Thanks for the responses, some more info as requested. I am turning 50 in a few months......
Thanks for the extra info.
At 50, your metabolism is taking some major slugs now. Being unable to do more than walk on those knees means you'd need to do clever cardio if you wanted to up the rate using exercise, and that would mean a lot of ground based bodyweight exercises and floor/mat based movements. Do low impact cardio classes appeal? How about walking with some weights, or a weighted vest? Easier in winter under a larger parka and not feel stupid.
Your gym program sounds great though and I'm glad you are already doing it, which you hadn't originally mentioned - its fantastic for your bone strength and to slow the onset of muscle wasteage, so keep that going as long as you can. The older we get, the more important this will be to stave off the inevitable downsides. And it's a staple in a weight management program of course. I wouldn't increase your program markedly, unless you want to add real muscle mass. Remembering though, that is harder for us at this age without a major investment in time and diet. Your call.
You've already lost 5kg through a few simple changes and as some have already noted, simple changes are often all that's needed. You have to enjoy your life, and cutting the odd boozy night out completely at our age without any attributed health concerns is just stoopid - you want to enter the last half of your life with a smile on your face, not a permanent grimace, after all !
So keep going with the cleaner diet - as you study it more, you'll see more areas where you can fix little things. Say, halve (or remove) the sugar in your tea and coffee, or cut out cakes or sweets during breaks with the same... things will pop out at you. Try natural fat burners, like lemon/cinnamon in teas, and chillis and peppers in your large meals. Anything that kicks the metabolism up a gear.
Certainly turning more towards a more traditional Asian/Japanese diet (virtually no processed sugars in their natural diet, lots of lean meats and egss for protein, rice as their only carb, not bread, moderate alcohol, green or black teas, plenty of veg and some fruit) will make a huge difference, if you and your lifestyle can stomach it.
Keep moving though. That's the secret.