The 56-year-old Masterchef presenter said that the shutdown has led to him being able to control his diet for the first time in nearly two decades.
The TV host said having a period where he did not film any cookery programmes meant he could focus on eating healthily rather than consuming what producers told him to.
Gregg has shared his new health and fitness routine on social media with regular updates for his 107,000 followers on how it has been progressing.
Speaking about the lockdown earlier this year, Gregg said it “has been brilliant for me”.
He continued: “Lockdown was the first time ever in nearly 20 years that I had complete and utter control over everything that I ate. It was amazing.
“Because normally… you can walk in on MasterChef and the directors go, ‘Right, we’ve got a pudding challenge today’.
“And you go, But there’s eight of them?”‘
Gregg continued: “And if you’re on the road, you’re eating whatever the hotel has or whatever the location caterers [make].
“But to be at home eating whatever I wanted was brilliant.”
With Gregg in his fifties, he said that he “didn’t look like that when I was 26” before adding: “It’s quite phenomenal, isn’t it?”
He said that the “secret” to his weight loss is “lots of lean protein” and “loads and loads of veg”.
Gregg added that he has “never been really strict” and “you don’t want to live life as a nun”.
He continued: “You want to be able to drink beer, drink wine and it’s not about starting something with evangelical zeal, it’s about picking up healthier habits.
“What I’ve realised is, the healthier and healthier your food choices become, eventually they’re habits your body and mind has picked up and that’s then what your body starts craving.
“So, it no longer craves a chocolate doughnut, what it craves is a ripe pear.”
Gregg returns to television screens next week for MasterChef: The Professionals.
He said filming “wasn’t weird, it was just different” despite the coronavirus measures which were in place.
“What was different was that there was no social mixing of the crew who have known each other for over 15 years,” he said.
“That was what was odd. The only real change to the MasterChef filming was that me, Marcus [Wareing] and Monica [Galetti] used to huddle around the plate, elbowing each other out of the way for the choicest bit and now, obviously, the chef brings the dish up and we take our own bits off there with clean cutlery.
“It’s probably a little bit more sophisticated doing it this way. No tussling for the chicken wing.”
*MasterChef: The Professionals starts on November 10 at 9pm on BBC One.
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