How to put my cat on a diet?

My cat was originally a stray and was very skinny when we found him. We then got him fixed and ever since then he has gained a lot of weight. He seems to eat food for comfort or when he is happy (he wants to eat after we pet him, which is a lot of the time)

Anyways we have 3 other healthy sized cats which is why it is hard to put him on a diet. We have tried science diet weight control for all of the cats but it doesn't seem to really help, is there any way to keep him from eating without depriving the other cats of the food we leave out? We can't watch him 24/7.

We have also tried exercising him with a laser pointer and his favorite toy stick thing but it doesn't seem to help. When we took him to the vet for his last shots the doctor didn't say anything about his weight but he is about 25 pounds now. What can I do that will actually work to help him lose weight?

My advice would be to switch to canned only, as it is more calorie dense, generally has fewer to no grains and all cats benefit from the extra moisture.

If, for whatever reason, canned food is something you cannot do, I suggest staying away from "indoor, weight control" type foods, they really don't work, all they have is added fiber, it's a marketing ploy.

Try looking for a mid level to high level premium dry with no to low carbs and good, quality meats as protein sources instead of grain glutens for protein.

Cats have zero use for carbs and generally, it's the carbs that add the weight on them.

I have three, healthy weight cats for example, fed primarily dry in a hopper style feeder (free fed).

I feed Taste of the Wild grain free.

Not a high level premium by any standard, but it costs about the same as a like sized bag of Purina Cat Chow.

The bonus is that with calorie dense foods, they will feel full on less which means they end up eating less.

I would schedule feed (putting out food twice a day, rather than free feeding, which is leaving food out all day.)  If you are already schedule feeding, great.  I would also switch to canned, if possible.  I"ve found with scheduled feedings of the appropriate amount of canned food it is nearly impossible to have an overweight cat.  My three are very happy and healthy with this routine.  (And they never seem overly hungry or deprived because the meaty canned food is so satisfying.)  Good luck.