Restricted feeding of weight control diets induces weight loss and affects body composition, voluntary physical activity, blood metabolites, hormones, and oxidative stress markers, and fecal metabolites and microbiota of obese cats.

Feline obesity puts many cats at risk for comorbidities such as hepatic lipidosis, diabetes mellitus, urinary tract diseases, and others. Restricted feeding of specially formulated diets may improve feline health and safely support weight loss while maintaining lean mass. The objective of this study was to determine the effects of restricted intake of weight control diets on weight loss, body composition, voluntary physical activity, serum metabolic and inflammatory markers, and fecal metabolites and microbiota of obese cats. Twenty-four obese adult domestic shorthair cats [body weight (BW) = 5.51 ± 0.92 kg; body condition score (BCS) = 8.44 ± 0.53] were used. A leading grocery brand diet was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (week 0), cats were allotted to one of 2 weight control diets (DRY or CAN) and fed to lose 1.5% BW per week for 18 wk. At baseline and 6, 12, 18 wk after weight loss, dual-energy x-ray absorptiometry scans were performed, blood and fecal samples were collected, and voluntary physical activity was measured. Change from baseline data was analyzed statistically using the Mixed Models procedure of SAS, with P < 0.05 being significant and P < 0.10 being trends. BW was reduced by 1.54 ± 0.51% per week. Restricted feeding of both diets led to BW (P < 0.01) and fat mass loss (P < 0.01), reduced BCS (P < 0.01), reduced leptin (P < 0.01) and insulin (P < 0.01) concentrations, and increased superoxide dismutase (P < 0.01) and active ghrelin (P < 0.01) concentrations. Change from baseline fecal scores was reduced (P < 0.01) with restricted feeding and weight loss, while total short-chain fatty acid, acetate, and propionate concentration reductions were greater (P < 0.05) in cats fed CAN than those fed DRY. Fecal bacterial alpha diversity measures increased (P < 0.01) with restricted feeding and weight loss. Fecal bacterial beta diversity was altered by time in all cats, with week 0 being different (P < 0.05) than weeks 6, 12, and 18. Change from baseline relative abundances of 3 fecal bacterial phyla and over 30 fecal bacterial genera were impacted (P < 0.05) or tended to be impacted (P < 0.10) by dietary treatment. Our data demonstrate that restricted feeding of both weight control diets was an effective means for weight loss in obese adult domestic cats. Some changes were also impacted by diet, highlighting the importance of diet formulation and format, and nutrient composition in weight control diets.