This trial aims to test the feasibility and acceptability of addressing interpersonal barriers to weight-related behavior change. Specifically, the study will test if, by including up to two friends, family members, or co-workers in a lifestyle intervention for weight loss, the person enrolled in the study loses more weight than someone whose friends, family members, or co-workers were not invited to participate.

The investigators will evaluate whether the ROBUST intervention not only addresses individual-level behaviors (i.e., healthy eating, increased physical activity) but also:

1. reduces social undermining as well as changes perceived health norms by activating communal coping - a behavioral process that involves thinking, communicating, and acting as if a health risk (i.e., Type 2 diabetes) is shared; and
2. dampens the harmful effects of increased interpersonal conflict on weight by teaching participants how to induce a positive affect and self-affirming mindset

Participants in the control arm will receive the same number of lifestyle sessions as those randomized to the social network intervention.

Participants will:

1. Be randomly assigned to either the study group, which is asked to invite up to two friends or family members to join them at three coaching sessions, or the group that does not invite anyone.
2. Receive 15 coaching sessions over 24 weeks.
3. Complete an online questionnaire about eating and physical activity habits, confidence in developing healthier habits, mood, and health habits of twelve of their closest friends and family members.
4. Complete a 3-day weekly food log and wear a provided Fitbit for at least 9 hours daily.
5. The invited friends and family members will also be asked to complete a brief questionnaire about their eating and physical activity habits when they start and end the study.

Inclusion Criteria:

• Index Participant:

  1. Black race or Hispanic ethnicity
  2. Male or Female 18 years of age or older
  3. Calculated BMI > 30kg/m2 from objectively measured height and weight by study staff
  4. Access & willingness to use program food intake app via home computer or a smartphone
  5. Ability to identify at least one adult social network member who will participate in the study

• Social Network Member:

  1. Male or Female 18 years of age or older
  2. Access to the internet or a smartphone

Exclusion Criteria:

• Index Participant:

  1. Active enrollment in a weight-loss program, use of weight-loss medications, or planning weight-loss surgery
  2. Advanced medical illness, dementia, hospitalization, injury, or pregnancy that inhibits regular physical activity
  3. Contraindications to exercise based on the Physical Activity Readiness Questionnaire or lack of clearance from a health care provider
  4. Unresolved Food insecurity
  5. Speaks a language other than English or Spanish

• Social Network Member:

  1. Speaks a language other than English or Spanish

Individual participant data that underlie the results reported in any publication will be shared after deidentification (text, tables, figures, and appendices).

Data will become available beginning 6 months following publication and ending 5 years following publication.

Anyone who wishes to access the data can request access for any purpose. Data will be made available and stored indefinitely in the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Central Repository.