Isoenergetic reduction of dietary macronutrients affects body composition, physical activity, and post-prandial hormone responses in lean and obese cats fed to maintain body weight

Hannah Godfrey¹Érico de Mello Ribeiro¹Shoshana Verton-Shaw¹Anna Katharine Shoveller¹Darcia Kostiuk²Janelle Kelly²Jennifer Saunders Blades²Adronie Verbrugghe^1*

• ¹University of Guelph, Guelph, Canada
• ²Champion Petfoods Holding Inc, Morinville, Canada

High consumption of dietary carbohydrates (nitrogen-free extract, NFE) in extruded dry foods is postulated as a risk factor for feline obesity, though evidence is limited. This study utilized a three-test diet approach to isolate the effect of each macronutrient on body composition, voluntary physical activity, and serum satiety hormone response in lean and obese cats. A pairwise isoenergetic reduction as % metabolizable energy (ME, using modified Atwater) of dietary macronutrients created a low-protein (LP; protein=28%, fat=40%, NFE=32%ME), low-fat (LF; protein=40%, fat=30%, NFE=30%ME), and lowcarbohydrate (LC; protein=36%, fat=41%, NFE=23%ME) diet. Cats (lean n=9; obese n=9) were fed the LP, LF, or LC diet to maintain body weight for 4-weeks in a 3x3 Latin square design. Voluntary physical activity was measured from day 15-21. On day 23, body composition was assessed by dual energy x-ray absorptiometry. On day 24, blood was collected for fasted and 6-h post-prandial serum satiety hormones. Data were analysed using SAS Studio via proc GLIMMIX with significance set at P<0.05. Greater lean soft tissue mass was observed for LF compared to LP and LC (P=0.0101) though no other changes in body composition were observed. Daily food intake (g/d) differed among diets (LP:56.14±0.56;