The present disclosure relates to methods for treating or preventing obesity and/or nonalcoholic fatty liver diseases (NAFLDs) and/or nonalcoholic steatohepatitis (NASH) using a glucagon receptor blocking agent. In various embodiments, the present disclosure relates to methods for treating or preventing NAFLD/NASH using antigen binding and antagonizing proteins, e.g., fully human antibodies, that specifically bind to and antagonize the function of the human glucagon receptor.