The overall objective of the study is to examine the effect of an 8-hour time-restricted eating intervention on lipid levels and body composition in peri- and recently postmenopausal women with untreated dyslipidemia.

This is a randomized controlled trial investigating the effects of an 8-TRE intervention compared to ad libitum eating (control) on metabolic health and body composition in recently postmenopausal women with untreated dyslipidemia. Following a 1-week baseline assessment, participants will be randomized to either a TRE or unrestricted control diet schedule (1-to-1 ratio) for 8 weeks. At baseline and weeks 4 and 8 of the intervention, daily eating and sleep patterns will be assessed for one week, followed by collection of fasting lipids and metabolic labs, body weight and vital signs; questionnaires assessing sleep and mood health, actigraphy and body composition via whole-body dual-energy x-ray absorptiometry will be assessed at baseline and week 8.

Inclusion Criteria:

• Healthy women aged 40-58 years
• Perimenopausal or recently postmenopausal, >1 year and <5 years
• BMI > 30 kg/m2
• Dyslipidemic, defined as the presence of one or more lipid-based cardiovascular disease risk-enhancing factors per American College of Cardiology/American Heart Association guidelines
• Normal renal and hepatic function
• Perimenopausal women, a negative pregnancy test

Exclusion Criteria:

Dietary factors:

• Diagnosis, or strong clinical suspicion, of eating disorders, including but not limited to, anorexia nervosa, bulimia nervosa, binge eating disorder
• Concurrent dietary intervention or modification unrelated to study procedures

Psychiatric factors:

• Current major depressive episode
• Suicidal ideation
• Lifetime history of bipolar disorder, psychosis, or other serious mental health problem
• Current alcohol/substance use disorder

Medical factors:

• Use of lipid-lowering or lipid-enhancing medications
• Use of systemic hormonal (estrogens and/or progestin) therapies
• Use of weight loss medications or supplements
• Use of medications that may cause weight loss or gain, unless body weight and medication usage remained stable for at least 6 months
• Previous weight loss surgery
• Abnormal vital signs at screening visit
• Body weight > 350 pounds, per DXA scan limits
• Malignancy within past 2 years
• Major surgery within past 3 months
• Medical instability considered to interfere with study procedures
• Contraindications to DXA scanning
• Use of medications that have the potential to cause hypoglycemia (e.g., insulin, sulfonylureas)
• Undergoing treatment for cancer
• Use of medications for which time-restricted eating would interfere with recommended timing of medication ingestion with food intake.

Lifestyle and other factors:

• Irregular sleep/wake schedule
• Shiftwork
• Recent travel across 2 or more time zones
• Recent change in exercise habits
• Work or social schedules that would impede ability to adhere to study protocol

Adherence factors:

-Inability to adhere to study procedures completed between screening and randomization visits

Off-Study Criteria:

• Initiation of new medications for lipid management, weight loss, hormonal medications, or other medications that may cause changes in weight or lipid levels
• Development of any significant medical problem
• Enrollment in another clinical trial involving study procedures or medications that might interfere with study procedures.
• Significant deviation from study protocol or protocol violation
• Inability to adhere to time-restricted eating window

Blood tests and assays, DXA scans, body weight, vitals, etc. are performed by assessors blinded to the condition and aims of the study.