Many iguana owners, upon seeing how much their juvenile and adult iguanas can eat, wonder if there is such a thing as too much - or overfeeding - their iguanas. Fortunately for the iguanas, so long as they are being fed a properly constructed diet, you can't overfeed them. In the case of omnivorous iguanas, such as Cyclura n. nubila, chuckwallas (Sauromalus) or the spiny-tailed iguanas (Ctenosaura), you need to watch the amount of animal prey they are given, but they can have unlimited access to the herbivorous part of their diet.

Many iguanids, such as the green iguana, come from areas where quality food - or food period - is scarce at certain times of year, so feeding drops off considerably during this period (such as the dry season throughout the green iguana range) and what feeding is done is on plants that are very low in nutrition. To conserve energy during this period, iguanids don't move around much, spending their days basking, lounging and sleeping.

During breeding season, males may go off food completely for one or more months, or just taking in a few mouthfuls of food every couple of days. Gravid females become so filled with eggs their second month that they don't have room for more than a mouthful of greens now and then.

During shedding periods, many reptiles, iguanids included, go off their feed for a couple days.

The heavy feeding that the iguanas do during the spring and summer months serves to not only maintain health and permit natural growth, it also builds up their fat pads (which run along the back and sides) and fill out the males' jowls off of which they will draw energy to sustain them through the non-feeding times when they are shedding, in breeding season, and during the winter months.