He laughs so much his entire body shakes. But it is no longer a body that wobbles, suggesting Chelsea's manager has given up something. 'Pasta, bread, sugar, oil,' he says.
'I have been given a diet by the dietician here at the training ground and I respect it. I was 100 kilos. Now I am 90. I feel much better.'
Score draw: Carlo Ancelotti loves tactics
The smoking, however, is proving harder to kick. In his sumptuous office in Cobham there is an unmistakable whiff of cigarettes and coffee, courtesy of his very own espresso machine.
'I started smoking when I was playing,' he says. 'I was 25, and at the time injured. I'd never smoked in my life but I tried a cigarette one day and I've been a smoker ever since.
'I do like it, to relax. After dinner. When I'm watching a movie. I know, when you see players smoking today, that it is not a good image. But until three years ago in Italy you could smoke on the bench. I used to like that, although I remember one time, when we were playing Ajax in the Champions League quarter-final in 2003. We scored in the last minute and Gennaro Gattuso jumps off the bench and grabs me from behind. I almost swallowed the thing.'
Ancelotti wants to talk about football. 'I love to discuss tactics,' he says before jumping to his feet and giving an impromptu lecture on the art of defending. He explains how Chelsea's approach is a mixture of zonal and man-to-man. He takes out his marker pen and starts drawing on the tactics board.
'You see?' he says. Kind of. But it is fascinating to listen to Ancelotti. This disarmingly modest man whose journey through football has been nothing short of remarkable. The players he has played with.
Fascinating: Ancelotti is disarmingly modest
The players he has managed. The success he has enjoyed. He has some interesting things to say about some of his managers. Fabio Capello, Sven Goran Eriksson. He says England's failure at the last World Cup was not the fault of Capello. He also talks, for the first time, about the recent death of his father. He is a wonderful raconteur. A guy whose stories are so rich in expression and detail.
He might sometimes wear that hangdog expression but this is a man positively bubbling with personality. Someone the players and staff must instantly warm to. Especially when he grabs a microphone, as he did on the open-top bus tour that celebrated last season's domestic double, and tries to sing.
Almost single-handedly, he has rebuilt an image of Chelsea that was tarnished by the chaos that often swirled around Jose Mourinho and the revolving door that was erected at the entrance to the manager's office. The Italian has made them likeable, and not just because of the football his team now play. Not just because they won the title last season by scoring 100 goals. Ancelotti has been a one-man charm offensive but it has been effortless in its execution.
Even Mourinho caved in when Ancelotti suggested they stop their very public verbal jousting and the two are now friends. 'If I can help to improve the image of this club, then good,' he says. 'I feel something special for this club. For me being a manager is never just a job. You have to show emotion. You have to give yourself to the club.'
He was giving to Chelsea - who face Wolves at home today - long before he even arrived at Stamford Bridge, it turns out. He gave them Gianfranco Zola, although not quite as an act of generosity.
Ancelotti blames his 'teacher'. 'I was a student of Arrigo Sacchi and he was very regimented in the way he organised his teams,' he says. 'At Milan it was always 4-4-2. Milan were a defensive team. Not an attacking team. We had great players but we used pressing to create attacking opportunities. Everything was very precise. When we defended and when we attacked. Even with players like Van Basten and Gullit, Sacchi expected them to fit to the system the way the rest of us did. He was obsessed with being very specific. Very organised.
'So when I started as a manager I was the same. 4-4-2. Even when it came to the team I had at Parma. I had a fantastic team. Buffon was the goalkeeper. Thuram and Cannavaro in defence. Crespo and Chiesa, Dino Baggio. We arrived in second place in 1997 behind Juventus.
'For six months I played Zola as awinger, because he had to fit into 4-4-2, and in the end he left, to goto Chelsea. And I lost a great player.'
In the same spell at Parma healso rejected the opportunity to sign Roberto Baggio. For much the samereason.
'Baggio wanted to leave Milan because he wasn't playing and hecame to speak to me,' recalls Ancelotti.
'So I asked him where hewanted to play, and he said behind the two strikers. I told him wedidn't play that shape, and told him he would have to compete withCrespo and Chiesa for one of the two striker places. I didn't wantsomeone in the hole. So he said no, and joined Bologna.
'If the same thing happened now, 14 years later, I would buy him."Come!" I would say, "and we will work it out". I lost a great abilityto improve the team with the ability of Baggio. But that was a lack ofexperience. I had been a coach just two years. And, as I said, myteacher had been Sacchi. I didn't have the knowledge to know I couldchange things. And maybe I was a little bit scared to change because itwas the start of my career.'
He changed when he moved to Juventus and encountered a certain Zinedine Zidane.
Never lose it: Ancelotti kicks a ball during a training session
'I realised you can't play Zidane as a central midfielder or a winger,' he says. 'So I played with three defenders, four midfielders, Zidane and two strikers.
'In Milan, also different. It is important to have good organisation, play quickly, have the right movement. But I knew by then that you have to build the shape of the team to the characteristics of the players.
'It is very important to use good organisation but also use the instinct and ability of the players when you attack. It's different when you defend. When you don't have the ball players have to take up the right position.
'But with attacking it is different. Here at Chelsea I have to use the ability of someone like Nicolas Anelka. You don't lock him inside a system. To show his qualities he needs to move. 'It is the same with Didier Drogba and Florent Malouda. But when we lose the ball I ask all of them to work for the team.
'At Milan I had attacking players. Pirlo, Seedorf, Rivaldo, Kaka, Rui Costa. I tried to put them in a good organisation. Seedorf wanted to play behind the striker but I made him a left-sided midfielder, in the same role Frank Lampard plays for us here.
'Gattuso wanted to play holding midfielder, but I played him on the right like Michael Essien. A lot of players didn't play in their preferred position but to be a top team you have to fit into the right structure. Kaka still had to work. Not strong work. But he has to take up the right position and be in the right position for when we win back the ball.' Only Ronaldo, at his fattest, escaped such duties. 'But even at 100 kilos you could just give him the ball and he would score,' he says.
Ancelotti delights in talking about players. He talks about Zidane and how 'he would spread butter on the ball' in the way he controlled it.
'Spalmare,' he says, pretending to pass a knife across a slice of bread. But he loves his strikers. 'All strikers have different capabilities,' he says. 'But Inzaghi is the best striker in the box I have ever seen. As a predator. He has a smell. More than 70 per cent of his goals were with one touch. Which means he is arriving in the right position.
'Crespo was fantastic without the ball. His movement. While Drogba is more like Shevchenko and Del Piero. I have been lucky with the strikers I have had. All very good.'
This interview took place before Ancelotti made what appeared to be slightly mischievous remarks about one day managing England. But he is a huge admirer of English players, dismissing the idea that failure at international level is down to a lack of technical ability compared with players from other countries.
'That's not true,' he says. 'Absolutely not. Technically they are fantastic. Tactically too. And their character. Their professionalism.
'Gattuso was a great professional for me, but it is rare to find players like him in Italy.
'Here, I don't know if I am lucky but Ashley Cole, Lampard, John Terry, as professionals on the training pitch, in matches, they are fantastic. When they are on the pitch. 100 per cent. Always. And sometimes that can be a risk. Sometimes you need to take a rest. Back off. But they never do. They are very professional.
'Brazilian players, for example, are totally different. They like to joke around in training. It can be difficult to maintain their focus. For me there is a time to be serious and a time to joke.
Enlarge The rise and rise of Carletto
'The problem for the national team is not tactical. It is not Capello.
'I was surprised by the World Cup, because, really, the England team have top players. Ashley Cole, Terry, Ferdinand, Gerrard, Lampard, Rooney. They are top players. It was a strange World Cup. I don't know the reason. But, as I said, the problem was not tactics because I know Capello.
'I have never managed an international team but one of the most important things has to be personality and courage, because you don't have time to build a shape the way you can at a club. Physically you have to be good. I think during the World Cup a lot of the England players were not 100 per cent. Rooney for instance.'
It seems he would not blame Eriksson either. The Swede coached him at Roma and he says: 'I liked Eriksson. He was very young when he came to coach us. I think 38. But tactically he was very good. A lot of new ideas. And he had great knowledge of football.'
As does Ancelotti. He is a real student of the game, and someone who will happily share his methods. 'When I was learning to be a coach I would ask to go and watch training sessions and some managers would say no,' he says.
'But with me there are no secrets. Anyone can come. I would like the journalists to come sometimes, so they can understand better what we are doing.
Just champion: Ancelotti after winning the Premier League last season
'I was lucky. I had a great education. Sacchi, Eriksson, Capello. But even since then the game has changed so much.
'The speed of the play. When I played and a team-mate passed to me, I had the time to control the ball, look, make a decision and pass the ball.
'Now you have to make that decision before the ball has arrived at your feet. Otherwise it is too late because players are fitter and faster and tactically teams have improved.
'The pressure on the ball is so much greater now. If you are able to cope with this, the play is quicker. To play quick, efficient attacking football is what we try to do here. The speed of the play is the most important thing.'
Only when it comes to the 'Milan Lab' techniques that he has now transferred to Cobham is he said to be more secretive. 'No,' he says. 'It was something I started when I arrived at Milan. There were a number of players over 30 years old and we had to take care of them; prevent them from suffering injuries.
'It was a case of dealing with players as individuals and monitoring them. Physical tests, psychological tests. Compiling the data. That way you can control the recovery of a player. You know if they are under stress, tired. If they don't sleep well. Physical data.
'We now have something similar here. It is all about the recovery of the player. Games and training can destroy the muscles and you have to load the training accordingly. We use GPS. Measure heart-rate. I brought Bruno Demichelis over from Milan to do all this.'
There is a never a right time to mention such things but there is one figure in his life he has not yet discussed. His father Giuseppe, who passed away last month.
'My father died,' he says. 'He was 87 and for 86 years he had a fantastic life. The last year was not so good. I tried to stay close to him.'
'Was he your greatest inspiration?' I ask. 'Always,' he says, his voice breaking with emotion. 'He was a good father.'
Having met his son, that much is obvious.
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Explore more:People: John Terry, Michael Essien, Fabio Capello, Frank Lampard, Sven Goran Eriksson, Jose Mourinho, Gianfranco Zola, Ashley Cole, Didier Drogba, Zinedine Zidane, Nicolas Anelka, Carlo Ancelotti Places: Milan, Italy, United Kingdom