Nutritionist Giuliano Poser has confirmed that he helped Lionel Messi change his diet, leading to the Barcelona star's outstanding 2014-15 campaign.
Messi scored 58 goals and contributed 23 assists as Barcelona won the Champions League, Copa del Rey and La Liga Treble, making him a huge favourite for the 2015 Ballon d'Or award.
This followed a disappointing 2013-14, which was disrupted by injury and saw Barca fail to win a trophy for the first time in six seasons.
Messi then started the World Cup impressively but appeared to tire and was unable to prevent Argentina from losing 1-0 to Germany in the final.
A number of reports put his upturn in form down to a new diet, with Blaugrana transfer advisor Charly Rexach revealing that Messi had "eaten too many pizzas" in the past.
The player was photographed meeting Poser in Italy during a break from action in April.
In an interview with Gazzetta dello Sport, picked up in AS, Poser, from Argentina, said Messi had taken a tip from his international colleague Martin Demichelis and consulted him.
"I am a good friend of Demichelis and he recommended he [Messi] visit me," Poser said. "After the World Cup, something changed. Messi had the intuition and humility to try and do something different in his professional life."
The 59-year-old kinesiologist, whose methods reportedly include the use of Bach flower remedies, emotional therapy and a balanced diet, said the change from processed to natural foods had allowed Messi to train with greater intensity.
"He eliminated processed foods and replaced them with foods rich in vitamins -- cereals, vegetables, fish and olive oil," Poser explained.
"He had won everything, but wanted to continue this excellence for years and understood he had to change something. We are talking about a very intelligent and intuitive person."
Demichelis' Manchester City teammate Sergio Aguero is among other top players to have visited Poser at his base in the small Italian town of Sacile.