He also fears he has "a steep hill to climb" to stop Red Bull's Max Verstappen from dominating Formula One.
Hamilton finished second for the third time this year when Verstappen denied him victory with just six laps remaining of a thrilling United States Grand Prix.
Moments after stepping out of his Mercedes, the seven-time world champion said his narrow defeat to Verstappen filled him with hope that he will be a winner again.
But Hamilton also conceded that the race at the Circuit of the Americas was probably his best shot of taking to the top step of the podium this year, with only rounds in Mexico, Brazil and Abu Dhabi remaining.
"We need to be realistic," the 37-year-old said. "The Red Bull car has been the fastest by far all year.
"It was great to have started third, and been in a position to fight for the win, but on true pace, they have been ahead of us all weekend. They were (on Sunday), and they will be at the next three races.
"Unless something drastic happens to them, then it's highly unlikely that we will have the true pace to be able to compete with them. This was probably one of our best chances of winning. But we will give it everything we've got."
Despite a poor pit-stop dropping him to third, Verstappen moved past Ferrari's Charles Leclerc and Hamilton to take the chequered flag and tie Michael Schumacher and Sebastian Vettel's record of 13 wins in a season.
It was also the 33rd victory of his career, moving him ahead of Fernando Alonso and into sixth on the all-time list, with only Hamilton (103), Schumacher (91), Vettel (53), Alain Prost (51) and Ayrton Senna (41) ahead of him.
Verstappen's Red Bull team will also head to Mexico City this weekend undefeated in their last eight outings. On Sunday, they secured their first constructors' championship since 2013.
Asked if F1 is set for an era of Verstappen rule, Hamilton said: "It is too early to say, but if we get into next year and they're dominating again, then yes.
"The Ferraris have been quicker than Red Bull throughout qualifying. Now, all they need to do is pick up their race pace, and they'll be right with them.
"We're working on making a car that can fight, but we've got a much, much bigger step and steeper hill to climb. Hopefully it will not be impossible."