Toro Rosso's Jean-Eric Vergne says he even visited hospital after the Australian grand prix.
"I did a diet this winter but you get to certain limits that the body can no longer take," he said, clearly urging for an increase in the weight limit.
But Todt, the president of the FIA, said it is up to the drivers to manage their weight loss in a healthy way within the existing rules.
"Honestly, I don't know why a driver ... I think normally you can do a good diet and not have to go to hospital because you have been losing some kilos," he is quoted by the Telegraph.