Black Girls Move is a school-linked daughter/mother physical activity and dietary behavior program, with 9th and 10th grade students. This program is designed to prevent obesity in Black adolescent females and thus aligns with the NIH mission to enhance health, lengthen life, and reduce illness and disability. This project is relevant to public health because it holds the potential to reduce population health disparities impacted by structural racism.

Black female adolescents are at increased risk for obesity-related morbidity and mortality as adults compared to non-Hispanic White female adolescents. Interventions to prevent obesity in Black female adolescents that leverage the relationship of the daughter/mother dyad have received limited attention. Studies that do include mothers tend to use theoretical frameworks that do not explicitly build on this important family relationship and have not included mothers' active participation. Additionally, these studies do not include girls over the age of 12. In response, the investigators developed Black Girls Move, a school-based obesity prevention intervention that addresses these limitations in the extant literature. The investigators conducted focus groups with daughter/mother dyads to identify practical, cultural, and age-appropriate strategies for improving physical activity (PA) and dietary behaviors in Black adolescent daughters (grades 9-10, ages 14-17). Black Girls Move consists of 12 weekly group sessions of daughter/mother dyads in which participants set individualized PA and dietary goals. Black Girls Move incorporates content and processes derived from asset-based anti-racist Public Health Critical Race Praxis, Family Systems Theory, and Social Cognitive Theory. Specific aims are to determine the efficacy of Black Girls Move compared to daughters-only comparison condition on change in PA and dietary intake, and the impact of Black Girls Move compared to daughters-only on theoretical mechanisms of change (racial identity, daughter/mother relationship, social cognitions) assessed by self-report measures.

The design is a 12-week pre-test/post-test, randomized controlled trial. The investigators will recruit 24 daughter/mother dyads at each of 8 schools for a total sample size of 192 daughter/mother dyads (total 384 participants). Within school, each dyad will be randomized to either Black Girls Move or daughters-only comparison condition (12 per condition). All daughters and all mothers (Black Girls Move daughter/mother dyads and daughters-only comparison condition daughter/mother dyads) complete assessments (e.g., PA, diet, family measures) at baseline, post-intervention, and 3-months post-intervention. The investigators recognize that there are potential validity threats associated with within school student randomization. The investigators will collect data to assess the degree to which these potential threats are pertinent. The long-term goal of this research is to decrease disparities in obesity and associated comorbidities in Black women. The findings may inform future large scale R01 studies of BGM in Black daughter/mother dyads

Inclusion Criteria for daughters are:

• English speaking;
• Black;
• grade 9 or 10;
• daily access to the internet outside of school and/or work through an iOS or android smart phone, tablet, or personal computer;
• either high-normal weight (between ≥50th and <85th percentile for age and gender) or overweight (between ≥85th and <95th percentile for age and gender) as the purpose of this study is weight maintenance and obesity prevention in at-risk daughters rather than obesity treatment; 98 and
• have either a poor diet, (defined as consuming <1 vegetable or <1 fruit per day) 99 or inadequate PA (defined as < 60 minutes per day, 7 days per week). 99,100

Inclusion criteria for mothers are:

• English-speaking;
• Black;
• co-residing biological mother or mother-figure and legal guardian of the participating daughter;
• the person primarily responsible for meals in the household; and
• access to the internet through an iOS or android smart phone, tablet or personal computer. In a longitudinal study of 480 adults, 84% of adults with obesity were adolescents with high normal weight status (≥50th and <85th percentile). National data on cell phone ownership show that 81% of Black students and 68% of Black parents own a smart phone

Exclusion Criteria:

The exclusion criteria for both daughters and mothers includes:

• having conditions/procedures that prevent the oral consumption of foods (e.g., gastric feeding tubes);
• presence of physical limitations that would preclude participation in the PA activity components of the intervention;
• altered dietary intake (e.g., pregnancy, eating or metabolic disorders except for type 1 or type 2 diabetes); and
• at baseline physical assessment, participants screened for uncontrolled blood pressure (systolic > 130, diastolic >80 for daughters; and systolic >160, diastolic >100 for mothers) will be eligible only with a healthcare provider release.
• participants with diagnosed type 1 or 2 diabetes will be eligible for participation only with a healthcare provider release.
• mothers will be screened for cardiovascular disease and musculoskeletal risk factors with the 7-item Physical Activity Readiness Questionnaire. Mothers that answer 'yes' to any item on the Physical Activity Readiness Questionnaire will be eligible only with a healthcare provider release. Daughters or mothers who are asked to provide healthcare provider release will be referred to the Chicago Department of Public Health if they do not have a primary care provider. To be eligible to participate in either condition, both the daughter and her mother must be willing and eligible to participate in the study.