The purpose of this study is to develop and test the feasibility of a behavioral weight loss intervention that uses personalized recommendations for diet and physical activity behaviors in a behavioral weight loss program and to explore factors associated with treatment adherence and response. The 12-week intervention will utilize digital tools for self-monitoring and counseling by weight management professionals. Exploratory analyses will be conducted to determine if there are genetic, metabolomic, microbiome, or psychosocial factors associated with treatment response.

The primary objective of the study is to test a personalized approach for prescribing weight loss strategies in overweight adults participating in a weight loss intervention and to determine if a personalized approach can optimize weight loss compared to a standard behavioral weight loss intervention. Thus, all participants will receive a behavioral weight loss intervention delivered via remote counseling and digital tools including a smart phone app, Wi-Fi- enabled smart scale, physical activity tracker. Participants in the personalized group will also use a continuous blood glucose monitoring (CGM) device.

The differences between the two groups will be the approach used to recommend diet and physical activity changes. The study will compare a Standard Behavioral Weight Loss (BWL) approach tested in numerous previous studies and consistent with current clinical practice, to a Personalized Behavioral Weight Loss (PBWL) approach that tests a combination of diet and physical activity prescriptions to determine the best "fit" for the participant. The PWBL group will actively use CGM information during the intervention period to inform diet and activity behaviors. Participants will be randomized in a 3:1 ratio to PBWL or BWL (i.e., 30 to PBWL and 10 to BWL).

1. Behavioral Weight Loss: The BWL group will receive a standard weight loss intervention based on the evidence-based interventions currently being recommended for clinical practice, with general recommendations for caloric reductions based on starting weight and aimed at achieving a 1-2 lb. average weekly weight loss, and progressive weekly increases of physical activity. Supporting behavioral lessons adapted from materials used in the Diabetes Prevention Program, a landmark behavioral weight loss intervention, will also be delivered. The weight loss 'prescription' will remain consistent throughout the 3 month trial.
2. Personalized Behavioral Weight Loss: The PBWL group will receive a weight loss intervention that is personalized for diet and physical activity recommendations based on a testing period where various approaches to eating and physical activity that may result in differential adherence and response are tested. Calorie recommendations will be based on measured resting energy expenditure and expected activity levels and aimed at achieving a 1-2 lb. average weekly weight loss. In the initial weeks, participants will test various diet and physical activity prescriptions. Following this period, the optimal combination will be identified by the participant, in consultation with their interventionist, based on measured blood glucose, weight loss, hunger and ability to adhere to the prescription. Diet composition (percentage of calories from fat, carbohydrates, and protein) will be personalized along with meal frequency and physical activity goals. This group will receive the same supporting behavioral lessons as the BWL group along with additional resources specific to their personalized prescription. The weight loss 'prescription' will vary across the 3-month trial based on response to treatment.

Inclusion Criteria:

• BMI 25-50 kg/m^2
• Normal or impaired glucose as determined by HbA1c fingerstick (<6.5%)
• Own an iPhone with a data and text messaging plan
• Have home Wi-Fi access
• Have the ability to read, write, and speak English
• Not meeting the American College of Sports Medicine recommendation of 150 minutes of Moderate to Vigorous Physical Activity each week
• Ability to attend 2 in-person assessment visits at the University of North Carolina (UNC) Weight Research Program clinic (at baseline and follow-up) and participate in 12 weekly remote visits with a study interventionist via phone or video call over the 12 week intervention
• Can obtain primary care provider consent that participation is appropriate if needed

Exclusion Criteria:

• Lost more than 10 pounds in the last 6 months and kept it off
• History of weight loss surgery
• Currently participating in another physical activity or weight loss program or research study that may interfere with participation in this study
• Currently meeting exercise recommendations of 150 minutes per week of moderate-to-vigorous physical activity
• Currently pregnant, pregnant within the past 6 months, or planning to become pregnant within the next 4 months
• Planning to relocate in the next 4 months
• Cannot attend 2 in-person assessment visits at the UNC Weight Research Program clinic (at baseline and follow-up) and participate in 12 weekly remote visits with a study interventionist via phone or video call over the 12 week intervention
• Pre-existing medical condition(s) that preclude adherence to an unsupervised exercise program, as determined by items endorsed on the Physical Activity Readiness Questionnaire (PAR-Q)
• Diagnosis of diabetes
• Taking medications to treat prediabetes
• Report taking prescription or over the counter medication with a known impact on metabolism or weight
• Current treatment for cancer
• History of clinically diagnosed eating disorder
• Diagnosis of schizophrenia or bipolar disorder
• Hospitalization for a psychiatric diagnosis within the last year
• Report a past diagnosis of or current symptoms of alcohol or substance dependence
• Unwilling or unable to wear the CGM device continuously for the duration of the study
• On dialysis