The objective of this study is to investigate the impact of hypocaloric time-restricted eating (TRE) at different day times (early versus late TRE) on glucose metabolism and other cardiometabolic parameters in individuals with overweight and with normal, or impaired glucose metabolism (prediabetes and type 2 diabetes). In addition, the study aims to elucidate the molecular mechanisms underlying these effects.
This dietary intervention study will follow a crossover design. During the intervention phases, participants will restrict their dietary intake to a defined eating window of 8 hours - predominantly in the morning (early TRE) or predominantly in the afternoon (late TRE) - in conjunction with a moderate caloric restriction for five weeks. A 10-12-week washout phase will separate the intervention periods. Overweight and obese individuals with healthy glucose metabolism, prediabetes, or non-insulin-treated type 2 diabetes will be recruited for the study.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
30
Participants will restrict their eating window (8 hours eating and 16 hours fasting per day) and caloric intake moderately. During the early TRE intervention, participants will primarily consume their meals in the morning. The precise eating window will be defined based on the individual chronotype of the participants. Additionally, participants will be required to reduce their daily caloric consumption by 25%. They will replace one daily meal with a calorie-reduced product to facilitate caloric restriction.
Participants will restrict their eating window (8 hours eating and 16 hours fasting per day) and caloric intake moderately. During the late TRE intervention, participants will primarily consume their meals in the evening. The precise eating window will be defined based on the individual chronotype of the participants. Additionally, participants will be required to reduce their daily caloric consumption by 25%. They will replace one daily meal with a calorie-reduced product to facilitate caloric restriction.
German Institute of Human Nutrition Potsdam-Rehbruecke
Nuthetal, Germany
RECRUITINGMean 24-hour glucose
Mean 24-hour glucose assessed by continuous glucose monitoring (CGM)
Time frame: 5 weeks
Glycemic variability
Inter- and intraday indices of glycemic variability assessed by CGM
Time frame: 5 weeks
Glucose levels
Fasting and postprandial glucose \[mg/dL\] in response to a mixed meal tolerance test
Time frame: 5 weeks
Insulin levels
Fasting and postprandial insulin \[mU/L\] in response to a mixed meal tolerance test
Time frame: 5 weeks
Glucagon levels
Fasting and postprandial glucagon \[pmol/L\] in response to a mixed meal tolerance test
Time frame: 5 weeks
Insulin resistance
Insulin resistance, as assessed by HOMA-IR \[AU\]
Time frame: 5 weeks
Insulin secretion
Insulin secretion, as assessed with the insulinogenic index \[AU\]
Time frame: 5 weeks
Body weight
Body weight \[kg\], as measured by scale weight
Time frame: 5 weeks
Body Mass Index (BMI)
BMI \[kg/m2\], calculated as weight/square height
Time frame: 5 weeks
Waist and hip circumference
Waist and hip circumference \[cm\] measured by tape
Time frame: 5 weeks
Body composition
Body fat mass and lean mass \[kg\], as measured by bioelectrical impendance analysis (BIA)
Time frame: 5 weeks
Fasting cholesterol
Fasting total cholesterol, low-density lipoprotein and high-density lipoprotein cholesterol \[mmol/L\]
Time frame: 5 weeks
Fasting triglycerides
Fasting triglycerides \[mmol/L\]
Time frame: 5 weeks
Blood pressure
Systolic and diastolic blood pressure \[mm Hg\], as measured by manometer
Time frame: 5 weeks
Resting energy expenditure
Resting energy expenditure \[kcal/day\], as assessed by indirect calorimetry
Time frame: 5 weeks
Gene expresssion in adipose tissue
RNAseq analysis of subcutaneous adipose tissue samples
Time frame: 5 weeks
Inflammatory markers in blood and adipose tissue
Levels of adipokines and inflammatory markers measured in blood samples and subcutaneous adipose tissue samples
Time frame: 5 weeks
Subjective satiety and hunger sensation
Satiety and hunger scores assessed using Visual Analog Scales (VAS, with a scale of 1-100, where higher values correspond to stronger satiety/hunger)
Time frame: 5 weeks
Concentration of satiety and hunger regulating hormones
Levels of ghrelin and peptide YY (PYY), as measured in blood samples in \[pg/mL\]
Time frame: 5 weeks
Species and strain-level microbiome changes
Species and strain-level microbiome changes, as assessed by 16S rRNA gene sequencing of stool samples
Time frame: 5 weeks
Levels of microbiome-derived metabolites
Levels of microbiome-derived metabolites measured in stool samples and blood plasma
Time frame: 5 weeks
Sleep quality
Sleep quality as assessed by the Pittsburgh Sleep Quality Index (PSQI score, which ranges from 0-21, where higher values correspond to worse sleep quality) and also monitored by an ActiGraph device
Time frame: 5 weeks
Sleep and wake timing
Sleep onset and offset assessed by the Pittsburgh Sleep Quality Index (PSQI score, which ranges from 0-21, where higher values correspond to worse sleep quality) and in addition by using a sleep diary
Time frame: 5 weeks
Internal circadian phase
Internal circadian phase as assessed using the BodyTime assay in peripheral mononuclear blood cells (PBMCs)
Time frame: Screening visit (week 0)
Glucagon-like peptide-1 levels
Fasting and postprandial glucagon-like peptide-1 (GLP-1) in response to a mixed meal tolerance test \[pM\]
Time frame: 5 weeks
Gastric inhibitory polypeptide
Fasting and postprandial gastric inhibitory polypeptide (GIP) in response to a mixed meal tolerance test \[pg/mL\]
Time frame: 5 weeks
Gene expresssion in peripheral mononuclear blood cells (PBMCs)
RNAseq analysis of clock, metabolic and inflammatory gene expression peripheral mononuclear blood cells (PBMCs)
Time frame: 5 weeks
Malondialdehyde
Plasma malondialdehyde \[µmol/L\]
Time frame: 5 weeks
3-nitrotyrosine
Plasma 3-nitrotyrosine \[pmol/mg\]
Time frame: 5 weeks
Protein carbonyls
Plasma protein carbonyls \[nmol/mg\]
Time frame: 5 weeks
36-item Short Form Health Survey (SF-36) to measure health-related quality-of-life
Health-related quality-of-life, as assessed by the 36-Item Short Form Health Survey (SF-36, with scores ranging from 0 to 100, with a higher score defining a more favorable health state)
Time frame: 5 weeks
Satisfaction with the intervention
Satisfaction with the intervention assessed by a 5-point Likert scale (with 5 representing "Very satisfied" and 1 representing "Very dissatisfied")
Time frame: 5 weeks
Decision behavior
Impulsiveness assessed by decision making tasks on computer
Time frame: 5 weeks
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