One in three college students have overweight or obesity and are in need of brief and simple weight loss interventions that complement their unstructured lifestyles. Implementation intentions, a strategy that connects a goal-aligned behavior to a cue, facilitate goal-attainment for a wide variety of health-behaviors, but have not been tested as a stand-alone treatment for weight loss in students. College students with overweight or obesity (N = 95) were randomized to one of three conditions: an implementation intention group (IMP), an enhanced implementation intention group (IMP+) that included text message reminders and fluency training (i.e., training for speed and accuracy), and a control goal intention group (GOL) for four weeks. Participants completed anthropometric and self-report assessments pre- and post-treatment as well as experience-sampling assessments during the study to assess how implementation intentions contribute more directly to behavior change

Obesity poses a serious public health concern. Thirty-five percent of college students are overweight/obese, putting them at increased risk of overweight and obesity in later adulthood. The study of effective interventions for weight loss has been neglected in this population, and those that have been assessed had high attrition due to time burden. Brief interventions are needed for weight loss in students with obesity to improve current weight status and prevent associated comorbidities in later adulthood.

Self-regulatory behaviors are necessary to achieve weight loss goals, specifically goal-striving behaviors that aid in the planning and execution of goal-aligned actions5. Implementation intentions are a widely-utilized self-regulatory goal striving strategy that function by creating a mental link between a critical environmental or internal retrieval cue and a goal-aligned behavior (e.g. "if I want dessert, then I will eat an apple"). Implementation intentions are effective because they 1) create a strong association between a goal-aligned behavior and a retrieval cue for that behavior, increasing the likelihood that the goal-aligned behavior will be accessed and employed when the cue is encountered, and 2) increase attention for and cognitive accessibility of the retrieval cue, thus increasing opportunities for goal-aligned action. Implementation intentions effectively facilitate health-related goal attainment with regard to diet and weight loss. However, mechanisms underlying implementation intentions may weaken when used in applied, naturalistic settings and when multiple implementation intentions are maintained, due to complexity and difficulty of goal achievement. Enhancements that strengthen implementation intention effects should improve use for clinically-relevant diet change and weight loss in applied interventions.

Strengthening these mechanisms via improved encoding and retrieval should help maintain potency.

Fluency training (i.e., training for speed and accuracy) improves encoding and retention of information14,15 and should strengthen the already present link between the cue and the goal-aligned behavior, facilitating employment of the predetermined behavior, even when competing goals are introduced in applied settings. Additionally, external reminders serve to support memory for and increase accessibility of the multiple cues, allowing for maximal opportunities for the goal-aligned behaviors to be retrieved and utilized. Given high use of mobile devices in college students, text message reminders can serve as external reminders in this population and have been used previously to complement implementation intention use.

Thus, this proposal aims to test the efficacy of an implementation intention intervention alone (IMP) and in combination with fluency training and text message reminders (IMP+) against a goal-intention control (GOL) on weight loss and dietary behaviors. A three-group randomized-controlled intervention paradigm will be employed across four weeks. Ecological momentary assessment (EMA), the repeated testing of participants in real time, will be used to provide a more in-depth snapshot of implementation intention usage and its role as the mechanism of change in the intervention. Work to date examining implementation intentions has been limited to the laboratory or has utilized retrospective self-report, which limit external validity and are susceptible to recall bias. This will be the first study to examine implementation intention use with the externally-valid measurement that EMA provides. Additionally, given literature that supports implementation intention use during periods when goal striving is challenged (e.g. negative mood, etc.), the study will additionally assess their efficacy during disruptive internal and external states. At post-treatment, weight and dietary change will be assessed. Students with overweight/obesity wanting to lose weight, but not currently enrolled in a weight loss program, will be assessed. Specifically, the study will:

Specific Aim 1: Evaluate the effects of IMP and IMP+ on weight (Specific Aim 1a) and diet (Specific Aim 1b). Participants in IMP and IMP+ will lose more weight and show greater diet improvements compared to individuals in GOL. Participants in IMP+ will lose more weight and show greater diet improvements compared to participants in the IMP.

Exploratory Aim: Explore effective use of implementation intentions as the underlying mechanism of treatment outcome and their successful employment when distractions threaten goal attainment.

Inclusion Criteria:

• BMI greater than or equal to 25
• Interest in losing weight
• Own a mobile Smart phone and willing to receive study text messages and download a mobile application

Exclusion Criteria:

• Currently participating in a formal weight loss program
• Meet diagnostic criteria for an eating disorder as measured by the Eating Disorder Diagnostic Scale