It's interesting that you mentioned your parents used to make you eat everything on your plate. This is one of the most common subconscious beliefs that stops people from maintaining a healthy weight; the belief 'I have to eat everything on my plate'.
From birth to about the age of 8 years, our conscious critical thinking mind has not yet formed. This is the part of your mind that (as an adult) allows you to decide what you are going to believe. (For example, if someone were to come up to you and say: 'You are a difficult person', then as an adult you have the ability to say: 'No, that's NOT true. I don't accept that.') So before age 8, everything our parents, teachers and other people in authority say to us goes in as absolute fact and forms the basis of our subconscious belief systems.
From my experience with clients these beliefs cause a lot of self-sabotage because your subconscious mind brings into your awareness everything that supports your beliefs. Therefore, if you continually say (out loud or silently) 'I am always hungry', then your subconscious will store and re-affirm this as a belief; and therefore you WILL eat more than you need. Here are some other really common beliefs to watch out for:
'I never finish what I start';
'I am an 'ALL or NOTHING' person (IE: If I have one Ti Tam I have to finish the whole packet';
'I dont have time...' (to prepare healthy meals or exercise);
'I have always struggled with my weight' (therefore alwayswill...);
'I am weak willed';
'If it's free I have to eat it'
Watch what you say to yourself and about yourself and this will help you to get rid of unwanted beliefs. Speak in positive terms about yourself and your life, and focus on what you want, not what you don't want (EG: Instead of thinking: 'I'm sick of being overweight', say: 'I look fowrad to being slim'.)
Hope this helps