I think 17 mo is old enough to understand the basics of table behavior...one of these being no throwing food. I did what ks6 does. Only give a few bites at a time and if the throwing starts, say "I see you're all done" and end the meal until the next snack or mealtime. It's hard to do and stick to your guns, especially if you know a meltdown is coming or you're worried about him eating enoug!