Subcutaneous adipose tissue (scAT) and peripheral blood mononuclear cells (PBMCs) play a significant role in obesity-associated systemic low-grade inflammation. High-fat diet (HFD) is known to induce inflammatory changes in both scAT and PBMCs. However, the time course of the effect of HFD on these systems is still unknown. The aim of the current study was to determine the time course of the effect of high fat diet (HFD) on PBMCs and scAT. New Zealand white rabbits were fed HFD for 5 or 10 weeks (i.e., HFD-5 and HFD-10), or regular chow (i.e., CNT-5 and CNT-10). Thereafter, metabolic and inflammatory parameters of PBMCs and scAT were quantitated. HFD induced hyperfattyacidemia in HFD-5 and HFD-10 groups, with the development of insulin resistance (IR) in HFD-10, while no changes were observed in scAT lipid metabolism and inflammatory status. HFD activated the inflammatory pathways in PBMCs of HFD-5 group, and induced modified autophagy in that of HFD-10. The rate of fat oxidation in PBMCs was directly associated with the expression of inflammatory markers; and tended to inversely associate with autophagosome formation markers in PBMCs. HFD affected systemic substrate metabolism, and the metabolic, inflammatory, and autophagy pathways in PBMCs in the absence of metabolic and inflammatory changes in scAT. Dietary approaches or interventions to avert HFD-induced changes in PBMCs could be essential in prevention of metabolic and inflammatory complications of obesity, and promote healthier living.