Hi guys. I'm new here and I was hoping someone can help me.
I have a 9 year old Persian male cat, and the last time he was weighed he was 4.5 Kilos. At the time he was sick and had lost some weight. It's been about 3 weeks now and it looks like he had gained even more weight.

The vet told me that I should keep his weight at 3 Kilos and I'm trying to do it but at the same time, I don't want my cat to feel hungry.

I began to take notice of the way I used to feed him and I realized that I fed him over 6 times a day, each time I served him a 85g Whiskas Pouch.
I've read that Whiskas isn't good, but I've checked all the info recommended on several sites and Whiskas has everything.

For years all the cat ate was chicken and dry food, nothing wet until about 8 or 9 months ago. He was tested and the vet told me that he needed some wet food because he wasn't getting some vitamins so I started giving him some. He didn't like the canned food that much but went crazy over the pouches and I started giving him everything, not together, but I would give him a meal of dried food, then a meal of canned food, then a meal of pouch, etc... and I noticed that sometimes the food would barely be touched until I gave him the pouch, so I've only been giving him that about 5 times a day (maybe more) and there would be dry food sitting all day (which he also loved).

I've been reading a lot about how dry food gives cats kidney stones and it isn't as nutritious as the wet food, so now I rarely give him any. It's been strictly pouch food for the past 4 months or so but ever since the vet told me to get his weight down to 3 Kilos, I've been careful to feed him only 3 times a day, every 8 hours.

I want to switch him back to chicken because the vet told me it would help him lose weight but the problem is, he won't touch the chicken anymore and he would just wait for the pouch.

I need a way to make him start to lose weight, but at the same time not starve him.

Also, he's a very inactive cat. I've bought him some toys, and he would play with them for like 15 minutes a week or maybe less, and that is after I persuade him to play in the first place. I bought him a tree house that I haven't put together yet (because we're moving in about 2 months and I want to put it up in the new house.)
Can someone tell me how I can get him to be more active? It sure would help with losing weight.

Sorry for the long post, but I figured that the more info you guys have, the better advice you can give.

Additional questions:

1) 85g x 3 times a day = 255g. Is that too much or too little?

2) Am I harming my cat by feeding him pouch food only? He only likes 3 kinds which are Chicken, Lamb, and Beef. He doesn't like the sea food.