You will need to find a diet plan that works. Swimming may be a possibility (or walking in a pool) as this will reduce the stress on your joints. Please look into this.
Given you are morbidly obese, it may be a good idea to work with a dietician if you can. else there are some decent online diet plans available.
You might be more successful with smaller changes. Start by cutting out junk food. ie. soft drinks and candies. Try to make sure that all of your meals include vegetables (at least half the plate should be vegetables) and some protein. Try to avoid deep fried foods.
The best way to do this is don't buy any foods that you know you can't control your eating with. For me this includes things like white bread.
Try changing your foods from more refined to those with more fiber. ie. whole grain bread instead of white. Brown rice instead of white. These are more filling and you'll be likely to eat less.
Start every meal with 1 - 2 glasses of water, or a bowl of broth type vegetable soup. these will help fill you up without adding calories.
Hope this helps.
thanks for all the suggestions I will try them again thank you so much