A lizard can live without food varies from species to species. Adult bearded dragons can survive for up to three weeks without eating, while adult leopard geckos can live for over a month without eating. It also depends on whether the lizard is an adult or a baby.
Crested geckos don't live as long as leopard geckos if there is no food source. However, most lizards can store water and fat in their tails which can help them to survive. Mostly, the length of time a lizard can survive without food depends on whether or not the species of lizard eats for storage or nourishment.