Time Restricted Eating for Weight Management

A 12-month randomized, controlled, parallel-arm trial, divided into 2 consecutive periods: (1) 6-month weight loss period; and (2) 6-month weight maintenance, will be implemented. Adults with obesity will be randomized to 1 of 3 groups: (1) 8h-TRE, ad libitum food intake from 12pm to 8 pm, fasting from 8 pm to 12 pm daily, (2) CR, 25% energy restriction every day; or 3) control, ad libitum food intake daily, eating within more than 10 hours per day.

Time restricted eating (TRE) has become a popular weight loss regimen. The sudden rise in popularity of TRE is mostly likely due to is its sheer simplicity, and the fact that it does not require individuals to count calories in order to lose weight. Participants are simply asked to consume all food within a specified time frame and fast with energy free beverages for the remaining hours of the day. Evidence shows that when people with obesity limit their eating window to 6 to 8 hours per day, they naturally reduce energy intake by 350-500 calories. From a clinical standpoint, these findings are paramount. One of the main reasons for subject attrition with traditional dieting, i.e. daily calorie restriction (CR), is frustration with having to count calories every day. TRE regimens are able to side-step this requirement by allowing participants to simply "watch the clock" instead of monitoring calories, while still producing significant weight loss and metabolic health improvements. This feature of TRE has the potential to improve long-term adherence to the diet, and in turn produce lasting weight control in adults with obesity.

Accordingly, we conducted a one-year, randomized, controlled trial to compare the effects of late TRE (eating all food between 12:00 pm to 8:00 pm, without calorie counting), versus CR (25% energy restriction daily), and a control group eating over a period of 10 or more hours, on body weight and metabolic risk factors in a diverse group of American adults with obesity. We hypothesized that the TRE group would achieve greater weight loss, and experience more pronounced improvements in insulin sensitivity during the 6-month weight loss phase, compared to CR and control participants. We also hypothesized that the TRE group would better maintain their weight loss and sustain their improvements in insulin sensitivity during the 6-month weight maintenance phase, when compared to the CR and control participants.

Eligibility Criteria:
Inclusion criteria:

* Age between 18 to 65 years old
* BMI between 30 and 50 kg/m2
* Sedentary or lightly active (\<60 minutes/week of light activity for the 3 months prior to the study)

Exclusion criteria:

* • Type 1 DM or Type 2 DM
* History of eating disorders (anorexia, bulimia, or binge eating disorder)
* Are not weight stable for 3 months prior to the beginning of study (weight gain or loss \> 4 kg)
* Are not able to keep a food diary or activity log for 7 consecutive days during screening
* Are taking drugs that influence study outcomes (weight loss, glucose-lowering medications)
* Are perimenopausal or have an irregular menstrual cycle (menses that does not appear every 27-32 days)
* Are eating within less than a 10-hour window at baseline
* Are pregnant, or trying to become pregnant
* Are night shift workers
* Are smokers