Trust is everything, and it's created through repeated action. Doing the new behaviors, facing the scary thoughts, and seeing that everything is still ok. You can't decide in your mind, "ok, I trust now, problem solved." Or, "I'm not going to take action until I trust." That means never taking the steps necessary to experience the positive mental shift. Each time you try something new and learn from it, your confidence grows. Then you trust. Then it's real and not hypothetical.
It's not, "If I don't trust, I can't do this." Nooooobody who has restricted for years trusts that not dieting is going to be ok. You've kept yourself in chains all this time by actively telling yourself the opposite. "If I eat this, terrible things will happen. If I don't do that, terrible things will happen." It's fear and negativity all day long. Even when we're doing restriction "right" there's always the fear that it can't last, and the horrible story about what will happen as a result.
See the problem there? So, when you eat what you actually want for dinner, and don't restrict the next morning, diet brain goes INSANE, but that's what you've programed it to do. Now, we're going to teach it a new way of being. The more you do the new behaviors that you want and react with kindness and curiosity instead of guilt and fear, the more your brain is going to dial down the panic alarm and begin to turn up the trust.