Effect of Time-Restricted Feeding on Fat Loss and Cardiometabolic Risk Factors in Overweight Adults

Percent of weight lost as fat, as measured by dual-energy X-ray absorptiometry (DXA). Lean mass retention will be quantified as 100% minus percent of weight lost as fat (i.e., is measured in the same units).

Change in body weight (kg), as measured by scale weight

Changes in total fat mass, lean mass, bone mass, and regional values (kg), as measured by DXA. (This will be secondary to the assessment of fat loss and lean mass retention as specified above.)

Fasting glucose (mg/dl)

Fasting insulin (IU/L)

HbA1c (%)

Total cholesterol (mg/dl), LDL cholesterol (mg/dl), HDL cholesterol (mg/dl), and triglycerides (mg/dl)

Systolic and diastolic blood pressure (mm Hg)

Heart rate in beats per minute

Waist circumference (cm)

Hunger and fullness as measured by Likert (1-5 scale) and visual analog scales (a 0-100 scale, with 0 meaning "Not at all" and 100 meaning "Extremely")

Energy intake and food intake in kcal/day, as measured using Remote Food Photography Method (RFPM)

% of calories as fat, carbohydrate, and protein, as measured using RFPM

Number of meals and snacks per day, as measured using RFPM

Clock times of meals and snacks, as measured using RFPM

Start and stop times and mid-points of daily eating in clock time, as assessed by the daily adherence survey

Average duration of the daily eating period (hours), as measured by the daily adherence survey

Distribution of calories eaten across the day in % per time period, as measured by a novel questionnaire that is being validated

Presence and degree of breakfast and nighttime eating, as measured by a novel questionnaire that is being validated

Self-reported adherence rate in days per week

Reasons for non-adherence, as measured by the daily adherence survey

Attrition rate (%)

Depression as measured by the Patient Health Questionnaire-9. (Each question is scored on a 0-3 scale, where 0 means "Not at all" and 3 means "Nearly every day." Answers to each question are tallied to create a single composite score of depression from 0-27, with higher values meaning more depressive symptoms.)

Mood states as measured by the Profile of Mood States (a 5-point scale with 1 meaning "Not at all" and 5 meaning "Extremely"). This study is particularly interested in the scores for anxiety and related moods.

Chronotype/mid-point of sleep (in clock time), as measured by the Munich Chronotype Questionnaire

Stimulant usage, as measured by the Munich Chronotype Questionnaire (in "servings" per time)

Sleep duration, as measured by the Pittsburgh Sleep Quality Index

Sleep quality, as assessed by the Pittsburgh Sleep Quality Index (PQSI) (This study will use the Global PQSI score, which ranges from 0-21, where higher values correspond to worse sleep quality.)

Restrained, emotional, and external eating, as measured by the Dutch Eating Behavior Questionnaire. (Individual questions are scored on a 5-point scale ranging from "Never" to "Very often," and composite scores for restrained, emotional, and external eating are tabulated, with higher numbers reflecting more of each trait.)

Loneliness, as measured by the UCLA Loneliness Scale (a 3-point scale with 1 meaning "hardly ever" and 3 meaning "often")

Intervention satisfaction and barriers and facilitators of adherence, as measured by qualitative exit interview

Social life and daily habits, as measured by the frequency of occurrence of social activities (5- and 8-point rating scales)

Physical activity status, as measured by the Baecke Physical Activity questionnaire

Plasma and salivary nitrate and nitrite (nM)

Salivary nitrate reductase activity (nmol / min / colony forming unit) in tongue swab samples

Salivary bacterial abundance (colony forming units) in tongue swab samples

24-hour urinary oxalate, citrate, sodium, calcium, chloride, potassium, and creatinine, as measured in mg/day

24-hour urinary phosphorus and uric acid, as measured in g/day

24-hour urinary aldosterone excretion (µg/12 hr)

12-hour urinary sodium and potassium (mmol/12 hr)

12-hour urinary endothelin (ng/12 hr)

12-hour urinary nitric oxide (mmol/12 hr)

12-hour urinary albumin (mg/12 hr)

12-hour urinary KIM-1 (pg/g creatinine or pg/12 hr)

12-hour urinary nephrin (ng/g creatinine or ng/12 hr)

12-hour albumin-to-creatinine ratio

12-hour urinary hydrogen peroxide and TBARs (µmol/g creatinine or µmol/12 hr)

Urinary exosomes (particles/ml)