High starch intake favours body weight control in neutered and spayed cats living in homes fed ad libitum

Abstract

Different starch-to-protein ratios were compared among neutered and spayed domiciled cats. Male and female obese and non-obese cats were fed kibble diets ad libitum for four months high in starch (HS(38%CP): starch 32%, protein 38%; dry-matter basis) or high in protein (HP(55%CP): starch 19%, protein 55%) but similar in energy and fat in a crossover design. Physical activity was evaluated using an accelerometer, and body composition (BC), energy expenditure (EE), and water turnover (WT) using the doubly labelled water method. Results were compared in a 2 diet × 2 sex × 2 body condition factorial arrangement. Cats fed the HS(38%CP) diet maintained a constant bodyweight, but lean mass (LM) tended to be reduced in female obese but to be increased in male non-obese (P<0•08) and increased in female non-obese cats (P=0•01). The HP(55%CP) diet induced an increase in cat bodyweight and LM (P<0•05) without altering BC proportion. EE tended to be higher in males (351 (SE 8) kJ/kg0.67/day) than females (330 (SE 8) kJ/kg0.67/day; P=0•06), was unaffected by diet or BC, decreased as age increased (R 2 0.44; P<0•01), and increased as physical activity increased (R 2 0.58; P<0•01). WT was higher for the HP(55%CP) diet (P<0•01) and increased with EE (R 2 0.65; P<0•01). The HS(38%CP) diet favoured bodyweight control during four months of ad libitum feeding. Caution is necessary to balance protein in diets of female obese cats over five years, as they may have low energy and food intake, with LM loss.