There are differing ideas on this, depending on who you talk to, what their experience has been,a nd what their agendas/goals happen to be.
Some people will say chameleons do not, or cannot overeat - especially babies.
Ignoring chameleons, for the sake of neutrality, we can look at other herps.
In all other reptiles, captivity affords them conditions they will not see in the wild. Int he wild, they must hunt, and they are dealing with a parasite burden on their bodies as well. Furthermore, food is not always present - they don't get feeding oppurtunities as mucha s captive animals - no matterhow much food is present in the wild, it's not like in captivity. Plus, you have unnaturally high nutrient DENSITY. 10 random wild bugs, hard shelled beetles and grasshoppers, are not going to contain as much protein, fat and overall calories as 10 gutloaded crickets. Just like a wild mouse isn;t goign to be as fattening as a CB mouse loaded with rodent chow.
ALL captive reptiles will grow faster than their wild counterparts. A coworker of mine, a herpetologist for decades, has done studies on various reptiles (real studies, in an accredited zoological institution). Corn snakes, if fed often, will be able to breed at 18 months of age. Wild corn snakes will usually breed at 3-5 years of age. Bog turtles in captivity will breed at 5 years of age. They never found gravid wild bog turtles under ten years old.
This rapid growth is associated with many side affects: earlierability to reproduce, larger clutch size, more frequent reproduction, and in some cases, short life spans.
In some animals, rapid growth has developmental side affects: "pinhead" snakes (a huge bodied snake wiht a tiny little head for its size), pyramiding in turtles and tortises, and increased chances of bone deformity in lizards and crocs. With increasing quantities of food, the animal must have increasing quantities of calcium and other nutrients. Increased growth makes achieving this balance more difficult - and in some cases, IMPOSSIBLE, resulting in inevitable problems.
Overfeeding a baby montane species is going to pose less probelms than some other species. Feeding a veiled a lot of food could result in them becomeing fullgrown at 5 months of age, as opposed to 12 months. With most montane species, that dramatic difference is not going to happen.
Adults will get fat - grossly fat - if allowed to eat their fill in captivity. I have a calyptratus that eats on average, less than 20 insects per week. If allowed to eat his fill, he'd eat more than that per day, in one sitting.
I also have a CB melleri, that could most likely eat 30-40 insects a day if I allowed her to. Instead, she gets 2-3, and is continuing to grow and gain weight.
Most otherwise "healthy' and well cared for chameleons I see die at around 3 years of age. Most of them were being allowed to eat their fill daily. Reptiles get fat, and don't cope wiht it as well as we do - obeciety shortens their lives by a large amount. Veileds can live to be over 10 years old. Fat veileds die in 3-4 years most of the time. For females, it's even worse - they start laying eggs at 4-6 months, and lay clutches every few months (massive clutches) and they die in 2-3 years. My females, kept thin and hungry (but perfectly healthy!), never lay more than 2 times a year.
