There are several things you can do to help your cat get back down to a healthy weight.
The first thing you want to do is get Jake a check up. Your vet can tell you how much he needs to lose, and how long it should take for him to reach his healthy weight. It is very dangerous for an overweight cat to lose weight too fast.
There are special prescription foods that are very high in protein, 50% I think, that your vet may want to prescribe. These high protein foods should only be fed under your vet's supervision, and are not meant for long term use. Not all cats need these.
If no special food is required, he should be on as high a quality of food as you can afford. Avoid foods with a lot of grains and by-products listed under the ingredients. A meat protein should be the first listed ingredient, and a meat meal the second.
Once you have a diet plan to follow, it is also important for him to get plenty of exercise. Sometimes a cat that is not used to a lot of vigorous play will be slow to get motivated. Don't give up though, because as he loses, he'll feel more energetic and want to move more.
The more a cat plays, the more he'll want to play. Interactive games are very important. Pay close attention, he will show you what he likes best.
I advise getting down on the floor with him every night at about the same time. He may not seem interested at first, but after a week or two he'll come to realize that this is a very special time for him and you, and he'll look forward to Game Time with you.
Offer a variety of games, don't become discouraged if he isn't lively right away. For instance, try to play Chase the Crumpled Paper for two or thee days in a row. If he's still not interested, the next night try a wand toy Game. (aka String On A Stick). A few days later bring out the Crumpled Paper again. And so on.
Cardboard Box Forts and Paper Bag Forts and Newspaper Tents can help stimulate his imagination, too. (interactive games stimulate mentally as well as physically)
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