Cats that eat too fast can make themselves sick and end up regurgitating what they just ate.
Cats that eat too much can become overweight and unhealthy.
While there can be a number of behavioral reasons your cat may eat too fast or too much, it could also have to do with a medical problem or the diet itself not providing enough or the right kind of nutrients. You may want to look into any non-behavioral possibilities before trying a behavioral solution.
There are two obvious ways to have your cat eat slower or eat less if it's a behavioral issue.
Instead of giving your cat one large portion all at once you could break it up into multiple smaller portions. Your cat may still quickly devour the smaller portions but you're creating a pause between those portions.
Your inconvenience is having to perform multiple feedings and maybe face your cat's displeasure with not having enough. However, there are products that can help.
An interactive feeder doesn't have to replace your cat's normal meals but can introduce more options by slowing how quickly your cat eats, offering a variety of treat alternatives in addition to the usual meal, and adding stimulating activities to your cat's daily routine.
The basic interactive feeder below requires your cat use its paws to fish out the food from between the protrusions.
With the food tree the dry food is pulled out of the sides but can also drop down between three different levels.
Similar to the food tree is the tunnel feeder which drops treats into tunnels where your cat has to fish them out.
The multi feeder below allows you to serve your cat wet food directly and place dry food in the hole for your cat to fish out with its paw.
Another interactive feeder comes in the form of a meal dispensing ball for your cat to play with.
There are some gravity fed automatic cat feeders that refill your cat's bowl and let your cat eat as much as it wants. That's OK for a cat with good self-control about eating. However, what's needed for a cat that eats too quickly or too much is an automatic feeder that controls the portions.
With the automatic cat feeder below you can set up to 6 different mealtimes per day each with their own setting for portion amount. There's also a slow feed setting that pauses a set number of minutes between portions when delivering a meal.
There is also a Wi-Fi version of this product that you can program and operate from your smart phone. It also gives you up to 10 meal settings per day instead of 6.
If you want to give your cat wet food instead of or in addition to dry food then you'll need to go with an automatic feeder that rotates instead of a gravity fed one.
The cat feeder below doesn't automatically portion out food from a container but instead has 5 sections that are exposed according to the timer. You can put whatever you want into each section (e.g., wet food, dry food, treats, medicine, etc.). It also has ice-packs underneath that can be used to keep it cool.