Ditch processed meat and other foods, refined sugar, bread and pastas, and alcohol, especially beer. Or at least minimise it.

Make sure you eat recommended daily calorie intake based on your physical activity and don't go over it.

Light to moderate physical activity (walking instead of using elevators, short stretching exercises, short walks...) in case you're sedentary.

Try not to eat in the night. Set the supper time (optimally around 6PM) and don't eat anything till the next morning.

Drink lots of water anyways. Brain often mistakes thirst for hunger and you eat when you should just drink water.

Be patient. You didn't gain it overnight and you won't lose it overnight either. Healthiest tempo is one kilogram/ half a pound per week.