Energy restriction results in a mass-adjusted decrease in energy expenditure in cats that is maintained after weight regain.

Dietary energy restriction (ER) is used to treat obesity in cats but it is often unsuccessful. The purpose of this study was to determine whether ER results in a sustained decrease in mass-adjusted energy expenditure (EE) that may oppose weight loss and promote weight regain. EE and body composition were measured in 10 adult neutered cats at 3 time points: baseline (obese cats), during weight loss (40% ER), and following weight regain. The cats started with a body weight (BW) of 6.1 +/- 0.30 kg, body condition score (BCS) of 7.6 +/- 0.14 (on a 9-point scale), and fat body mass (FM) of 38 +/- 1.0% of BW. After weight loss, BW was 5.0 +/- 0.19 kg, BCS was 5.5 +/- 0.07 kg, and FM was 31 +/- 1.6% (P < 0.01). After weight regain, BW was 6.2 +/- 0.30 kg, BCS was 7.7 +/- 0.16, and FM was 42 +/- 1.8% (P < 0.01). Total EE decreased from 1258 +/- 33.7 kJ/d to 1025 +/- 39.6 kJ/d during weight loss (P < 0.001). After weight regain, EE was still lower than baseline (1103 +/- 41.5 kJ/d, P < 0.001). Energy intake (EI) at baseline (1337 +/- 50.6 kJ/d) was higher than EI after weight loss and regain (1217 +/- 61.2 kJ/d), resulting in no differences in energy balance (78 +/- 30.4 and 104 +/- 35.4 kJ/d, respectively, P = 0.581). These results support the hypothesis that ER results in a mass-adjusted decrease in EE in cats that is maintained after weight regain.