When Arsène Wenger arrived in England in 1996 he was alarmed at the diet – or more accurately, lack of diet – among his Arsenal players. Wenger banned chocolate immediately, causing senior members of the squad to bristle with resentment. He recalls the resistance en route to his first game: “We were travelling to Blackburn and the players were at the back of the bus chanting: ‘We want our Mars bars!’” Almost 25 years later, the landscape has changed dramatically in English football. Clubs now provide detailed nutritional advice to their players, with the richest clubs even employing full-time nutritionists.

Shortly after Jürgen Klopp moved to Liverpool in 2016, Mona Nemmer joined the club as head of nutrition from Bayern Munich, where she had worked with Pep Guardiola for three years. She quickly established individual dietary plans for every player in the first-team squad. Her sphere of influence does not stop at the club’s training ground, but extends to what players consume on the team bus, in the hotels they use for away games and even their homes. “Some players like to cook for themselves, some like to take away a packed bag with food in, but here we like to react individually,” she says. “If the player wants a cooking lesson, or their wives or girlfriends do, we are free in the sense to help them with whatever they need.” A Liverpool FC recipe book was even mooted but it has yet to see the light of day.

Some players go to the extent of hiring their own personal chefs. Harry Kane started working with his own chef a few years ago. “It kind of clicked in my head that a football career is so short. It goes so quickly, you have to make every day count,” he said in 2017. “I have a chef at home to eat the right food, helping recovery. You can’t train as hard as you’d like when you have so many games, so you have to make the little gains elsewhere, like with food. He’s there every day, Monday to Saturday, and leaves it in the fridge for Sunday. I hardly ever see him because I’m at training, but he’ll cook the food and leave it in the fridge. We’ve got a good plan going.”

Kevin de Bruyne, Ilkay Gündogan, Luke Shaw, Paul Pogba and Phil Jones are among the Manchester-based players who use the services of Jonny Marsh, a private chef who was trained by Raymond Blanc before working for billionaires and on private yachts. Marsh started working in football when Manchester City contacted him to ask whether he would make Christmas dinner for De Bruyne.

De Bruyne is particularly fond of carbonara, so Marsh spent a few months developing a recipe for the dish that tastes right but has none of the usual ingredients. “The players love simple food. Kevin De Bruyne’s favourite dish is the ‘Kevin Carbonara’ - which is not bad for you at all,” writes Marsh in his food column for the Mirror. “The attention to detail that goes into something that looks so simple is huge. Making sure I’m using natural anti-inflammatory and recovery agents from food on specific days enables players to recover quicker, making sure that players with certain deficiencies are able to eat normal food without having to ram certain foods down them. I make sure that snacks, desserts and breakfasts, fuel, recover and aid them in their days.

“The way it works is, I ask what they want that week and then me and my chefs will start prep on a Monday and get everything ready for everyone. Then we deliver all over the country to players. It’s mad though – word gets out if someone’s playing well and suddenly everyone wants to eat what they had.”

Marsh liaises closely with club nutritionists, such as Tom Parry at Manchester City, to ensure menus are specifically tailored towards the players’ requirements. Nutritional advice will differ depending on the players’ age, metabolism, position and even taste, says Dr Mayur Ranchordas, a nutrition consultant who currently works with Wolverhampton Wanderers. “We are dealing with a variety of different cultures and different tastes. So we create diverse menus suitable for a Mediterranean diet, as well as English or South American ones. You have to make allowances for that.” Wolves employ several chefs to cater for the individual tastes in their squad.

Ranchordas has worked in football for decades and has noticed how attitudes have changed over time. “Nutritional support was brought in as and when it was needed, rather than being a service that is required on a day-to-day basis,” Ranchordas says. “Nuno [Espirito Santo] is very open to anything we can do to help players from both a performance and recovery perspective. It has become more holistic. Ten years ago players would pay attention to what you were saying, but they weren’t that fussed about applying the info. Whereas now players are so much more receptive and open-minded as they realise what impact good nutrition can have on their performance, recovery and injury prevention and will act upon it accordingly.”

Facebook Twitter Pinterest Arsene Wenger in 1999. Photograph: Jamie McDonald/Getty Images

The technology available to nutritionists has also improved, with everything from heart rate and body fat percentages checked and monitored at all times. “I have continuous feedback and data,” Ranchordas says. “For example, when we do the bloods, we know if players are deficient in certain nutrients. So, some players might need vitamin D or Omega 3, or they might be lacking iron, so you can target the nutrition intervention through adapting their diet and providing supplements.”

What players eat also depends on their position on the pitch. The players who cover a lot of distance – such as full-backs or box-to-box midfielders – expend more energy than centre-backs or goalkeepers so will need a lot more calories. Chris Rosimus, who has worked with Leicester City as well as the England cricket teams, says: “For a footballer there’s a huge emphasis on ensuring that the body is loaded with fuel before a match, mainly through carbohydrates so that they can perform and delay fatigue over those 90 minutes,” Rosimus says. “Whereas cricketers can be in the field for a long period of time for many days in hot conditions so it’s not highly anaerobic work. Although they might need comparable amounts of calories, the distribution of the carbohydrates, fats and proteins would be entirely different.”

Facebook Twitter Pinterest Chris Rosimus has provided nutrition advice for Leicester City and the England cricket teams. Photograph: Matthew Lewis/Getty Images

“Most players will eat five times a day,” Ranchordas says. “They’ll have breakfast then train, followed by lunch, then after more training they will have a mid-afternoon snack followed by dinner and lastly a protein meal or shake with a bit of fruit before they go to bed. With nutrition what you eat before, during and after can have huge implications on how you perform and on how you feel.

“If you think about how many meals a football player eats in a typical season, how many games they play, small changes in what and when they eat plus the quality of that food has massive implications on how they feel and how quickly they can recover so that is why nutrition is no longer overlooked or viewed just as a treatment but very much as a performance enhancer.”

The days of the whole team eating the same meals together are long gone. “When I first came into the industry there was pretty much a blanket approach,” says Rosimus. “But nowadays, although the food provision is roughly the same, how that is applied to individuals is very specific. So chicken and pasta will always be staples of a high-performance diet but how and when they are consumed is what makes it different.”

Aside from providing guidance and healthy menus, nutritionists occasionally have to warn players off particular foods, as Ranchordas recalls. “A few years ago a player came to me as he had been told by some of his fellow professionals that eating bulls’ testicles would increase his testosterone and he wanted to explore that. That’s probably the weirdest thing I have had to deal with during my time in the game.” One imagines there were not too many protests when this particular foodstuff was taken off the menu.

Richard Foster’s new book Premier League Nuggets is out now and you can follow him on Twitter.