Three years later and the Salisbury-born Kerridge has lost over 10st thanks to his newly-created Dopamine Diet.
"I think a lot of people when they get to forty have a reflection on yourself, you start to think about where you've gone, what you've done, what you've achieved and where you are going in the future," Kerridge explains in his distinctive Gloucestershire burr.
"So it was a reflection of where I was at, and I had to think about how I would make it work, how I would stick to something that was long-term.
"Many people can do it 4-6 weeks and drop a dress size, but I wasn't looking at that, I needed to do something bigger than that," he adds.
"So I had to look at diet methodology and ways to do it in a way I could stick at. And I thought choosing lowcarb was the way for me."
And Kerridge – who has made his name as a passionate advocate of traditional Great British food in all its many forms – is proud that his Dopamine Diet is not just a new cookbook or a fleeting eating fad, but rather a "personal story."
"The biggest problem you have if you're my age and overweight, is that you have nothing in common with everybody else in the gym, or so you think," he says.
"You've got this super-fit guy or girl telling you to eat skinny or to do this or that and they're stood there with their six-pack and their training gear.
"They are so far removed from where you are, you just feel so far away from that state. And it's a really difficult place to jump into, especially if you have low confidence, and so you give up before you even start.
"With my book, I've already been there, I've already done it, it's how I did it and little tips on how I did it myself," he continues.
"It"s the difference between being told not to do it and being shown how not to do it by someone who has already lost 11st and has done it the right way – the way that worked for me, at least.
"It"s something that I hope is inspiring and helpful. If just one person buys into it then it"s been worth doing, the book, because it means that it has helped that one person change their life."
Having gone completely tee-total alongside cutting out the majority of carbs, Kerridge says the most important bit of attempting to lose weight is to just jump straight in.
"So many people say "I'm going to give this a go" – but that's the wrong attitude,"he says.
"What you have to say is "I'm going to do this." If you say "I'm going to give it a go" you are only giving yourself an excuse to say "Nah, it didn't work"; you need to just step into it and say you are going to do it, and mentally I think that"s the hardest part."
Tom Kerridge"s Dopamine Diet is available now from Absolute Press. RRP £8.99.