Dinner Time for Obesity and Prediabetes (DTOP)

The investigators are enrolling both Normal-Weight Healthy (NWH) and Obesity-Prediabetes (OPD) research participants. At this time (5/2023) the investigators are focusing on the NWH group. Inclusion Criteria: For the Normal-Weight Healthy (NWH) cohort: Healthy male and female adults, age 18-50, with BMI 18-24.9 kg/m2 inclusively For the Obesity-Prediabetes (OPD) cohort: Male and female adults, age 18-50, with BMI ≥30 kg/m2 and prediabetes All 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 narcolepsy Night shift work Extreme 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 24:00 Gastroesophageal reflux disease that affects ability to tolerate a dinner close to bedtime Active smoking Current 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 metformin Evidence 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 cohort Hemoglobin < 10 g/dL Self-reported kidney disease Any known history of an inherited metabolic disorder Pregnant 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 months Professional or collegiate athlete Travel across >1 time zone within a 3-month period before and during the protocol Weight less than 40 kg or more than 180 kg Gastrointestinal 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 disorders Taking 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, opiates Use of medications that can affect circadian rhythm (beta blockers, melatonin) Presence of a cardiac pacemaker or other implanted electro-medical devices Those 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 months Currently participating in a weight loss program Prior bariatric surgery Volunteers with strict dietary concerns (e.g. vegetarian or kosher diet, food allergies) History of significant intravenous access issues Non-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