Critical Reviews in Food Science and Nutrition, 52:172–182 (2012) Copyright C  Taylor and Francis Group, LLC ISSN: 1040-8398 print / 1549-7852 online DOI: 10.1080/10408398.2010.499763 Nutritional Modulation of Insulin Resistance in the True Carnivorous Cat: A Review ADRONIE VERBRUGGHE, 1 MYRIAM HESTA, 1 SYLVIE DAMINET, 2 and GEERT P.J. JANSSENS 1 1 Laboratory of Animal Nutrition, Faculty of Veterinary Medicine, Ghent University, Heidestraat 19, B-9820, Merelbeke, Belgium 2 Department of Small Animal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133,B-9820, Merelbeke, Belgium Cats are strict carnivores that rely on nutrients in animal tissues to meet their specific and unique nutritional requirements. In their natural habitat, cats consume prey high in protein with moderate amounts of fat and minimal carbohydrates in contrast to commercial diets, which are sometimes moderate to high in carbohydrates. This change in diet has been accompanied by a shift from an outdoor environment to an indoor lifestyle and decreased physical activity, because cats no longer need to hunt to obtain food. This transformation of the lifestyle of cats is thought to be responsible for the recent increase in incidence of obesity, insulin resistance, and diabetes mellitus in domestic cats. At first, an overview of the evolutionary physiological adaptations of carbohydrate digestion in the feline digestive tract and of the hepatic carbohydrate and protein metabolism reflecting the true carnivorous nature of cats is given. Secondly, this literature review deals with nutritional modulation of insulin sensitivity, focusing on dietary macronutrients, carbohydrate sources, and dietary fiber for prevention and treatment of insulin resistance. Keywords Carnivore, cat, insulin resistance, nutrition INTRODUCTION Domestication and urbanization of feral cats have led to a considerable transformation of the cat’s lifestyle. Shift from an outdoor environment to an indoor setting occurred, accom- panied by decreased physical activity, because cats no longer need to hunt to obtain food. Also the cat’s diet changed from low carbohydrate (LC), high protein (HP), prey typical for feral cats (e.g., domestic mouse: 55.8% crude protein, 23.6% crude fat, 8.8% nitrogen free extract and 11.8% ash on dry matter basis (Dierenfeld et al., 2002)) to a high carbohydrate (HC) commercial diet. These changes are held responsible for the recent increase in incidence of obesity, obesity-induced insulin resistance, and type II diabetes mellitus in domestic cats (Rand Address correspondence to Adronie Verbrugghe, Laboratory of Animal Nutrition, Faculty of Veterinary Medicine, Ghent University, Heidestraat 19, B-9820, Merelbeke, Belgium. Tel.: +32 9 264 78 22; Fax: +32 9 264 78 48. E-mail: Adronie.Verbrugghe@UGent.be et al., 2004; Slingerland et al., 2009). Causes and consequences of insulin resistance in domestic cats are shown in Fig. 1. Nowadays, obesity is recognized as the most common nu- tritional disorder in cats, as the prevalence has been increased dramatically during the past decades. In 1973, a study in British veterinary practices found that 6 to 12.5% of 429 cats were over- weight (Anderson, 1973), whereas, twenty years later, Danish investigators found about 40% of 223 cats to be overweight or obese (Sloth, 1992). Also 29% of the 2000 cats presented to private veterinary hospitals in the North-Eastern United States, were overweight or obese using a 6-point body condition scoring system (BCS 5/6 and BCS 6/6, respectively) (Scarlett et al., 1994). In private United States veterinary practices, 28.7% of adult cats were observed to be overweight and 6.4% were found to be obese, using a 5-point body condition scoring sys- tem (BCS 3.5/5 to 4.5/5 and BCS 4.5/5 to 5/5, respectively). A total of 35% of more than 8000 adult cats were either overweight or obese (Lund et al., 2005). Moreover, Prahl et al. (2007) re- ported an increased incidence of feline diabetes mellitus over 172 Downloaded by [University of Guelph] at 05:57 05 December 2011