large kibble diet food

Our cat has been on dry food (hills oral care) since we rescued him 4 years ago. he is getting overweight and we have tried dry diet foods but he doesn't like the small kibble! Is there a large kibble dry diet food out there?

All of the kibble I've encountered is small, but if you're concerned about weight, I would reduce and/or get rid of kibble altogether. Kibble contains more carbohydrates than wet foods, so it's easier to pack on the pounds. Even high protein, low carb kibbles are very calorie-dense and so I wouldn't recommend even a high end kibble for cats who need to lose weight. "Diet" formulas are largely a gimmick and I find the quality of most diet formulas less than stellar.

If you look at the calorie and carb counts for the dry food you're currently feeding vs something like a wet food, there's a big difference. The high end dry food I use as a treat is about 120 calories per ounce (0.125 cup), and it's only 13.8% carbs which is really, really good for a dry food IMO. It looks like the oral care formula is 112 calories per ounce and 16.5% carbs. The wet food I feed, on the other hand is 28 calories per ounce and it's 2% carbs. The water is already built into the wet food, so cats can feel more satiated with a more substantial feeling meal than eating a load of dry and not really feeling full until they drink some water (think eating a bag of dry chips vs a stew, and how full you feel after eating each one without having a drink with it).

If you can, I would introduce wet food as a part of his daily routine. If he prefers the bigger pieces, he may like chunked wet food. These two articles can help with transitioning:

Transitioning Free-Fed Kibble Kitties to Timed Meals

Transitioning Your Cat from Kibble to a New Type of Food (Canned, Raw, or Homemade)

Most cats can lose weight without changing foods. Measure out his food for the day and divide it into two or three meals. Don't leave the food down between meals, and especially not overnight. Slowly, he will begin to lose the weight.

Solid Gold Katz-n-Flocken, Royal Canin Oral Sensitive, Royal Canin Indoor, Science Diet Indor, Science Diet Hairball all have larger kibbles, but you should be fine with what you have.

Mouse is also fed on the large, oral care kibble: now he is approaching 4 years old and somewhat less active than he was as a youngster I have to be extra strict with the rations or he quickly shows the non-essential snacking around his middle.  That said, he also quickly sheds this as soon as I get everyone in the apartment to behave and stick to the measured out daily allowance for him.  I like to keep his feeding active as well and will throw the large kibble for him to chase and place in boxes for him to seek out so he doesn't just see food as something sitting waiting for him in a bowl. The larger kibble size is handy for doing this but you do have to be careful and make sure none is left laying about on the floor to go stale.

I haven't seen any other kibble with similar design to the oral prescription, I guess because that is part of how it works with the cat having to crunch in to the biscuits rather than pick up and swallow like they do with other dried foods.  

If your cat enjoys the crunching and chewing it might be worth looking in the Raw and Homemade section too as there could be other options there as well.  If feeding oral kibble because of a history of dental issues then it is interesting to look at how some members here have found introducing this type of feeding has helped.  Note - I haven't done this my self though.  http://www.thecatsite.com/f/65/raw-home-cooked-cat-food