Time Restricted Eating (TRE) in Bipolar Disorder

Inclusion Criteria: * Adults (aged 18-65 years) * Diagnosed with bipolar disorder (i.e., subtype Bipolar I or II as assessed with the Quick SCID)21 * Currently experiencing depression (i.e., PHQ-9 ≥ 10)22 * Currently overweight (i.e., Body mass index (BMI) \> 30 kg/m2) * Provides Informed Consent Exclusion Criteria: 1. Dietary factors: 1. Diagnosis, or strong clinical suspicion, of eating disorders, including but not limited to, anorexia nervosa, bulimia nervosa, binge eating disorder (as assessed with the Quick SCID) 2. Concurrent dietary intervention or modification unrelated to study procedures 2. Psychiatric factors: 1. Severe depression (i.e., PHQ-9\>20) 2. Experiencing manic symptoms (i.e., ASRM \< 6)23 3. Active suicidal ideation (i.e., PHQ-9, item 9 \>2) 4. Current alcohol/substance use disorder (as assessed with the Quick SCID) 3. Medical factors: 1. Use of weight loss medications or supplements 2. Use of medications that may cause weight loss or gain, unless body weight and medication usage remained stable for at least 6 months 3. Previous weight loss surgery 4. Malignancy within past 2 years 5. Major surgery within past 3 months 6. Medical instability considered to interfere with study procedures 7. Use of medications that have the potential to cause hypoglycemia (e.g., insulin, sulfonylureas) 8. Undergoing treatment for cancer 9. Use of medications for which time restricted eating would interfere with recommended timing of medication ingestion with food intake. 4. Lifestyle and other factors: a. Work or social schedules that would impede ability to adhere to study protocol 5. Adherence factors: 1. Ability to adhere to study procedures