Spaying and neutering does change the metabolism of companion animals, so in most cases, they do not need as much food to maintain their weight as unspayed/unneutered animals. The problem is not with the animal - it is us. We just tend to overfeed our cats, and neutered/spayed cats are more apt to put on weight because of that.
As for laziness, again, the amount of exercise our cats receive and their activity levels are often dependent on us. If we do not give them opportunities for play and exercise, they can become couch potatoes just like some people.
My veterinarian recommended I spay my new kitten and she is only two months old. Is that safe?
Early spaying/neutering has been shown to be safe in multiple studies. It must be remembered that younger animals may need different anesthetics and are more prone to hypothermia (lower than normal body temperature) during surgery. But as long as procedures are modified to account for these differences, early neutering is very safe. In fact, animals neutered at a younger age often have faster recoveries than those neutered when they are older.
I was told I should let my cat go through one heat before I have her spayed. Is that what you recommend?
We recommend that cats be spayed before they have a heat. There are several reasons for this:
Any heat brings with it a chance your cat could become pregnant. This would adversely affect the health of a young cat.
A heat also brings with it the chance for accidents. Cats in heat try to leave their houses and yards to find mates and may be injured by other animals or hit by cars during their search.
Owners of females in heat also frequently have to deal with a sudden influx of male cats around the home and yard. These amorous visitors leave numerous droppings, and spray plants and trees with urine in an attempt to mark their new found territory, and can keep you up past 2 am with their howling.
A further reason for spaying cats is that cats who have been spayed have a 40-60% lower risk of developing mammary cancer than those who have not been spayed.