Start with Calories – For feline weight loss, the formulas seem simple enough: fewer calories in plus more calories out equals weight loss. Unfortunately, it’s not as simple as that formula makes it appear. For starters, cats that are overweight or obese must eat. Their physiology is different than humans or dogs and if they do not eat for as little as two consecutive days, they can develop a life-threatening form of liver disease known as hepatic lipidosis. Obese humans starting a diet program are also vulnerable to this serious condition. It is for this reason that you should never put your cat on a diet without the assistance of your veterinary healthcare team. Let’s start by calculating the calories your cat needs. You’ll first need to have your cat examined by your veterinarian and an ideal weight calculated. The average domestic cat should weigh approximately eight to ten pounds. If your cat is 18 pounds, you can calculate its ideal weight to be 10 to 12 pounds (your veterinarian will help you with this).

A basic formula for weight loss in cats is:

  • Ideal weight in pounds divided by 2.2 give you weight in kilograms (kg)
  • Calculate the Resting Energy Requirements (RER) based on this ideal weight
    • 70 x
      [(ideal weight in kg)] ¾ or 70 x [(ideal weight in kg) to the ¾ power]
    • or RER in kcal/day = 30(ideal or target body weight in kilograms) + 70
  • For weight loss in cats multiply RER times 0.8