Wanting to loose weight does not mean you can, and even if you do actually manage to beat the battle, it can come back. it takes more than want, it takes a lot of effort to loose weight, and time and thought. You need to pre-empt situations that you would normally over eat, figure out how you can work around those (ie going to a party and not overeating, depression, anxiety, stress), as well as your every day to day diet changes.
And even if you mess up, its very hard to get back on the wagon due to feelings of failure and 'ahh fuckit' (very strong feeling that one!)
This is why most kitset diets work, and what works for one person may never work for another . This is why shakes and other things don't work so well for people, they don't help with the state of mind
I completely agree with @wishes. Simply wanting to lose weight is not usually enough. There is SO much emotional and psychological aspects that go into losing weight and the more weight you need to lose, the more impact those emotional and psychological aspects have.
Two areas I have found people to have the biggest problems with are 1) Planning (like mentioned above, going to parties or planning your meals for the week) and 2) Not using food for comfort/reward. Both of those have to do with your psychological and emotional mindset and they both have to do with nutrition which plays a HUGE role in your weight loss goals.
Get those 2 things in check and you'll be WAY ahead of most
On a side not, congrats @wishes for your huge weight loss!! I just saw your progress under your post and that is awesome! Keep up the great work!