It is so frustrating when you have a strong-willed child who just will not cooperate. And it is even more upsetting when you read parenting books and the "experts" suggest contradictory strategies!
Most parenting books are based on the punishment model. You tell the child the correct their behavior, reward them (hopefully) if they do it, and punish them if they don't do it, to convince them to "do right" in the future. So if your child goes against your rules -- or in your words, "crosses the line" -- you punish them.
So, for example, if your child does not respond to your verbal limits and continues to throw his food around, you take the food away. Then, if he gets mad in response and hits you, you give him a timeout. Then, if that creates a power struggle (which it usually does because your child is emotionally worked up and resists the timeout), you add punishments like more time in timeout, or "consequences" -- meaning removal of privileges. If that doesn't work, you keep adding consequences until your child loses all his toys etc. If that doesn't work, ultimately, you have no way to assert your domination over your child except physical punishment. Of course, that might cow a 5 year old, but by the time they're eight, physical punishment no longer works, because your child can physically resist you.
That's when we see many families bring their child to therapy, because the child has become impossible, now that physical punishment no longer works. These kids think of themselves as bad people. They know they can't control themselves, because they have never had the help they needed to regulate their emotions. They may laugh on the outside but inside, they're hurting and lonely. Their relationship with their parents has been eroded. Their unruly emotions continue to drive their bad behavior. Unless therapy can repair the parent-child relationship -- which it usually does not -- the child's acting out gets worse. By the time they're twelve, they're looking for love in all the wrong places and vulnerable to "self-medicating" their rage, anxiety and depression with drugs and alcohol. They are children at risk.
But that's strong-willed children, who simply won't bow to our domination and keep resisting, even as we keep upping the ante. The punishment approach does work with more compliant children, which is why you feel like you're going crazy with your son while other people can take this approach and their kids cooperate. And it is also why the punishment model is still in use -- it works for the majority of kids.
By "works" I mean that for probably 60-70% of kids, you can raise them this way and they come out okay. Of course, as adults, they may need prozac, or be prone to fights with their coworkers, or procrastinate so they can't meet their goals, or have a hard time creating a peaceful marriage. That's because no one ever helped them with the emotions that drove them to misbehave to begin with. So they just stuffed those feelings. They pacify those upset feelings of shame and guilt and loneliness with food, or shopping, or screens or other little addictions. But as kids, they obey their parents, and try hard to be "good girls" and "good boys" -- and that gives them a certain amount of positive self-esteem from parental and social approval and from playing by the rules and thus "doing well." In other words, many kids raised this way function relatively well throughout their lives, even if they secretly feel inside like they aren't good enough or completely fulfilled.
So it sounds to me, Marnica, like you're running into problems because you don't have a compliant kid. Instead, you have a strong-willed, probably emotionally sensitive kid. So all that "conventional" advice you're getting is not going to work with a child like this. I'm sorry. I know it doesn't feel fair. But these kids have big emotions and they simply can't swallow them to obey us. They are begging for us to help them with their emotions, and until we do, they can't behave. Is this more trouble? Yes. But we don't get to choose the seeds we get. Our kids blossom into who they are -- roses with thorns or morning glories who only blossom in the light -- and our job is just to provide them the conditions they need to bloom. So I will tell you what I think is happening with your son and how you can stop fighting with him and help him bloom.
Let's start by considering how this scenario goes with a very emotionally sensitive, strong-willed kid. They have big feelings, meaning that they respond with big emotions to everything that happens. They pick up on your feelings, which further complicates things for them emotionally. They don't know how to work through those feelings, unfortunately. So they "act out." That just means they have feelings they can't articulate, so they act those feelings out. They might, for instance, look right at you, throw their food and laugh.
Why would they do such a thing? Usually, they have some big feelings of fear or hurt or disappointment that are bubbling up. Why would they have such feelings? Because all young humans do. By the time a child is 4.5, they know you might die. Or at least go away and not come back. They worry about whether they will make it to the bathroom on time, most of the time. They feel incompetent because they are worse at most things than most of the people (i.e., adults) around them. They feel powerless because they feel constantly pushed around. So they are lugging around a full backpack of yucky feelings -- fear, sadness, disappointment, shame, guilt.
What they need is help to "feel" those emotions. Because once humans feel their big emotions, those emotions simply evaporate. But until we are willing to feel our feelings, they stay with us, trapped, bubbling up and trying to surface. Unfortunately, those feelings make us feel terrible. Like throwing up, or peeing in our pants. Seriously, that is what big fear feels like. That's why people pee in their pants when they find themselves in front of a firing squad. And for young kids, as crazy as it sounds to us, life often feels like a big emergency, a matter of survival. So because kids will do anything not to feel those yucky feelings, they stuff them down. But the feelings are always looking to heal, so they keep bubbling up, especially when the child is either triggered, or conversely, feels safe enough to deal with the feelings.
So what do kids (and other humans) do, when those feelings bubble up? They feel under threat. They associate the feelings with whoever is nearby, like their parent or sibling. They do what all mammals do when they feel under threat -- fight, flight or freeze. With freeze, they try to numb themselves -- for instance, they might look blank, as if they have no remorse. With flight, they might take refuge in a screen. But most commonly, they start a fight. The best defense is a good offense. So your son looks right at you and throws his food. He would rather have that fight than feel those feelings.
So at that moment, you can stay rational and keep escalating your limit. But that leads, as you have discovered, to your running out of options.
If, instead, you remind yourself that your son needs help with his emotions, you can respond to the emotions that are driving his behavior. You can help him surface them and work through those tears and fears. Afterwards, he will be cooperative and flexible. Really! After kids are able to express some of those feelings that are so uncomfortable for them, they are so much better able to connect with us. And that's what makes them want to cooperate.
So how do you help your son work through his feelings? You create enough safety for him to be willing to feel the emotions. That means you don't send him off by himself, which gives him the message that he's all alone with his big, scary feelings. Instead, you set a clear limit on the hitting but you "help" him cry. So you empathize as you set the limit: "You are so mad at me....you can be as mad as you want, and cry as much as you want, but I won't let you hit me." You stay nearby, but not so close that he can hit you. If he does try to hit you, you hold his arms if you need to. But you keep breathing and reminding yourself that you're safe, so you don't get triggered yourself.
Hopefully, your son will feel safe enough to move past the rage and right into his tears. But since the two of you are in the habit of power struggles, he might not. He might keep trying to hit you. In that case, it's a sign that you need to increase safety even more, with your compassion in the moment, but also by strengthening your relationship with him in general. You do that through daily play that gets him laughing, and through making empathy your "go to" response to him. Think of this as preventive maintenance.
It would take a whole book to give you the tools and strategies for this, to stay calm, do daily preventive maintenance, and help him with his feelings. In fact, I have written that book, and it's easily available on Amazon -- Peaceful Parent, Happy Kids: How To Stop Yelling and Start Connecting. I think it would answer all your questions about how to stop the power struggles and help your son WANT to cooperate. I know that seems far-fetched to you right now, but that is because you are focused only on the limits and not on the empathy. Yes, of course kids needs limits -- he can't hit you or throw his food -- but you are missing an essential ingredient if you aren't setting those limits with empathy and helping your son process the emotions that are driving his bad behavior. If he doesn't get your help with his emotions, he doesn't learn to manage them, and if he can't manage his emotions, he can't manage his behavior. Defiance is not a discipline problem; it's a relationship problem -- he is showing you how alone he feels. Your son is acting like this because he needs help with his emotions and he doesn't trust that you're on his side to give him that help. You can change that, with your empathy and connection.
Finally, you ask, "there has to be some consequences for crossing the line doesn't there?" If by consequences, you mean punishment, I don't think so. Our goal is to nurture and lovingly guide our children. There is never any justification to intentionally hurt them (and that is the definition of punishment -- to intentionally cause pain in an attempt to influence someone to do things our way in the future.) We DO have influence with our children, but that influence comes from love and connection. When kids feel deeply connected, they will do anything to maintain that connection and they would never endanger that connection by going against us. In that kind of relationship, if our child crosses the line, we go after him and get him, using our loving connection to bring him back inside the bounds of loving conection. We don't cut him off with punishment.
Because with love, there is no line. There is only love.