A report in Sport in July claimed Hazard was seven kilograms too heavy when he joined up with the Madrid squad for pre-season duty.
The Belgium star has found it difficult to kick-start his career in LaLiga since joining from Chelsea in the transfer window, only scoring his first goal for the club in last weekend's 4-2 defeat of Granada.
Martinez, though, does not believe Hazard's physical condition is a particular concern given the talent he has.
"He is a really calm person, not someone who looks for individual glory," he told Deportes Cuatro."Whether he's carrying weight or not, Hazard can break past and unsettle defences and make a difference.
"His innate talent doesn't depend on whether his weight is this or that."
Martinez also spoke in defence of goalkeeper Thibaut Courtois.
The 27-year-old was taken off at half-time of the 2-2 Champions League draw with Club Brugge with what Madrid described as a stomach problem.
The club was forced to deny Courtois had become ill due to anxiety, having conceded twice to Brugge in the first half to compound a difficult run of form at club level.
Martinez says Courtois is still recovering from illness and insists he is the world's best in his position.
"It wasn't true that he had anxiety," Martinez said."He is still feeling the effects of a stomach bug and needs to regain a kilogram or two. That's what can happen with a stomach bug.
"He is a player who dreamed of playing for Real Madrid from a young age and he is ready to define an era there. I am convinced that he is the best goalkeeper in the world."