I see a lot of people posting about what they use for gutloading and feeding veiled chameleons, but are there fruits and veggies that should be avoided?
Major things to avoid: Broccoli, spinach, beets, and parsley, have large amounts of oxalic acids which bind calcium absorption. Lettuces (iceberg, redleaf, etc) and cabbage do not have any significant nutritional value. Also, avoid things like dog food, cat food, and fish flakes which are high in animal proteins which can cause kidney damage.
Overall you want to avoid veggies high in oxalates, goitrogens or higher in phosphorus than calcium. The link in my signature has a chart with the basic contents of common fruits and veggies you can use as a guide.