Quality of food is a very important thing to consider. Feeding will be everyday duty so WHAT and HOW MUCH to feed will be the principal point of iguana care. It is not too much to say that killing your iguana or making them alive depends on the variety of food you prepare.
Some people say "My iguana loves hamburger so I am giving them everyday". And some people feeds meal worm or crickets everyday after they heard the wrong information that iguanas are carnivorous when youth.
It is certain that iguanas will eat quite various foods if you feed them when they are hungry. But be sure not to hastily think that it is a good food for them if they love it. In most of the cases, they are bad and if you feed only foods they love, you might be stepping into a trouble.
They can only have an access to the food you prepare, so you can never be too strict when choosing their food. Think and study about nutrition, minerals, vitamins, and balance. Iguanas are actually a strong animal if you give them good environment and good food, but they will not survive over an year if your food is wrong or monotypic.In 1960's, there was an inaccurate report telling that juvenile iguanas are omnivorous and they will shift to herbivorous as they get mature. Lately, green iguanas in wild are believed that they are completely herbivorous from juvenile to adult. This is based on reports of many field survay and analysis of stomach contents of wild iguanas. Of course they may eat insects or its eggs which are on the plant leaves accedentaly but their main targets are variety of leafy greens.
So in captivity, we also can suggest to feed only plant matters. Animal matters such as meat, insects, cheese, eggs, etc. are not recommended. Canned dog food or cat food or other food for carnivorous animal may be easier to feed and iguanas might like them but this will definitely brings your iguana into health problem. Less than 10% of animal protein may be all right but I suggest not to feed over dosage. We have been feeding them only plant matters for over 6 years for 13 iguanas and they are all healthy. We also succeeded to reproduce and this baby (Bingo) was also fed only plant matters and laid 42 eggs when 1 year and 10 month old. Therefore, we also concluded that animal matter is not nescessary for green iguanas.
Best way of feeding your iguana is to provide variety of calcium rich greens. If you were already feeding wrong type of foods, switch to various plant materials as soon as possible. If you were feeding some kind of dog food or cat food, first they may not like to eat plant materials. But they will start to eat when they get hungry. It might take several days but they will not die by not eating for couple of days. Be patient. It will be better for them.
Tip : Provide many variety of plant matters Vegetable matter usually takes longer time to digest. Similar to those of other herbivorous animals, digestive system of iguanas are known that they are using the effect of intestinal microbe. So they need to warm up their body for better digestion. It is recommended to feed your iguana before noon so that they can warm themselves before they sleep. If you are a worker, it is better to feed them in the morning than feeding them late at night.
(Continue : Still working on English page. English is difficult for us and takes time.)