If you are constantly criticizing your actions and hating your behaviors, you're judging yourself. When there's judgment, there's no room for learning. You miss whatever the lesson is trying to teach you. It is these lessons that often serve as our biggest opportunities to see where and how we need to change.
Learning to trust myself has allowed me to be happy in my body in a way I never imagined possible. But it required that I stop judging my happiness by looking in the mirror and comparing my body to other women's bodies. It required that I look inside, listen to and trust my body, and find happiness by turning away from appearance and toward my heart.
When you're struggling with food or battling your weight, it's easy to self-sabotage. With constant self-criticism, berating our bodies, and punishing ourselves for things we did/didn't do, we often become our own worst enemies. But the things we are telling ourselves (subconsciously or consciously) can do us more harm than good.
It's not that we lack self-discipline or willpower to be successful. The problem is that dieting couldn't be more opposite to how we're evolutionarily designed to survive and function best. Could you ever imagine our distant ancestors going against their biological drive for survival by purposefully eating less food when it was available?