Ok, you need to do many of these things all at the same time. If done separately, they won't work!!
Drink lots of water
Really limit your food variety. I mean eat the same thing for breakfast, lunch and dinner for days, weeks if you have to. eg weetabix for b fast, tuna (no mayo) sandwich for lunch and salad for dinner. I would eat this combo for about 3 weeks
Literally RUN around your house. run upstairs, grab washing, run downstairs, put it by washing machine, run upstairs, clean bathroom, run downstairs, put washing on, run upstairs, make bedsm run downstairs, drink glass of water, run upstairs,....you get the idea. Do not rest at all until a certain time of day. My time would be about 6.00pm
Another way is to eat the same thing all day but in very small quantities. I used to eat a swiss roll all day ( a little bit at a time) That's it until dinner and then have a proper dinner. the weight dropped off
I realise all of this is very unconventional, but it does work.
Also, I should add that I don't do this all of the time and think I would feel terrible if I did. I have a healthy, balanced approach normally and I think that doing this mad stuff occasionally doesn't do me that much harm