A cat who is sick or has been neglected may wind up being significantly underweight as a result of his circumstances. Because your cat's health can be affected negatively by being underweight for a long period of time, your job as a pet owner is to help your cat gain the weight he needs in a healthy and safe manner.
Visit Your Veterinarian
Your veterinarian can best recommend an effective and healthy weight gain plan for your cat. Before you attempt to change or alter your cat's diet in any way, you need to take him to the veterinarian for a medical examination. A cat who is too thin will have visible ribs, no palpable fat. The lumbar vertebrae will be visible and the abdomen will appear to tuck up clearly. Your veterinarian will determine how underweight your cat is and how much weight he needs to gain to be healthy. Your veterinarian also will be able to tell you whether an underlying medical condition is responsible for your cat's weight loss.
Calculating Weight Gain
When it comes to weight gain, your cat really isn't all that different from you. If a normal, healthy cat eats more calories than his body needs to maintain his current condition, he will gain weight. A normal adult cat who weighs between 8 and 10 pounds will need to take in between 180 and 220 calories a day to maintain his weight. To safely gain weight, that the same cat gradually would need to increase his daily calorie intake 25 percent. This means that your cat would need to consume approximately 230 to 270 calories per a day.
Emaciated or Starved Cats
UC Davis Koret Shelter Medicine Program recommends limiting the amount of food a severely underweight or emaciated cat receives when you are beginning a program to help him gain weight. Introducing too much food or food that is too rich to a starved cat's system can cause serious health problems. If your cat has not been eating regularly, your veterinarian should help you determine how many calories he can receive per meal. Your veterinarian may suggest limiting a cat's calorie intake at the beginning of any feeding program if he has not been eating well prior. An emaciated cat may require as much as a 50 percent reduction from the normal amount of calories he would receive.
Feeding Your Underweight Cat
Once your veterinarian has decided which type of food will best meet your pet's needs, you will need to look at the number of calories in that food and split your cat's required daily caloric needs into multiple small meals. Feed your cat as many as six small meals per a day, ensuring that he receives the required number of calories he needs to gain weight. Decrease the number of meals and increase the portions over the course of time as your cat becomes used to the amounts. Visit with your veterinarian regularly as your cat progresses and adjust your feeding plan as your veterinarian recommends.