That's essentially what's happening at Renault F1 this season with their rookie Vitaly Petrov. The Russian driver is almost as tall as his team-mate Robert Kubica, but crucially weighs some 10 kilograms (or 22 lbs) more. Kubica made headlines in the last few years at BMW-Sauber, where he went on an extreme weight-loss regimen in order to improve his performance.
Petrov, meanwhile, just managed to finish his first grand prix and score his first championship points this past weekend in Shanghai, having failed to make it to the finish line in the three previous rounds.
According to reports, the French team has instructed its driver to lose a few pounds. Trimming weight off the driver's body mass allows the engineers to play around with extra ballast (required to reach the minimum curb weight allowed under regulations) and trim the car's handling accordingly.