Timing of Meals for Weight Loss

While eating the majority of energy earlier in the day appears to have a positive effect on weight and cardiometabolic outcomes, it is not clear how eating earlier in the day influences other behaviors that have a circadian rhythm (sleep), other energy balance behaviors important for weight loss (physical activity), and self-reported feelings of appetite control (hunger and fullness). Thus the purpose of this study is to examine the influence of timing of eating on sleep patterns, physical activity, and self-reported feelings of appetite control. It is hypothesized that those who eat the majority of their calories earlier in the day will have greater weight loss than those who eat the majority later in the day.

Thirty adults will be provided an 8-week standard lifestyle intervention, that includes a 1200-1500 kcal/day, \< 30% energy from fat dietary prescription, and a physical activity goal of 200 minutes/week. Participants will be randomized to one of two conditions differing in timing of energy consumed during eating bouts. Both conditions will limit the number of eating bouts/day to three. Participants will be instructed to eat their first eating bout within one hour of awakening and to consume their second and third eating bouts within five or six hours of their previous bout. Participants will be discouraged from eating at least one hour prior to going to sleep. During the intervention, participants will be instructed to self-monitor the time they wake up, the time of the start of each eating bout, and time they go to bed, as well as foods and beverages, and portion sizes, consumed. One condition will consume more energy earlier in the day (MORNING), thus energy intake will be split amongst the three eating bouts with 50% in the first bout, 30% in the second bout, and 20% in the last bout. The second condition will consume more energy later in the day (EVENING), thus energy intake will be split amongst the three eating bouts with 20% in the first bout, 30% in the second bout, and 50% in the last bout.

Eligibility Criteria:
Inclusion Criteria:

* body mass index (BMI) between 27 and 45 kg/m2
* normal self-reported daily (weekday and weekend) wake-up time between 5 am and 8 am
* normal, self-reported weekend wake-up time within two hours of their normal, self-reported weekday wake-up time
* regularly (at least five nights/week) get at least six total hours of self-reported sleep

Exclusion Criteria:

* report a heart condition, chest pain during periods of activity or rest, or loss of consciousness on the Physical Activity Readiness Questionnaire (PAR-Q)
* report being unable to walk for 2 blocks (1/4 mile) without stopping
* are currently participating in a weight loss program and/or taking weight loss medication or lost \> 5% of body weight during the past 6 months
* are diagnosed with type 1 or 2 diabetes
* have had bariatric surgery or are planning to have bariatric surgery within the next 4 months
* intend to move outside of the metropolitan area within the time frame of the investigation
* are pregnant, lactating, \< 6 months post-partum, or plan to become pregnant during the investigation
* are taking mediation to aid in sleep
* are shift workers/alternative shift workers that work outside of 7 am and 7 pm
* have a metal allergy (which would prevent the ability of participant to wear the SenseWear® armband from BodyMedia® used in the proposed study).