It is, in essence, a totally different way of "dancing" through your life with food, hence the word lead.  It means you decide and provide, at least one day in advance, (never "in the moment") what you will be eating every day—basically for the rest of your life. It is how you engineer emergencies and emotions out of your food decisions. It is how you decide to eat mindfully through every situation that comes your way. It is how you experience feeling socially/emotionally awkward about this sometimes and learn to ride and abide those and any other uncomfortable feelings without returning to self-abusive behavior choices.

In time (in years, not weeks or months), if you lead with the diet it will slowly become a self-supporting habit, an emotional anchor, a way you love and take care of yourself, which in turn helps make you BETTER able to love and take care of the other precious people in your life.

It is also how you KEEP weight off forever. Nobody ever regained their weight because they experienced difficult situations or feelings. They regained it because they changed their eating choices, in response to those struggles.

Regain happens only when you fail to lead with the diet.