Plant-based meat analogs (PBMAs) have attracted much attention due to concerns over theenvironmental issues and disease risks caused by excessive animal meat consumption. High-moistureextrusion processing (HMEP) can be performed to impart plant proteins with a meat-like fibroustexture. However, the knowledge of the physiochemical behaviors of raw materials during HMEPwas still insufficient to understand the formation of structures and textures. Moreover, the lack ofinformation on the nutritional and health impacts of PBMAs has limited consumers’ acceptance. Thiswork aimed to understand the texture mechanism of PBMA using HMEP, where plant proteins wereprocessed with/without oil. Protein structural changes and product properties were characterized, withan exploration into the health and nutrition aspects of HMEP-generated PBMA.Soy protein isolate (SPI) and pea protein isolate (PPI) were selected to comprehensively understandthe texturization and product quality at various barrel temperatures during HMEP. Higher barreltemperatures (120 °C-160 °C) promoted fiber formation in SPI and PPI extrudates. Under the sameHMEP conditions, PPI extrudates produced more fiber and were closer to the hardness and chewinessof cooked chicken breast than their SPI counterparts. Non-covalent interactions played dominant rolescompared to disulfide bonds in stabilizing protein structure in extruded SPI and PPI.Oil addition beyond a critical amount would hinder fiber formation and cause undesirable productquality. For SPI and wheat gluten blend-based extrudates, adding oil in the form of oil-in-water (O/W)emulsion during HMEP was proved to double the maximum oil content compared to direct oiladdition. Oil was distributed as tiny droplets and entrapped inside the protein network in O/Wemulsion-containing extrudates. The structural properties of extrudates showed that oil addition wasbeneficial to lessen the rubber-like texture, promoting the chewiness of extrudates to mimic thecooked chicken breast. Furthermore, increasing oil/water (w/w) ratios in the SPI extrudatescontributed to enhanced protein aggregation, and the protein secondary structure shifted from β-sheetto random coil structure, which was associated with improved protein digestion according to an invitro gastrointestinal investigation.From a health perspective, high-fat dietary SPI-based meat analog fed to male C57BL/6J mice for 10weeks reduced obesity development compared to its animal meat product counterparts (chicken breastand pork loin). This was associated with decreased glucose homeostasis and serum lipid metabolism,lower liver triglyceride level, and reduced hepatic fat accumulation. From a gut shift perspective,compared to high-fat diets involving pork loin, the changes in gut bacterial flora in mice fed withdiets with SPI-based meat analog and chicken breast shifted positively. SPI-based meat analog- andchicken breast-fed groups showed increased relative abundances of anti-obesity bacteriaMuribaculaceae and decreased occurrence of obesity-inducing bacterium Bacteroides and Alistipes.Notably, the peroxisome proliferator-activated receptor α (PPARα) pathway was the mostsignificantly enhanced singling pathway related to lipid metabolism in high-fat dietary SPI-basedmeat analog-fed mice compared to their counterparts. These results indicated that the high-fat dietenriched with SPI-based meat analog alleviated lipid metabolic disturbance compared to animal meat,especially pork loin, which might be associated with the changes in host gut microbial flora and theactivation of the PPARα signaling pathway.Overall, the findings of this thesis highlighted the impacts of plant proteins and oil on the PBMAsquality during HMEP at the macro and micro levels, providing new insights into the texturemechanisms and health impacts of PBMAs using HMEP.