Ed Gamble is looking at the menu and I’m panicking. Panicking, because I want his approval: I chose the restaurant. Panicking because I can’t decide what to eat, even though I planned in advance. And panicking that I’m going to choose something he wants, because he has just told me that if I do, he will change his order even if it means eating something he does not like. “I hate it when everyone orders the same thing. I’d rather punish myself, just to prove a point.”

The reason I feel under pressure is that the 38-year-old comedian has become one of the most influential people in British food. It is a feat beyond his wildest teenage dreams: he is a judge on BBC One’s long-running chef competition Great British Menu; he has written a memoir, Glutton, with the subheading “The Multi-Course Life of a Very Greedy Boy”; and most importantly he is co-host of the Off Menu podcast, which recently completed a sold-out tour of the UK and on which for the past five-and-a-half years he and James Acaster have invited 239 famous guests (from star musicians to A-list actors to their comedian friends) to their Dream Restaurant to tell them their favourite ever starter, main course, dessert, side dish and drink (not in that order). 

Dinners at the Dream Restaurant are long and surreal and indulgent and boisterous and very, very silly. Listen to the joyous Bob Mortimer choosing a “lovely bit of tongue”; Claudia Winkleman revealing she refuses to drink water; Steve Coogan’s tantrum about the decline of white pepper, Paul Rudd talking about how repugnant he finds mayonnaise. Gamble and Acaster involve you in their in-jokes, they transport you to the smalltown curry houses from their guests’ childhoods, they convert even their least foodie listeners into restaurant nerds with long lists of dishes they want to try from around the world. A mention on Off Menu can be transformative for a restaurant or food brand; for their lesser-known comic guests, an appearance on it can – like Taskmaster, or Live at the Apollo in decades gone by – turbo-charge a career.

They didn’t plan for that. At the start, Gamble says, “we just went, ‘we love food – we’ll have a chat about it’”. But Off Menu has also become one of the most positive and life-affirming places to talk about food, without snobbery or judgement, without engaging with diet culture or trying to make statements about contentious issues in the food world (though Gamble’s keen to stress it does not avoid them). Mainly it’s a place for very big opinions about things like cheese boards. And notably, unlike, say, Desert Island Discs, on which so many interview podcasts are modelled, it is not a medium for guests to talk intimately about their lives or expose their souls. 

No, Gamble and Acaster really do just want to know if you’re picking poppadoms or bread, or still or sparkling water. (Today, Gamble is drinking the hard London tap water he grew up with, which I know from listening to every episode of Off Menu, he will always defend over the soft stuff almost all of his northern guests prefer. Which also makes his hair go fluffy.)

The very tall and very tattooed Gamble and I are in Nessa, a new-ish restaurant in Soho where (fortunately) we decide to order several small plates to share. “I don’t want to overdo it today,” he says. “Normally, after lunch I just kind of curl up like a python.” Woodfired leeks, tomato panzanella, smoked salmon crudo, cheese and onion croquettes, “pork and sage stuffing, brioche – those are words I like”.

You would not know it from sitting next to him as he commands the table, from the way he scours food blogs, from the detail in which he tells me about his favourite recent meals (L’Enclume in Cumbria for a birthday; Speedboat Bar in Soho three times in a week), or his childlike excitement when the food arrives (the leeks are his favourite), but Gamble was not always geeky about food. Until he was 23, he just ate a lot of it.

Gamble grew up in Wimbledon, south-west London. His mother, a nurse, and father, a solicitor, divorced when he was four – he lived with his mum most of the time, and was very happy. He was an only child until he was about eight, when his father had two more children and from a very young age, he had a discerning palate: in Glutton, he remembers his appetite for olives and poached salmon, rejecting the kids’ menus and requesting what the adults ate, attaching himself to “feeder parents” at his friends’ houses who were impressed by his willingness to eat proper food, and so gave him more and more of it. By the time he went to secondary school, it dawned on him that his weight was not something society celebrated. So he decided to make “chub” part of his brand. “I was the funny fat friend, the funny fat fresher,” he says.

The degree to which Gamble stresses that his is not a sob story, when describing his experiences as an overweight child or his type 1 diabetes diagnosis at age 13, is one of the great strengths of his book. “I think it’s an important thing to tell people,” Gamble says. “When I was bigger, I wouldn’t have liked to read a book about somebody who lost weight going, ‘I was so sad back then. And now I’m finally the person I always wanted to be,’ because that’s really horrible to hear. And it also just wasn’t true. At all. I had a great time.” That makes it a delight to read. His night of four pizzas, when he was a philosophy student at Durham University, is not a nadir, but a climax.

Gamble was not miserable. He did not have a traumatic time at school. “I think I was pretty good at owning it when I was a big guy,” he says. It wasn’t the sole reason he became a class clown – there was the time when he was 11, playing a super camp French woman in a production of Oh! What a Lovely War, singing a rude song, getting a massive laugh, when he knew he needed that feeling again – but he doesn’t think it was insignificant, either.

“There are definitely a lot of clichés about bigger people developing comedy as a defence, and being unpopular at school,” he says. “And that wasn’t totally my experience. But – I hate it when clichés are true – there are some truths as well: I was funny anyway, but I almost certainly tried to be funnier to make that my thing in school, rather than being big.”

But in his early twenties, when he was starting to get attention as a gigging comedian, he grew defeated by what was, he writes, “my own desperation to be seen as attractive”. So he started eating “normally”, and he simply lost weight. Eventually, he got into running, and realised he loved exercising. He ended up running the London Marathon. He became exactly the person he’d spent years mocking. That was strange. He felt like he’d let down the person who was proud to be big. 

“I had a lot of friends who are bigger as well. And you sort of feel like you’re breaking away from the gang a little bit… You spend your whole time slightly off to the side going, ‘What are they doing? They’re wasting their lives.’ And then you do it and you’re like, ‘Oh, there is a reason people enjoy it.’” It also marked a shift in how he saw himself, and how others saw him. “That used to be my identity. And now I don’t have that as my identity.” He jokes: “I had to pivot to diabetes, just to have a brand.”

When Gamble lost weight, he also became a rule follower. He was never much of one before. At King’s College School, “I was one of the naughtiest boys, probably”; at Durham, where he joined the sketch group the Durham Revue and became inseparable from Nish Kumar and Tom Neenan, with whom he is still close friends, “I was not doing the work and just wanted to chat comedy”. But Gamble has an obsessive personality, he says, and when “I found I had willpower, I saw that following some rules actually had some effect”.

Running, losing weight, his appearance, food, which he was now enjoying much more, all became obsessions. “I started to go, ‘Is this right? Am I doing this right?’ And that sort of gets into your head and you start overthinking. And I still have that to an extent, these days, but I found balance with it.”

If you listen to Gamble’s podcasts – as well as Off Menu he presented The Traitors: Uncloaked, Taskmaster the Podcast and has a programme with comedian Matthew Crosby on Radio X – he seems sensible, dry, the straight man – especially opposite the freewheeling deliriousness of Acaster. That’s related to that willpower, he thinks.

“Historically, through British comedy there is that sort of fusty person who wants to stick to the rules – they’re a well-worn trope.” Despite his childhood mischief, “I think that’s my natural personality. I am just terrified of being told off all the time. I quite like having to be the controller sometimes – I like to make sure we’re doing everything right. If there were two James Acasters on the podcast it would be unlistenable.”

I also get the impression that rule-following makes him quite controlled about what he reveals of himself, but he corrects me, sort of. “You say I didn’t mine the depths of my psyche in this book, I think I probably did, I just don’t have a very deep psyche.” On stage, rather than the searing or savage or personal or simply weird shows of many of his peers, he is not attempting anything other than making people laugh every 10 seconds, “otherwise I panic”.

There, he is the storyteller. “I think comedians connect with our past more than a lot of other people, because we’re constantly looking for stories we haven’t told people yet”. In his shows – he is on tour now with a show titled Hot Diggity Dog – he riffs on his immaturity, on being middle-class, on his lack of edge (notwithstanding a love of heavy metal), occasionally on life with his wife Charlie Jamison, a TV producer. And diabetes.

“I’m from a generation of comedy where there are many privately educated white straight men like me, so it’s lovely to have an angle,” he says. “Posh white straight man is a category in comedy, whereas it used to be the dominant. That’s a good thing. I just need to make sure I’m the best posh straight white man.”

‘Hot Diggity Dog’ is touring now (edgamble.co.uk); new episodes of ‘Off Menu’ are released every Wednesday; ‘Glutton’ is out now in hardback (Transworld, £20) and is published in paperback on 23 May