Banta slö katt

Hey! I try to lose my cat while not being hungry. He is castrated and innate, we have tried different feeds for him as metabolic and also Hills R / D and Satiety Support SAT 34. He is lethargic and just wants to eat and sleep. He kneel bowls also jump out of joint which I have searched for at my vet in hessselby. He now weighs 8.15 kg and is gaining weight all the time although I don't give him as much food. According to the veterinarian, he is in the risk group of having diabetes and other diseases. He is 8 years old. and do not want to go out in harness or play with feather lashes. in 2 weeks we will weigh him again at vets. Is there any medicine to increase his fat distribution? Which feed is best for him? a big thank you in advance! Best regards Daniel