According to the CDC, over one-third of adults in the United States are obese. Long-term obesity has been linked to many health problems including heart disease, diabetes, and several forms of cancer. Unlike humans that tend to gain weight as we age, there are vertebrates that appear to be resistant to weight increase such as many species of non-migratory birds including zebra finches. The goal of this experiment was to determine if we could alter weight in zebra finches by exposing them to a high caloric diet of finch seed mixed with suet (15% by weight). We hypothesized that birds receiving suet would gain more weight compared to controls. Birds were fed either regular finch seed or suet mixed diet for 17 weeks, and were housed in modified cages to restrict activity. Every other week they were weighed, and lean mass and fat mass were measured using an EchoMRI. From this, average lean and average fat mass percentages were calculated. Preliminary results demonstrate that within the suet fed group there was variability in these two measures that paralleled controls. Despite this, neither group experienced a significant change in weight. These results imply that there is a mechanism responsible for maintaining weight homeostasis that cannot be overridden by solely challenging them with an increased calorie diet. Some possible mechanisms that may explain the results include increased metabolism, an increased output of thermoenergy, or changes in food consumption.