When needed, how do you lose weight?

When I broke my ankle twelve months ago my weight increased by 15kg - 33lb through inactivity.
Very easy to put on weight, not so easy to remove it. Especially as we age and joints become problematic.
I have started to attempt shedding buy replacing my usual Macca's breakfast with a fruit smoothie.
There has been the necessity to add another hole to my belt. Having shed 5kg - 11lb - over the previous month.
Not really going to exercise, just use dietary practices for now.