Cats strange behavior /diet

Question
I have a 14 year old male tabby cat. He is old, nasty and cranky but I love him. I have had him since he was 8 weeks old. Since, the age of 5, he has been acting out a strange behavior. This behavior is, he constantly throws up if I am late in feeding him his meals and/or... he will throw up if he gets upset with one of us family members such as teasing or ruffing him up a little. He will especially make sure when he throws up, it will land on a purse or a sweater which is laying on the floor. He is obese. I feed him a Nine Lives Active Formula, it's the hard kibble kind. I did through out the years have had him on diet food but he still didn't loose weight. He is moving much slower now and I think he has a little arthritis in his legs. Every time, I pick him up his stomach is hard as a rock?? Once we had him on soft food-canned when he was 2 years old for about 1 year and that is when the weight really started to increase. Is there anything you can suggest or help with so I can get his behavior and diet in check??
Thank you,
Summer

Answer
Believe it or not Summer, I have known cats that were bulimic eaters. There are also cats with very sensitive stomachs and he sounds like one of them. He is an emotional eater apparently, and an emotional vomiter.

What you are feeding him at the age of 14 is not healthy for his age or his weight. This type of food is full of fat and other imbalances that will only upset his system more.

There are two ways to reduce the weight on a cat. The first one is to get him on a very low calorie but nutritionally complete diet. You will not find these at the grocery store. If you are serious about his weight loss, then go to the vet and get him a bag of Hills R/D. It is one of the few foods proven to reduce a cats weight without creating hepatic lipidosis which can be fatal very fast.
The other way is to exercise them more along with the diet. It's just like us- move more and eat less. But unlike us, cats that lose weight incorrectly or two quickly are at risk of developing hepatic lipidosis.  This is when the liver gets filled with fat cells and cannot function.

There are no low calorie diets on the market in the stores. They may claim to be low calorie but if you knew how to compare them to an actual diet  food you could see that they are not. The only one that can be bought at a pet store that is a lower calorie diet and still has the full nutrient value a cat needs in it is Science Diet Feline Adult Light formula.

You must switch this cat over very slowly to any new food. You have to measure this food out correctly- that means an 8 oz. cup used to measure the food and not just throw a bowl full of food out for him.

He is cranky because he hurts. He is the equivalent of a 400lb person. Your joints and back would hurt too. He may be older but if you persevere with his diet and try and get him to play some, he will lose weight. Believe me, we have seen hundreds of dogs and cats regain their lives through reducing diets. So get the R/D to start him off right and let me know how he does in about a month or two.