I have lost and gained weight many times over the years. What I am now realizing is that every time I gain weight back, it is for the same reason: I allowed myself to be unconscious.
I decided to diet, felt motivated, lost weight. Then, at some point, I said to myself, "I've had a hard day," or, "I don't want to track my food," or, "I'll get back on track tomorrow." I gave myself permission to eat what I want, as much as I want. I decided to let myself eat the whole [whatever]. I did it for days, weeks, or months. This is the common thread to my past weight gains.
So no more going unconscious for me! If I have had a rough day, I am going to talk with someone about it, or journal about it. Eating unhealthy food won't change my bad day. It will make me feel better, but only briefly. Gaining weight is the consequence of this, and that never feels good.
Turning to food when I'm anxious, worried, lonely, bored, tired, etc, is a bad habit that I need to break. Difficult feelings will always be there. I need to acknowledge them and work through them, instead of trying to tune them out with food.
Ultimately, if I want to lose weight and keep it off for life, I need to commit to being - and staying - conscious.