Piloting a Generative Artificial Intelligence Chatbot in a Mobile Weight Loss Program

Inclusion Criteria: * body mass index (BMI) of 25-45 kg/m\^2 * English-speaking and writing * own an iPhone with a data plan * willing to be randomized to either treatment group Exclusion Criteria: * Type 1 diabetes or currently receiving medical treatment for Type 2 diabetes * Other health problems which may influence the ability to walk for physical activity or be associated with unintentional weight change, including tuberculosis, currently receiving cancer treatment, or history of a heart attack or stroke * Report a heart condition, chest pain during periods of activity or rest, or loss of consciousness on the Physical Activity Readiness Questionnaire (PAR-Q; items 1-4), or report any other reason not able to walk for physical activity * Lost 10 or more pounds (and kept it off) in the last 6 months * Currently taking weight loss medications * History of weight loss surgery or planning weight loss surgery in the next 4 months * Report a past diagnosis of, or receiving treatment for, a DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision) eating disorder (anorexia nervosa or bulimia nervosa) * Currently pregnant or planning to become pregnant within the next 4 months * Health or psychological diagnoses that preclude participation in a prescribed dietary and exercise program, including history of or diagnosis of schizophrenia or bipolar disorder, hospitalization for a psychiatric diagnosis in the past year, current diagnosis of alc…