• Percent weight loss: objective [ Time Frame: Baseline, 6 Months ]
  Weight change from baseline to 6 months calculated as a percent from baseline weight.
• Weight [ Time Frame: Baseline, 6 Months ]
  Absolute weight change from baseline to 6 months.

• Dietary tracking adherence [ Time Frame: from Baseline to 6 Months ]
  Number of days of complete dietary tracking summed over the 6-month study period.
• Parent diet [ Time Frame: Baseline, 6 Months ]
  Change in parent daily caloric intake as measured by 24-hour dietary recall from baseline to 6 months.
• Child diet [ Time Frame: Baseline, 6 Months ]
  Change in child daily caloric intake as measured by 24-hour dietary recall from baseline to 6 months.
• Percent weight loss: WiFi scale [ Time Frame: Baseline, 3 Months, 6 Months ]
  Weight change calculated as a percent from baseline weight (measured in kg), using official assessment weights taken from participants' study-provided WiFi-enabled weighing scale and transmitted via WiFi, from baseline to 3, and 6 months.
• Child BMI-percentile [ Time Frame: Baseline, 6 Months ]
  Change in child BMI-percentile using at-home measurements of child's weight (on parent WiFi-enabled scale) and height

• Dietary tracking adherence [ Time Frame: from Baseline to 6 Months ]
  Number of days of complete dietary tracking summed over the 6-month study. period
• Parent diet [ Time Frame: Baseline, 6 Months ]
  Change in parent daily caloric intake as measured by 24-hour dietary recall from baseline to 6 months.
• Child diet [ Time Frame: Baseline, 6 Months ]
  Change in child daily caloric intake as measured by 24-hour dietary recall
• Percent weight loss: WiFi scale [ Time Frame: Baseline, 3 Months, 6 Months ]
  Weight change calculated as a percent from baseline weight, using official assessment weights taken from participants' study-provided WiFi-enabled scale, from baseline to 3, and 6 months.
• Child BMI-percentile [ Time Frame: Baseline, 6 Months ]
  Change in child BMI-percentile using at-home measurements of child's weight (on parent WiFi-enabled scale) and height

• Minutes of moderate-to-vigorous physical activity [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in minutes of moderate-to-vigorous physical activity as measured by the Paffenbarger Physical Activity Questionnaire, from baseline to 3, and 6 months. The PPAQ is a self-administered questionnaire that asks for a recall of physical activity over the previous 1 week. Participants report how many days and for how many minutes each day they engage in brisk walking, and report other exercise activities that week (non-occupational and non-household-related), including how many days and for how many minutes each time. Activities are assigned MET values according to the Compendium of Physical Activities, when are then used to classify activities as light moderate, or vigorous, and are also assigned energy expenditure amounts in kcal. These values are used to calculate total energy expenditure in kcal/week, as well as energy expenditure from and total minutes engaged in moderate-to-vigorous activities, measured in kcal/week and minutes/week, respectively.
• Sedentary behavior [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in sedentary behavior as measured by the self-administered Sedentary Behavior Questionnaire for Adults (SBQ), from baseline to 3, and 6 months. The SBQ asks about amount of sitting time on weekdays (8 items) and weekends (8 items), and are scored by summing up the total time spent in sedentary time (in hours) on weekdays and weekends, ranging from 0 hours to 6+ hours per day.
• Physical food environment [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in healthy and unhealthy foods offered in the home as measured by a physical food environment self-report questionnaire, from baseline to 3, and 6 months. There are 80 total items, 32 unhealthy items and 48 healthy items. Participants report whether each food/drink item is in the home or not (yes or no), and the items are summed for an unhealthy total and healthy total, and may also be used to total number of sugar-sweetened beverages/juice (out of 8 items), caloric beverages (15 items), fruits (17 items), vegetables (14 items), high-fat high-calorie items (20 items), and low-fat low-calorie items (14 items). Higher numbers indicate greater amounts of those types of food in the home.
• Social food environment [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in social food environment as measured by the Meals in our Household Questionnaire, from baseline to 3, and 6 months. This consists of 50 items across 6 subscales, summed to create a total score for each: structure of family meals (10 items, score range 0-40), problematic child mealtime behaviors (20 items, range 0-70), use of food as a reward (6 items, range 0-24), parental concern about child's diet (17 items, range 0-85), spousal stress related to child's mealtime behaviors (4 items, score range 4-20), and influence of child's food preferences on what other family members eat (3 items, range 2-14). Higher scores indicate higher instances of use of the scale in question (ex: greater structure of family meals, greater use of food as a reward, etc.).
• Household food rules [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in household food rules as measured by 12 items from the self-report Active Where Parent-Child Survey, from baseline to 3, and 6 months. The 12 items are summed to create a total score that ranges from 0-12, where higher scores indicate a greater number of food rules used.
• Weight control self-efficacy [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in weight control self-efficacy using the 20-item self-report Weight Efficacy Lifestyle Questionnaire, from baseline to 3, and 6 months. Items are rated on a scale of 0-9, and summed for a total score ranging from 0-180, with higher scores indicated greater self-efficacy.
• Self-efficacy for exercise [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in self-efficacy for exercise, as measured by the self-reported Self-Efficacy and Exercise Habits Survey, from baseline to 3, and 6 months. Responses for two subscales (Sticking to it - 8 items, Making time for exercise - 4 items) are averaged to yield a score from 1 to 5, with higher values representing higher self-efficacy for exercise.
• Self-regulation [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in self-regulation as measured by the 26-item self-report Eating Behavior Inventory, from baseline to 3, and 6 months. Scores range from 26-130, with higher scores indicating more use of positive eating behaviors.
• Depressive symptoms [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in depressive symptoms, as measured by the self-report 20-tem Center for Epidemiological Studies Depression Scale (CES-D), from baseline to 3, and 6 months. Scores range from 0-60, with higher scores indicating more depressive symptoms.
• Stress [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in stress, as measured by the self-report 10-item Perceived Stress scale, from baseline to 3 and 6 months. Scores range from 0-40, with higher scores indicating greater stress.

• Minutes of moderate-to-vigorous physical activity [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in minutes of moderate-to-vigorous physical activity as measured by the Paffenbarger Physical Activity Questionnaire (self-report), from baseline to 3, and 6 months.
• Sedentary behavior [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in sedentary behavior as measured by the Sedentary Behavior Questionnaire for Adults, from baseline to 3, and 6 months.
• Physical food environment [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in healthy and unhealthy foods offered in the home as measured by a physical food environment self-report questionnaire, from baseline to 3, and 6 months.
• Social food environment [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in social food environment as measured by the Meals in our Household Questionnaire, from baseline to 3, and 6 months.
• Household food rules [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in household food rules as measured by 12 items from the Active Where Parent-Child Survey, from baseline to 3, and 6 months.
• Weight control self-efficacy [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in weight control self-efficacy using the 20-item Weight Efficacy Lifestyle Questionnaire, from baseline to 3, and 6 months.
• Self-efficacy for exercise [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in self-efficacy for exercise, as measured by the Self-Efficacy and Exercise Habits Survey, from baseline to 3, and 6 months.
• Self-regulation [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in self-regulation as measured by the Eating Behavior Inventory, from baseline to 3, and 6 months.
• Depressive symptoms [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in depressive symptoms, as measured by the Center for Epidemiological Studies Depression Scale (CES-D), from baseline to 3, and 6 months.
• Stress [ Time Frame: Baseline, 3 Months, 6 Months ]
  Change in stress, as measured by the Perceived Stress scale, from baseline to 3 and 6 months.

• Overweight and Obesity
• Overweight
• Obesity

• Behavioral: Simple
  Participants have three daily goals (weighing, dietary goal, activity goal), will self-monitor (weigh on Wi-Fi enabled scale, use a simplified form of tracking only high-calorie, high-fat foods in the study smartphone app, wear Fitbit activity tracker), will receive 4-5 tailored text messages each week, and will view weekly tailored feedback and lessons in smartphone app.
• Behavioral: Standard
  Participants have three daily goals (weighing, dietary goal, activity goal), will self-monitor (weigh on Wi-Fi enabled scale, track calorie intake, wear Fitbit activity tracker), will receive 4-5 tailored text messages each week, and will view weekly tailored feedback and lessons in smartphone app.

• Experimental: Simple
  This arm uses a simplified form of dietary tracking that involves tracking only high-calorie, high-fat foods, in addition to the core behavioral smartphone-delivered intervention that consists of weighing, physical activity, goal setting, adaptive text messages, tailored weekly feedback, and lessons.
  Intervention: Behavioral: Simple
• Experimental: Standard
  This arm uses standard calorie tracking, in addition to the core behavioral smartphone-delivered intervention that consists of weighing, physical activity, goal setting, adaptive text messages, tailored weekly feedback, and lessons.
  Intervention: Behavioral: Standard

Inclusion Criteria (parent):

• Currently age 21-55.
• Body mass index (BMI) of 25-50 kg/m².
• Have one child between the ages of 2-12.
• Own an iPhone running at least iOS11 with a data and text messaging plan.
• Have the ability to read, write, and speak English.

Inclusion Criteria (child):

• Currently age 2-12.

Exclusion Criteria (parent):

• Lost more than 10 pounds in the last 6 months.
• Currently participating in another nutrition or weight loss program.
• Currently meeting exercise recommendations of 150 minutes per week of moderate-to-vigorous physical activity.
• Currently pregnant or breastfeeding, pregnant within the past 6 months, or planning to become pregnant within the next 6 months.
• Planning to relocate in the next 8 months.
• Will be out of town for 2 weeks or more in the next 8 months.
• Cannot attend two visits at the UNC Weight Research Program clinic.
• Pre-existing medical condition(s) that preclude adherence to an unsupervised exercise program, as determined by items endorsed on the PAR-Q (Physical Activity Readiness Questionnaire).
• Treatment of diabetes with insulin or oral medications that may cause hypoglycemia.
• 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.
• Another member of the household (family member or roommate) is a participant or staff member in this study.