What affects a cat's weight?

• Breed: Some breeds are naturally larger than your average cat including Maine Coon
  Norwegian Forest Cat, and the Siberian. Similarly there are also small breeds of cats like Siamese, Cornish Rex, and the Munchkin
• Age: Kittens will of course weigh much less than an adult cat. Senior cats can start to weigh less as their muscles begin to deteriorate due to their age
• If a cat is neutered/spayed: Neutered cats tend to put on weight if fed the same diet as before they had the procedure. This is because their metabolic rate and energy levels can dip after neutering/spaying
• If they are an outdoor/indoor cat: Outdoor cats may hunt prey and patrol their neighbourhood which uses energy. Indoor cats typically prefer to laze around so they aren’t using up the energy. It’s important that indoor cats are given opportunities to be active
• Sex: Male cats are generally bigger and heavier than female cats particularly if they weren’t neutered before they reached sexual maturity (4 months old)
• Health conditions: For instance an underactive thyroid gland can cause cats to gain weight
  and heart disease and feline infectious peritonitis (FIP) can cause fluid retention. Similarly
  health conditions like having worms, diabetes and enlarged and overactive thyroid can cause cats to lose weight 

How much should a cat weight guide.