Eight-hour early versus late eating windows to improve blood sugar and cardiometabolic health in overweight adults

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This is a crossover dietary intervention where participants follow two 5-week hypocaloric, 8-hour eating-window diets: one window predominantly in the morning (early TRE) and one predominantly in the afternoon (late TRE). A 10–12 week washout separates the intervention periods to reduce carryover effects. The study measures glucose metabolism and a range of cardiometabolic parameters, and collects biological samples to explore molecular mechanisms. Participants include adults with BMI 25–40 kg/m² who have normal glucose, prediabetes, or type 2 diabetes not treated with insulin.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Overweight or obesity (BMI 25-40 kg/m²)
* Healthy glucose metabolism (fasting glucose \<100 mg/dl and glucose after 2 hours OGTT \<140 mg/dl)
* OR impaired glucose metabolism (fasting glucose 100-125 mg/dl and/or glucose after 2 hours OGTT 140-199 mg/dl and/or HbA1c 5.7-6.4%)
* OR type 2 diabetes (according to existing medical diagnosis or fasting glucose \>126 mg/dl and/or glucose after 2 hours OGTT \>200 mg/dl and/or HbA1c ≥6.5%)
* Daily eating window ≥12 hours

Exclusion Criteria:

* Weight changes \> 5% within past 3 months
* Shift work
* Traveling across more than one time zone within one month prior to the study
* Pregnancy and breastfeeding
* Eating disorders, food intolerance/allergy to ingredients in the diet product, vegan diet, practicing time-restricted eating
* Severe chronic illnesses or other conditions that are incompatible with the planned intervention and examination program (e.g. type 1 diabetes, recent cardiovascular event, malabsorption, cancer in the last two years, etc.)
* Treatment with insulin, sulfonylureas, and GLP-1 receptor agonists, steroid use (oral, cutaneous, or parenteral), regular intake of melatonin, anticoagulation treatment that cannot be paused
* Extreme early and extreme late chronotypes

Where it's running

• German Institute of Human Nutrition Potsdam-Rehbruecke
  Nuthetal, Germany Recruiting

Study contacts

• Study coordinator: Olga Ramich, Prof. Dr.
• Email: olga.ramich@dife.de
• Phone: +49 33200 882749

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.