Force India have asked their drivers to lose weight before Melbourne.

Up and down the pitlane, drivers have put on as much as 5-6 kilograms of muscle over the winter to prepare for the new cars' much higher G-forces.

Yet Force India are struggling with handling problems, and Germany's Auto Motor und Sport said that one problem is that the team's 2017 car is overweight.

"We told them they should weigh 70 kilograms in Melbourne," said technical boss Andrew Green, referring to Sergio Perez and Esteban Ocon who both apparently weigh 72kg.

Deputy team boss Bob Fernley said the main problem is that the task of adjusting to vastly different regulations is harder for smaller teams like Force India.

"We're currently fighting for fifth place with Toro Rosso, Haas and Renault," he said. "Williams is too fast for us, but we're catching up. The season is long."

The Australian Grand Prix takes place on March 26.