I lost a lot of weight in 2012-14, which has partly been regained 10 years late, though I’m not as big.
It’s long-term habits which make long-term changes.
They’ve GOT to be sustainable, practical, affordable and palatable. What will make the difference to weight on 31 December is how you eat in the 45 weeks of the year which are not Xmas, New Year, birthdays, special occasions, hotel stays etc. Enjoy those without guilt and otherwise make rules you mostly keep.
Don’t eat food you don’t like. Waste of calories unless somebody will get offended or this is the only available food and you’re ravenous.
Limit portion sizes of protein foods to supermarket sized suggestions. That is ENOUGH!
Limit carbs to small portions
Don’t drink sugar
Enjoy TINY portions of top-class treats - go for quality, not quantity
Get used to being a bit hungry (not ravenous) it won’t kill you!
Try to wait at least 4 hours between feeds unless on a long bike ride.
Try to avoid processed & artificial foods.
Living on a diet of steak, salad and strawberries will lose you weight but isn’t too good for the wallet or the planet; tastes nice though!