Gasperini will want his players in early with the European Super Cup against Real Madrid to be played in August.
On his message for the players, the coach said: "Don't be fat!
"Everyone can play football, except those who are fat. They won't have time (to put on weight) with the Euros and other things. We'll start again on July 10. Those who will play with the national team will get 20 more days, which will be more than deserved. Players will arrive at different times, we'll have to adapt, but we are ready. There will be a desire to start again."
He also said: "Everything can be improved, even Madrid can improve if they add Mbapp.
"The key thing is to make players fit together. We want to improve the team. Opponents will pay even more attention to us so we must improve."