Eatwell Clinical Trial (R01)

Inclusion Criteria: * Age 18 or older * Access to technology necessary to receive emails and join videoconferencing meetings * Ability to read and speak English * Willingness to be randomized to either study condition, including ability and willingness to attend intervention sessions * Ability and willingness to attend intervention sessions, receive monthly email messages, and serve in support role if index participant in household is assigned to Eatwell condition * Able and willing to visit a commercial laboratory partnered with this project (e.g., Labcorp) in order to have their blood drawn at the time of study visits * Low adherence to WCRF/AICR's four dietary guidelines (operationalized as a level of intake, based on brief self-report questions administered during phone screening, that corresponds to a score of 2 or less in the Shams-White method of dietary adherence scoring) * Share a household (i.e., a private residence with a shared living space, including kitchen) with an adult who provides informed consent, meets eligibility criteria, and anticipates remaining in this household for the majority of the next 18 months * Agree that they will not join another intervention study run by this study team in the next 18 months * Successful completion by self and household member of all enrollment and baseline data collection tasks * Have an email that they regularly check and willingness to use that for corresponding to study staff * Weight at baseline of 396 lbs or less, as the digital scales used for measurement are not able to obtain measurements for weights higher than this Exclusion Criteria: * A medical or psychiatric condition, including self-reported history of anorexia nervosa or bulimia nervosa, that may limit appropriateness of or ability to comply with dietary recommendations * A psychiatric condition, including self-reported history of anorexia nervosa or bulimia nervosa, that may make it difficult or inappropriate for household member to serve in support role * Currently taking medication that can substantively change appetite or eating behavior, including using of a GLP-1 medication * Planning to enroll in another lifestyle modification program in the next 18 months * History of bariatric surgery * Currently pregnant or planning to become pregnant in the next 18 months * Type 1 Diabetes