"It was the combination of the stress of lockdown [and] I think a change in my medicine," he said.
"I did get a better diet with a muscle food company that was supplying me with protein.
"I think the major thing was that I had to look after my son while my wife was being a nurse on the front line. And looking after him 24/7 almost killed me.
"By the end of the day, I was exhausted. I think that was one of the reasons I would collapse into a heap rather than grabbing a snack at 7 or 8pm."
In March the quiz show star spoke to the Sun about his weight loss and said he felt the "lightest" he had been in 25 years.
"My knees really feel the difference. I will never be athletic again but I just move so much better for not carrying that extra weight."
Labbett said there was no surgery or quick fix behind his health overhaul, just some fundamental changes to his diet and exercise regime.
"Sugar has always been my sin, and it's why I never contemplated a gastric band," Labbett told the Sun.
"The more sugar you have, the more you want. Now I've reduced it, I'm just not that hungry any more.
"I always try to have a decent breakfast, a cooked breakfast, because it's actually quite good for you, and maybe just a muffin or two for lunch if I'm filming.
"I'm often just too exhausted in the evening to eat, and just go to bed without. It works for me."
