For the past 10 years, Jamie Oliver has campaigned tirelessly to reform school dinners in the UK and ban turkey twizzlers for good.
But in the background, the celebrity chef has also given his own diet a complete overhaul.
In the run-up to his 40th birthday, Oliver has lost around two stone in the space of three and a half months.
The key to his body transformation? Sleep and seaweed, apparently.
Jamie Oliver left in 2010 and right in March 2015
Oilver has gradually slimmed down since her became a household name 16 years ago with BBC show The Naked Chef, but this year he's made a conscious effort to improve his health.
According to an interview in The Sunday Times magazine, Oliver had a "bit of a freak-out" 15 months ago when he realised he wasn't as young as he used to be.
"When you come to 40, you think you’ve got a while, but it’s ticking," he said.
"You start to realise that you’re half dead, so let’s get on with it. I want to get as old as possible, and to do that you’ve got to live a certain way. That’s the rules of the game."
He studied nutrition and consulted sleep experts to lose the two stone.
In another interview, Oliver went into detail about ditching comfort foods and adding new ingredients to his repertoire, such as seaweed.
"I thought seaweed was hippy, globetrotting stuff but our ancestors ate seaweed. It’s got a load of iodine and it’s the most nutritious vegetable in the world. I’m saying lose it in a minestrone because that stuff is really, really good for you. It’s like dynamite – fibre, nutrients, all the minerals, aids digestion – unbelievable," he said, according to the MailOnline.
Jamie Oliver at Food Revolution Day 2015
He's also recommended eating a handful of nuts per day, using home-grown herbs for seasoning and switching meat for eggs on occasion to keep your body healthy.
On top of that, he's trying to be more mindful about the amount of alcohol he's drinking each week.
As well as shaking up his diet, Oliver has revolutionised his sleeping habits.
The chef previously admitted to surviving on just three and a half hours of sleep per night, but these days he's getting plenty of shut-eye.
"Sleep has become profoundly important to me,’ he said.
"I was never getting enough of it and I didn’t understand the value of it. And I treat it like work. Just like I do with little Buddy [his four-year-old son] when I tell him to get to bed, I get to bed. I have little vibrating things that shake me when it’s 10pm."