When choosing a weight-control or low-calorie pet food, pet owners are faced with a large number of products and product types. Understanding what products are best for your dog or cat can be confusing. Evaluating product calorie and nutrient content, as well as pricing, are important in choosing the correct diet.
One challenge is that the weight-control diets available represent a wide range of calorie concentrations and recommended calorie intakes for dog and cat weight-control diets. For example, one published report found that dry dog food marketed for weight control ranged from 217 to 440 kilocalories per cup of food. Combined with the feeding recommendations, the food provided between 0.73 to 1.47 times a dog’s resting energy expenditure (Linder and Freeman, 2010). Similar ranges were noted for canned dog and cat foods for weight control also.
A recent survey released by the Association for Pet Obesity Prevention (2011) found that 51 percent of dogs are overweight or obese. Obesity is the most common nutritional problem among dogs and cats. Poor feeding habits, such as feeding table scraps or too much food, and a lack of physical activity greatly contribute to the development of canine obesity. Animals that are obese are at a higher risk of developing health disorders including cardiac disease, diabetes, respiratory problems, arthritis, increased risk of injury, and complications during surgery. Obesity in pets should be treated with a combination of change in diet and activity level of the animal.
AAFCO guidelines for weight-control diets: The Association of American Feed Control Officials (AAFCO) has established definitions to categorize pet foods according to their calorie and fat content. These definitions are applicable to both dog and cat foods. Pet foods labeled as light, lite, or low-calorie must list calorie concentration in kilocalories per cup on the label. Soon, all pet foods will provide calorie content on the label to make comparisons easier.
AAFCO guidelines for weight-control dog and cat foods provide specific requirements in terms of the amount of calories and fat that may be included in the food. Different guidelines apply for dry vs. canned or moist foods. Dry pet foods are defined as those that contain less than 20percent water, whereas moist pet foods are those with greater than 65 percent moisture.
For a dry dog food to be called light, lite, or low-calorie, it must have less than 3,100 kilocalories metabolizable energy per kg of food on an as is basis. Light, lite, or low-calorie moist dog foods must contain less than 900 kilocalories metabolizable energy per kg. In contrast, a dry dog food may be termed lean or low-fat if it is less than 9 percent fat on an as is basis (or as it is listed on the label) and a moist dog food can apply these terms if it is less than 4 percent fat.
For dry cat foods, the terms light, lite, or low-calorie describe foods with less than 3,250 kilocalories metabolizable energy per kg of food. For moist cat foods, these terms mean a diet will have less than 950 kilocalories metabolizable energy per kg. The terms lean or low-fat may be used to describe dry cat foods that contain less than 10% fat or moist cat foods with less than 5 percent fat.
Feeding guidelines: In addition to calorie content of the diet, owners should pay close attention to feeding guidelines to calculate the calorie intake per day for their pets. Owners should compare the feeding recommendations to the actual calorie requirements of the animal. Having the calorie content of the diet on the label will make it easier for owners to compare diets and determine optimal feed intake. Calorie intake for less active dogs can be calculated using the following equation: kcal/d = 95 x kg0.75. For example, a 40-pound dog would require approximately 836 kilocalories per day [95 x (40/2.2)0.75].
Calorie intake for a cat can be calculated using one of two equations depending on the cat’s body condition score. Cats that are overweight (BCS > 5) have an energy requirement based on the following equation: kcal/d = 130 x kg0.4. A 12-pound overweight cat would require approximately 256 kilocalories per day [130 x (12/2.2)0.4]. While a 12-pound cat at an ideal weight, it would require 312 kilocalories per day.
The feeding guidelines provided on the pet food label are a good starting point for determining how much food your pet should be fed each day. There are, however, large variations in these guidelines. You need to monitor your pet’s body condition score and overall weight and adjust food offered based on changes in weight. Many animals may need to be offered less food than recommended on the label to lose weight. The ideal rate of weight loss is no more than 1 to 2 percent of total body weight each week. More rapid weight loss can result in the animal gaining the weight back if the weight reduction program ends and can result in hepatic lipidosis (a severe liver disease) in cats.
Paying attention to the amount and type of food offered is the first step toward successful weight loss in dogs and cats. In addition, exercise levels in these animals should be increased to promote weight loss and increase muscle mass. Animals at an ideal body weight have fewer health problems and longer life spans than those that are overweight.
Lisa Karr-Lilienthal, Ph.D. – University of Nebraska-Lincoln