The Enlighten study is an 8-week trial investigating the response to use of a smartphone diet and activity application. Participants are enrolled as part of a worksite intervention, and will receive the LoseIt! weight loss smartphone application, which requires participants to self-monitor dietary intake and physical activity, a component shown to effectively produce weight loss. The application will be programmed to deliver dietary intake recommendations during the first three weeks of the intervention. At the 3 week time point, self-monitoring adherence via the smartphone application will be assessed and those who are not responding will receive 4 weekly telephone coaching sessions. Those individuals who respond at the end of 3 weeks will be encouraged to continue self-monitoring on the application. All participants will also receive regular text messages throughout the trial. The importance of the proposed research lies in the objective to reconfigure weight loss treatment so as to achieve the intended outcome more efficiently and in a manner that allows greater reach.

Inclusion Criteria:

• BMI greater than 25-39.9 kg/m2
• Weigh no more than 300 pounds.
• Weight stable (no loss or gain >25 lbs for the past 6 months)
• Not enrolled in any formal weight loss program
• Not currently taking anti-obesity medications
• Interested in losing weight
• Own an Android Smartphone or iPhone, be willing to install the Lose It! Application, and agree to join the Enlighten group which will allow study staff to view participant data using a private coaching interface.

Exclusion Criteria:

• Unstable medical conditions (uncontrolled hypertension, diabetes, unstable angina pectoris, myocardial infarction, transient ischemic attack, cancer undergoing active treatment, or cerebrovascular accident within the past six months)
• History of diabetes requiring insulin supplementation
• Crohn's Disease
• Diagnosis of obstructive sleep apnea requiring intervention (i.e. CPAP)
• Require use of an assistive device for mobility (e.g., wheelchair, walker, cane)
• BMI greater than or equal to 40, weight greater than or equal to 300 pounds
• Hospitalization for a psychiatric disorder within the past 5 years
• Those at risk for adverse cardiovascular (CVD) events with moderate intensity activity
• Those who cannot read the study questionnaires will be excluded
• Those currently taking weight loss medication or committed to following an incompatible dietary regimen.
• Female participants may not be pregnant, trying to get pregnant, or lactating.
• Bulimia Nervosa
• Binge Eating Disorder
• Active Suicidal Ideation
• those on medications known to cause weight gain (e.g., prednisone)
• current substance abuse or dependence besides nicotine dependence
• low motivation to change that would interfere with program adherence