Participants receive digital tools and education on weight gain prevention behaviors at baseline.

Changes in dietary intake from baseline up to 24 months will be assessed using the NCI Automated Self-Administered 24-hour Recall (ASA-24). Participants will complete one self-reported recall. Change in overall energy intake and saturated fat intake, as well as change in fruit and vegetable consumption, fiber consumption, and change in the Healthy Eating Inventory scores will be examined.

Change in physical activity from baseline up to 24 months as measured using 1 week of data collected using the Fitbit activity monitor during each assessment period including total minutes of activity and steps.

Change in perceived competence from baseline up to 24 months as measured using 2 items from the The Perceived Competence for Scale. The Scale measures perceived competence for diet (4 items) and physical activity (4 items) and there are two subscales (diet and physical activity). Items are rated on a 7-point Likert scale (1 = not at all true, 7 = very true). One item from each subscale will be measured: "I feel confident in my ability to maintain a healthy diet" and "I feel confident in my ability to exercise regularly." The range for each item in each subscale is 1 - 7 with greater values indicating higher levels of perceived competence for engaging in positive diet and physical activity behaviors.

The Centers for Disease Control and Prevention (CDC) Healthy Days Measure assesses a person's perceived sense of well-being through four questions on: 1) self-rated health, 2) number of recent days when physical health was not good, 3) number of recent days when mental health was not good, and 4) number of recent activity limitation days because of poor physical or mental health. Recent days is past 30.

Scoring for this measurement tool is limited to an unhealthy days summary index is calculated by adding numbers 2 and 3 above with a maximum of 30 with higher values indicating poorer health. For self-rated health, items include Excellent, Very Good, Good, Fair, and Poor. For items 2-4, a greater number of days indicates more poor health in each category.

Center for Epidemiological Studies Depression Scale-Short Form (CESD) is a self-report 10-item scale designed to measure current depressive symptoms. Total score range from 0-30, with a score at or above 10 reflecting significant depressive symptomatology.

Participants will be asked about frequency of use of 30 weight control strategies such as "I set a daily calorie goal for myself" used in the past month on a 5-point Likert scale from Never to Always. A total score is computed and ranges from 0 to 120 with higher scores indicating more frequent usage of the strategies. Factor analysis reflects a 4-factor structure: dietary choices, self-monitoring strategies, physical activity, and psychological coping.

The 4-item Perceived Stress Scale measures overall perceived stress during the past month. Items include how often you felt you could control the important things in your life, you felt confident about your ability to handle your personal problems, things were going your way, and you felt difficulties were piling up so you could not overcome them. Items are scored on as 5-point Likert scale from 0 (never) to 4 (very often). Scores range from 0 to 16, and higher scores indicate more stress.

Participants will respond to an item derived from the revised Questionnaire on Eating and Weight Patterns (QEWP-5) to assess loss of control eating. Loss of control eating is assessed by endorsing the behavior one or more times per week over the reference period.

Participants will respond to an items derived from the revised Questionnaire on Eating and Weight Patterns (QEWP-5) to assess compensatory behaviors. Compensatory behaviors are assessed as using any, on average, once per week during the reference period.

The scale, consists of five items assessing confidence in participating in exercise in the presence of barriers such as feeling tired, being in a bad mood, not having time, on vacation, and experiencing bad weather. Response options are on a five point Likert-scale, ranging from not confident (1) to extremely confident (5). The score is an average of each item with a higher score indicating higher self-efficacy. Scores range from 1 to 5 with 5 indicating higher self-efficacy.

We will adapt the 15-item Dietary Self-Regulation Questionnaire to assess reasons for starting or continuing to manage weight (The reason I would manage my weight is...". Items are rated on a 7 point Likert scale from 1 (not at all true) to 7 (very true). Subscales include autonomous motivation (1, 3, 6, 8, 11, 13), externally controlled motivation (2, 4, 7, 9, 12, 14), and amotivation (5, 10, 15). Responses for each subscale score are averaged and higher numbers indicate higher levels of that type of motivation. Subscale scores range from 1 to 7.

Self-regulation behaviors will be assessed using the 10-item Goal Setting subscale of the Short Self-Regulation Questionnaire. Items are scored on a 1-5 scale (1=strongly disagree to 5=strongly agree ) and are be summed to create a total score with a maximum of 50 with higher scores indicating greater goal setting behaviors.

The Weight Efficacy Lifestyle Questionnaire (WEL-Q)) Short Form will be used to assess participants' confidence in their ability to handle high-risk situations related to eating; 8 items ask participants to rate their confidence on an 11-point Likert scale ranging from 0 (not confident) to 10 (very confident). The WEL consists of five factors: negative emotions, availability, social pressure, physical discomfort, and positive activities. Items are summed for a total score (0-80). Higher scores indicated higher levels of self-efficacy for resisting eating.

The number of potential participants approached, eligible and enrolled will be measured. Participation rate will be determined by dividing the total number of enrolled participants by the total number eligible to enroll.

Representativeness will be assessed by comparing demographics, BMI and rank of those enrolled to: 1) those screened, eligible, and not enrolled and 2) to the demographics of the personnel at the study installations, the Air Force, and the US Military.

Fidelity of app usage: Will be measured by examining objective measures of logins, feature utilization, and content exposure.

Effectiveness will be measured primarily with the study's weight gain outcomes over time.

Effectiveness will also be measured by examining potential negative outcomes (e.g., loss of control eating and compensatory behavior, attrition) will also be used.

Potential for Organizational level Adoption will be estimated by summarizing stakeholders' willingness and perceptions of future adoption of SNAP-M for other bases and military branches.