I always heard that diets don't work. It's a matter of changing your eating lifestyle or the weight comes back on.
In the end there's no way to get away from calories in vs calories out. The more sedentary your lifestyle, the less you should eat. The problem is that when you're sedentary it's easy and fun to eat!
I've been gaining weight since retirement. 2b, we both need a lifestyle change. A change of habits. Things we now eat regularly need to become treats. Treats we have now need to become more rare. And as Madge said, we need to get off our fat bums and exercise.