Dinner Time for Obesity and Prediabetes

Obesity and its metabolic complications are leading causes of global morbidity and mortality. Evidence is mounting that inappropriate timing of food intake contributes to obesity. Specifically, late eating is associated with greater weight gain and metabolic syndrome. However, the mechanism by which late eating harms metabolism is not fully understood but may be related to mis-timing of food intake in relation to the body's endogenous circadian rhythm. Conversely, harmonization of eating timing with endogenous circadian rhythm may optimize metabolic health. In this study the investigators will use gold-standard methods of characterizing circadian rhythm in humans to examine the metabolic impacts food timing relative to endogenous circadian rhythm.

Inclusion Criteria:For the Normal-Weight Healthy (NWH) cohort: Healthy male and female adults, age 18-50, with BMI 18-24.9 kg/m2 inclusivelyFor the Obesity-Prediabetes (OPD) cohort: Male and female adults, age 18-50, with BMI ≥30 kg/m2 and prediabetesAll participants must be able to understand study procedures and to comply with the procedures for the entire length of the study.Exclusion Criteria:Sleep disorder including insomnia, untreated moderate-severe sleep apnea, restless leg syndrome, or narcolepsyNight shift workExtreme delayed sleep phase defined as self-reported routine bedtime later than 1:00 AM or having mid-sleep on free days later than 5:00 AM on the Munich Chronotype Questionnaire (MCTQ) or DLMO later than 24:00Gastroesophageal reflux disease that affects ability to tolerate a dinner close to bedtimeActive smokingCurrent drug or alcohol use or dependence that, in the opinion of the site investigator, would interfere with adherence to study requirements.Diabetes (type 1 or 2) or on any diabetes medications besides metforminEvidence of metabolic or cardiovascular disease, or disease that may influence metabolism (e.g. cancer, thyroid disease)Hemoglobin A1c ≥5.7% for NWH cohort; Hemoglobin A1c ≥6.5% for OPD cohortHemoglobin < 10 g/dLSelf-reported kidney diseaseAny known history of an inherited metabolic disorderPregnant or lactating female (pregnancy test will be required prior to metabolic visits)Peri-menopausal or post-menopausal female as determined by follicle stimulating hormone of > 30 mIU/mL or fewer than 3 menstrual periods in 6 monthsProfessional or collegiate athleteTravel across >1 time zone within a 3-month period before and during the protocolWeight less than 40 kg or more than 180 kgGastrointestinal disorders that can lead to obstruction of the digestive tract (i.e. diverticular disease, history of bowel obstruction, inflammatory bowel disease, motility disorder)History of any surgical procedures in the gastrointestinal tract.Swallowing disordersTaking any prescription medication or other drug that may influence metabolism (e.g. diet/weight-loss medication, asthma medication, blood pressure medication, psychiatric medications, corticosteroids, or other medications at the discretion of the PI and/or study team)Chronic use of sedative hypnotics, anxiolytics, opiatesUse of medications that can affect circadian rhythm (beta blockers, melatonin)Presence of a cardiac pacemaker or other implanted electro-medical devicesThose who have to undergo strong electromagnetic field during the period of use of the ingestible thermosensor (i.e. MRI)Weight loss or gain of ≥ 5% of total body weight over the preceding 3 monthsCurrently participating in a weight loss programPrior bariatric surgeryVolunteers with strict dietary concerns (e.g. vegetarian or kosher diet, food allergies)History of significant intravenous access issuesNon-English speaking individuals: The complexity of the instructions for various components of the study would make the study procedures difficult to follow in the setting of a language barrier.Other conditions or situations at the discretion of the PI