I won't give you my life story, but just a couple of things to hopefully show I do know where you're coming from. I've been Agoraphobic since 17, now 41, and 5 years ago was size 22 jeans and about 26 top, my BMI was 38.5, medically obese. I've done all the see saw weight loss and diets, but what really changed was when I changed my whole idea of food and eating.
For me, now a size 10 woohoo, its about compromise, if I want a curry tonight, I realise I need to have salad for dinner
I bargain and calorie count everything. Obviously it's mega hard at first, especially without being able to go out or exercise, but one trick which might help, make your meal as usual, then take just a third off the plate, pop it onto a little plate or dish and leave it in the kitchen. I used to try this and tell myself "look, if you're still hungry when you've emptied the 2/3rds plate, then just go get the other 3rd" but I rarely did, woohoo.
Another great tip, is find low calorie stuff you LIKE. I used to buy apples and week upon week sling the bag full away, because I really don't like apples, but grapes, now I can eat a punnet a day if allowed
Plain popped corn with nothing on some people like and you can graze on that, low calorie hot choccy will sometimes stop me having a sweet treat, get fun-size bars of the choccy you like.
Just try and work with yourself, realise your weak spots, maybe it's a ruby murray once a week, so 'save up' calories accross the other 6 days so you can have it guilt free
The other thing I can strongly advise, is really work out WHY you want to do it, the reason that will keep you going, or getting back on the wagon when you've fallen off, work out what it is and stick it on a sheet of A4 coloured card in every room of your house. For me, it wasn't the health, it wasn't the fact I was horrible and felt like a monster, I met a new partner, and when he took his shirt off, my legs went jelly, and it hit me "I want HIM to look at me and HIS legs go jelly" and that kept me going, silly huh
Hope to goodness I haven't patronised you, but no, give these shystery plans a miss, change things slowly, little by little and before you know it you'll be like me, who CHOSE steamed veggies for tea over a chinese takeaway, I mean...really??!?! Even I struggle to believe I did that