The objective of this study was to evaluate the effect of sex and feed restriction on energy metabolism of 72 Saanen goat kids (24 intact males, 24 castrated males and 24 female) with initial BW of 15.8 ± 0.17 kg. At the beginning of the experiment 6 animals of each sex were slaughtered with 15 kg of BW to estimate their initial body composition. The remaining 18 kids of each sex were assigned to 3 levels of feed restriction (ad libitum, 25% and 50% of feed restriction), with 6 kids per sex-feeding level (3 × 3 factorial). Animal sets (1 kid per sex-feeding level) were slaughtered when BW of ad libitum kids was 30 kg. Blood samples were collected from all animals every 10 d, in a total of 7 blood collections (70 d of experimental period). In these samples, we evaluated glucose, cholesterol, NEFA, β-hydroxybutyrate (B-HB) and aspartate aminotransferase (AST). Data were analyzed using Proc Mixed of SAS. Females presented greater fat deposition (31.6 ± 0.36% EBW) than castrated males (24.7 ± 0.36% EBW) and intact males (11.5 ± 0.36% EBW) regardless the level of feed restriction (P < 0.0001). Serum glucose was similar in intact and castrated males throughout the experiment (67.4 ± 4.59 mg/dL). As the feed restriction level increased, serum AST activity of castrated males decreased (P = 0.0251) in a ratio of 4.3% for those subjected to 25% of feed restriction and 15.8% for those under 50% feed restriction compared with castrated fed ad libitum. In females, AST activity was higher in those subjected to 50% feed restriction (83.83 ± 4.96 U/L), whereas in intact males remained unchanged regardless of the restriction regimen (80.9 ± 4.95 U/L). The highest B-HB concentration was observed when animals were subjected to the maximum level of feed restriction (0.129 mmol/l) followed by those fed ad libitum (0.103 mmol/L) and restricted by 25% (0.090 mmol/L; P < 0.0149). Sex and feed restriction did not influence NEFA and cholesterol blood levels (P > 0.05). Goat kids of different sex act physiologically different when subjected to feed restriction. Females changed all their glycolytic metabolism to keep the fat deposition even when they are subjected to feed restriction.