Protecting your self-esteem is important. High self-esteem probably means that you are likely to succeed in life.
If protecting your self-esteem is too important, you might shift your goal away from well-planned for, self-regulating diet and exercise to necessary inflation or restoration of your self-esteem. When this occurs, your weight loss efforts suffer.
Playing it safe is a way of protecting your self-esteem. If the stakes are high like they are for you in dieting and losing weight and you aim for that desired weight loss goal and fail, you could feel humiliated and not try again. You wouldn't want to appear to be a fool and incompetent, not even to yourself. It could be most important to you to do anything to save face.
So if low self-esteem is your problem, you'll definitely have to add working on your self-esteem to your weight loss diet plan.