Summarize this article in one sentence.
Weight loss from a calorie-controlled diet involves following a simple equation: the calories in versus the calories out equals weight loss or gain. Therefore, if your cat consumes more calories than she burns off in a day, she will gain weight. Thus to get the cat to lose she must take in slightly less than her daily needs. This option means counting your cat’s calories as you switch her to the reduced diet. Veterinarians recommend that you feed your cat 75 to 80 percent of the resting energy requirements for her ideal weight. This amount should help your cat lose weight at a healthy pace of one to two percent of her body weight each week. You should consult your vet for the exact caloric amount, but approximate amounts are:  180 calories/day for an ideal weight of eight pounds 210 calories/day for an ideal weight of ten pounds 230 calories/day for an ideal weight of twelve pounds You may have difficulty achieving this caloric intake with a standard, calorie-dense cat food simply because it’ll be much less food. Your cat especially won’t appreciate it. A formula specifically meant to help with weight reduction in cats will be low in calories and high in fiber, allowing your cat to eat nearly the same amount of food per day while still achieving the desired reduction in calories.  The cutback in a standard food will leave your cat feeling hungry and underfed, which means she’ll both pester you for more food and her body’s metabolism may slow due to the perception of underfeeding, which will make it harder for her to lose weight.  Your veterinarian will determine the best weight loss formula for your cat. Options include Hills R/D and Purina OM. These formulas also often contain L-carnitine, which is a supplement that can encourage your cat’s body to burn off fat instead of lean muscle. Use a kitchen scale when measuring instead of a dry measuring cup in order to be more precise. Weigh your cat and record the weight on a weekly basis. It is perfectly normal for your cat to hit plateaus in the process where she might stop losing weight before the target weight. Consult your vet about reducing the caloric intake another five to ten percent for further results. Those attending a pet weight watchers are much more likely to reach their target weight than those not attending. This is because the regular weigh ins and the moral support of the staff make you less likely to give in to your cat pestering for food. Plus, the staff can often spot areas where you can make a difference or are perhaps slipping up. These weight-watching clinics for your cat may be put on through your veterinarian’s office, or your vet will likely have more info on where to find one in your area. If part of the problem is that you have two cats but only one is overweight, then feed them in separate rooms. This will ensure that each cat only gets the portion of her food that corresponds to her diet.

Summary:
Learn how caloric intake affects weight. Determine the ideal caloric intake for your cat. Consider switching to a prescription weight loss formula cat food. Weigh your cat weekly. Consider taking the cat to a pet weight-watching clinic. Feed your cats separately.