes he learned from Italian nonnas.

His latest is “Veg: Easy & Delicious Meals for Everyone.” An edition for the American market (retitled “Ultimate Veg”) will come out in January.

He brushes off criticism that his books are derivative. “No one has a copyright on five ingredients or 30-minute meals,” he said.

He can be just as riled by people who accuse him of cultural appropriation for the way he adapts recipes. He has taken flak from Spaniards for putting chorizo in paella; from Jamaicans for spicing microwaveable, packaged rice with ginger and jalapeños and calling it Punchy Jerk Rice; and from West Africans for using parsley and a lemon wedge in jollof.

”I like parsley, and if I want to put it in my jollof, I will,” he said. “No one’s invented nothing unless they’ve invented sun and rain, and they ain’t.”

Dishes evolve, impacted by trade, war, famine and a hundred other forces, he said. “You’ve got the Brits getting passionate about fish and chips right now, then they get really upset when you say, ‘You know it’s a Portuguese Jewish dish in the first place,’” he said. “If you want to get back to really original British cooking, it’s thistle and cabbage.”

THROUGH ALL the turmoil, his marriage has stayed solid, he said. The couple plan to renew their vows on their 20th anniversary next June. Oliver still wears the necklace his wife gave him early in their relationship that reads, “I love you always,” and he writes her love notes on paper towels.

She is pushing for a sixth child, although he’s not so sure. Not that he doesn’t love being a father. He calls himself “an exceptional under-11-year-old dad” but perhaps only an “above average teenager dad.”

“Apparently, I’m a bit barky,” he said.

“I didn’t know how it felt to get achievement in education, but I knew how it felt to have tired feet and blistered hands from working,” he added. “So this means I am completely unprepared for two teenage girls that do care about learning and who do try at school.”

His oldest, Poppy, will be the first Oliver to attend college. “This,” he said, “is a big moment for us.”

And then there is the mission. Next to his family, doing his part to fix the food system matters to him the most. His list of campaigns, which he has waged with television shows and documentaries and all manner of political pressure, is long. Among them are improving school food, bettering conditions for chickens, reducing food waste, helping to pass a tax on sugary drinks and his latest, curtailing ads for fatty, sugary foods aimed at children.

His Ministry of Food, an eight-week community cooking course now in its 11th year, has trained nearly 100,000 people to prepare healthier food. His new North Star is the 2030 Project, an effort to coordinate health and governmental organizations in a campaign to halve childhood obesity by 2030, and it’s hard for him to stop talking about it.

That’s why the gaggle of government officials who shuffled by the test kitchen an hour earlier were still waiting for him to finish up lunch. He waved off his communications director, who had been gently trying to cut him off. He had a few last points to make.

“If I’m being reflective, I’ve had the best and the worst of it,” he said. “I’ve learned a lot. I smell differently now. I see differently now. It doesn’t mean I’m cynical. I still feel I have 20 years of good work ahead of me, but I don’t have an appetite to sort of see my name all over the globe in restaurants.”

He just wants people to be able to eat better, no matter what their economic situation is. And who better to take on such an impossible task?

“You don’t want someone who’s had success after success after success,” he said. “You want someone like me.”

© 2019 The New York Times Company