The potential utilization of microparticulated whey protein (MWP) as a fat mimetic in reduced calorie model sauces and dressings was examined. The influence of solution composition (pH and salt) and processing (homogenization and heating) on the properties of MWP (0–20%) suspensions (0.01 M phosphate buffer, pH 6) was studied. High-pressure homogenization (6000 psi, 1 pass) of MWP suspensions significantly reduced protein particle size and improved their stability to sedimentation. The lightness and viscosity of the suspensions increased with MWP concentration, which was attributed to the influence of the protein particles on light scattering and fluid flow. Thermal treatment (90 °C for 5 min) of MWP suspensions increased their viscosity, which was associated with increased protein aggregation. Solution pH (2–8) also had an impact on the particle size and microstructure of the MWP suspensions, which was attributed to changes in particle charge: the charge went from negative to positive with decreasing pH, with an isoelectric point around pH 4.5. Addition of calcium chloride (10 mM) to heated systems did not cause significant changes in suspension rheology, which was attributed to pre-denaturation of the MWP. Overall, this study highlights conditions where MWP can be used as potential fat replacers in low calorie food emulsions. MWP increases the lightness and viscosity of products, thereby mimicking some of the desirable characteristics of fat droplets.