Currently, there are conflicting data on the benefit of CLA as an anti-obesity agent in humans and cats, with the most recent data suggesting lack of a significant effect. Therefore, more information is needed before it can be recommended.

A major hurdle to conventional weight-loss programs is the fact that energy restriction causes hunger, leading to increased begging and scavenging activity. This puts increased strain on the owner-animal bond, causing owner non-compliance or complete withdrawal from the program.

Therefore, developing strategies to improve satiety would greatly assist in case management. Many human studies show that absorption of macronutrients is lower following consumption of high-protein foods than after consumption of foods with a high carbohydrate or fat content.

Therefore, proteins are sources of glucose that induce little insulin secretion and delay the appearance of hypoglycemia (which contributes to the feeling of hunger).

The satiety effect of proteins is variable, because speed of digestion varies among different proteins, and different amino acids induce the secretion of insulin to varying degrees.

Dietary fiber may increase satiety, due to gastric distension which causes cholecystokinin release and a subsequent slowing of gastric emptying.

Under certain conditions in humans, dietary fiber has been shown to exert a satiety effect, although some studies have failed to detect significant reduction in appetite. There are similar discrepancies in dog studies with some, but not all, suggesting effects on satiety. Apparent inconsistencies are likely the result of differing investigative methods and of the dose and type of fiber used.

In recent studies in colony dogs, three different diets (HPHF, high protein [103g/1000Kcal] high fiber [60g/1000Kcal]; HP, high protein [104g/1000Kcal] moderate fiber [35g/1000Kcal]; HF, moderate protein [86g/1000Kcal] high fiber [87g/1000Kcal]), designed for weight loss were assessed for their satiety effect.

Voluntary food intake was measured in five sequential crossover studies. Palatability was assessed with taste tests.

Short-term (food offered for 15 minutes every hour for four hours) and medium-term (food offered three hours after the first meal) satiety was best for the HPHF diet.

Voluntary food intake at the second meal (fed three hours after a restricted meal of 25 percent of daily metabolic energy requirements) was significantly lower than the first meal for the HPHF diet, but not the HP or HF diets.

The HPHF and HP diets had equivalent palatability, and both were more palatable than the HF diet.

These studies suggest that diets supplemented in both protein and fiber have the greatest satiating effect, and may improve compliance with conventional weight-loss programs.

Lifestyle management

Increasing physical activity is a useful adjunct to dietary therapy during weight management. Studies in humans suggest that increasing activity promotes fat loss, while preserving lean tissue during weight loss. The exact program should be tailored to the individual, and take into account any medical concerns.

Suitable exercise strategies in dogs include lead walking, swimming, hydrotherapy and treadmills.

Exercise in cats can be encouraged by increasing play activity, using cat toys (e.g., fishing-rod toys), motorized units and feeding toys.

Cats can be encouraged to work for their food by moving the food bowl between rooms prior to feeding, or by the use of feeding toys. Activity monitors (accelerometers, pedometers) recently have been validated for dogs, and may help provide a more objective assessment of activity during weight-loss programs in the future.