"Dog and cat owners buying weight-control diets for their overweight pets are faced with a confusing two-fold variation in calorie density, recommended intake, and wide range cost of low-calorie pet foods, according to a study by the Cummings School of Veterinary Medicine at Tufts University."
"...Among their findings is that dry dog foods range in calorie density from 217 to 440 kilocalories per cup (kcal/cup) and a recommended intake that ranged from 0.73 to 1.47 times the dog's resting energy requirement. The diets also varied wildly in price - from 4 cents to more than $1.10 per kilocalorie."
"Similar findings were made in wet dog food (189-398 kcal/can) and cat food (235-480 kcal/cup) marketed for weight control."
"...Another important issue identified in this study was the high variability in feeding recommendations for weight loss based on the labels that were evaluated. In fact, for most of the diets, pets would not lose weight or would actually gain weight if owners adhered to the labels' feeding directions and did not adjust according to their pet's individual calorie requirements."
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Aksum Notes: The average adult cat needs 20 to 30 calories per pound of body weight every day.
A 5 lb. lean adult domestic cat needs 150-170 calories and a 10 lb cat needs about 200-280 calories. Add about 25 calories per lb to calculate correct calorie needs. For example, an 8 lb cat needs 210-240 calories per day. Adjust up if your cat is very active, and adjust down if your cat is not active.
Enough protein is very important for a cat. With too much carbohydrates in their food, cats are susceptible to diabetes. A 10-pound cat should have about 12.5 grams (approximately 90 calories) of protein and 5.5 grams (about 70 calories) of fat each day. Grains provide "empty calories" for cats, the same way doughnuts and other snack foods do for humans.
Pregnant/nursing cats and kittens need much more calories than adult cats (a 10 lb nursing cat needs about 600 calories). Allow them to eat what they want (free feed).
Measure out the amount of food for adult cats each feeding (Taste of the Wild dry cat food has 390 calories per cup), and feed them when you are there. Feed twice a day or more often. Take up the food after 10-30 minutes.
Tips: Change from dry food to wet food. Limit treats or give no treats. Add canned pumpkin to the food to add fiber intake. Increase exercise. It's fun to play with your cat!
Sources:
The One Best Thing For Your Cat's Health
Your Cat's Nutritional Needs
Adult Cats - Caloric & Nutrition Requirements
Daily Caloric Intake For Cats
Taste of the Wild Rocky Mountain Feline Formula
Feeding Your Cat: Know The Basics Of Feline Nutrition