This study is designed as an observational trial. The objective of this study is to follow-up with participants 3 years after completion of an 18-month comprehensive behavioral weight loss intervention. Outcomes of interest include change in body weight, body composition, physical activity, energy intake, and sleep. In addition, investigators will explore the associations between current physical activity, sleep, and energy intake patterns and body weight regulation.

A total of 170 participants were initially enrolled in the comprehensive behavioral weight loss intervention.In this study, investigators will conduct a follow-up visit 3 years after the completion of the intervention. Only participants who completed the behavioral weight loss intervention will be enrolled in this study. Participants will undergo testing of body weight, body composition, physical activity patterns, energy intake patterns, sleep patterns, resting metabolic rate, and total daily energy expenditure.

Inclusion Criteria:

• Previous enrollment in standard behavioral weight loss intervention (NCT01985568 or NCT03411356)
• Age 20-60 (This age range has been selected based upon the participants enrolled in the Parent Trial)
• Capable and willing to give informed consent
• Possess a smartphone to install and utilize the meal timing application
• Capable and willing to wear the Actigraph, ActivPAL and Actiwatch-2 for 24 hours/day for 28 consecutive days
• Willing to complete the Total Daily Energy Expenditure (TDEE) assessment which includes multiple urine collections and drinking stable water isotopes

Exclusion Criteria:

• Being considered unsafe to participate as determined by the study physician (Dr. Catennaci)
• New diagnosis of a medical condition (not observed in the Parent Trial) which may affect weight or energy metabolism (e.g. depression, CVD, diabetes, uncontrolled hypertension, untreated thyroid, renal, hepatic diseases)
• Women who became pregnant after completing the Parent Trial
• Current use or use within the last 6 months of prescription or over-the-counter medications known to affect appetite, weight, and sleep

Participants previously enrolled in an 18-month behavioral weight loss intervention at the University of Colorado Anschutz Medical Campus. (NCT01985568)