Time Restricted Feeding and Metabolic Rhythms (Rhythm)

Inclusion Criteria:

• Men and women with overweight and class I obesity (N=12, Age=20-50 years; BMI 25-35 kg/m2)
• Low physical activity level (≤150 min/wk of moderate-to-vigorous activity);
• For Females- Not currently pregnant or lactating and not pregnant within the past 6 months
• Habitually consume food over a window of >12 h/day;
• Pass a medical and physical screening performed by the study physician.
• Report a habitual, regular sleep-wake cycle for the month preceding screening that involved going to bed between 2200 and 0100h and getting up between 0600 and 0900 h with >7 h and <9.25 h in bed;
• Agree to eat control diets at imposed times for 1 week prior to the inpatient CTRC visits;
• Agree to keep a regular sleep/wake schedule for the duration of the study
• Possess a smart phone to install and utilize the meal timing application.

Exclusion Criteria:

• Subjects must not be currently participating in another research study that would influence their safe participation in this study. For example, subjects must not be participating in a research study in which they ingest experimental medication, or which involves blood samples, since both of these factors could increase risk of participation;
• Being considered unsafe to participate as determined by the study physician;
• Taking medications affecting weight, triglycerides, energy intake/energy expenditure, or sleep in the last 3 months;

• Having abnormal blood chemistry and/or hematology as deemed significant by the study physician;

  o Have one or more of the following out-of-range values measured on a fasting blood sample: glucose > 126 mg/dl, HbA1c > 6.5%, thyroid stimulating hormone <0.5 or >5.0 uU/ml. Subjects who may be anemic (hemoglobin <14.5 g/dl men, <12.3 g/dl women), have abnormal liver function tests (alanine amino transferase > 47 U/l, aspartate aminotransferase, > 47 U/l, alkaline phosphatase <39 or >117 U/l) or creatinine (>1.1 mg/dl)

• Significant abnormality in clinical laboratory values
• Ever having a history of systemic, psychiatric, neurological disease, or drug and alcohol abuse;
• History of cardiovascular disease, diabetes, uncontrolled hypertension, untreated thyroid, renal, hepatic diseases, dyslipidemia or any other medical condition affecting weight or lipid metabolism;
• Score > 18 on Beck Depression Index (BDI) will require further assessment by the study physician to determine if it is appropriate for the subject to participate in the study;
• Use of a continuous positive airway pressure (CPAP) device for the treatment of obstructive sleep apnea (OSA). A score of >10 on the Epworth sleepiness scale or >5 on the Pittsburgh Sleep Quality Index will require further assessment by the study physician to determine if it is appropriate for the subject to participate in the study;
• Being positive for human immunodeficiency virus or hepatitis B or C;
• Being a smoker or having been a smoker in the previous 6 months;
• Abnormal eating patterns identified by registered dietician interview (dietary fat<15%, dietary fat>45%, dietary protein >30%);
• Working night shifts;
• Night eating syndrome (at least 25% of food intake is consumed after the evening meal and/or at least two episodes of nocturnal eating per week);
• Traveling > 2 time zones 2 weeks prior to an inpatient CTRC study visit;
• Currently participating in any formal weight loss or physical activity programs or clinical trials.
• Having a clinically significant allergy (e.g., to food stuffs such as shellfish, peanuts);
• Celiac disease or known sensitivity to gluten (the metabolic kitchen is not gluten free certified and cannot accommodate this dietary restriction)