LIfestyle MEtabotype Study A

Glycemic responses vary significantly among individuals, even when consuming identical foods or meals, but the factors predicting individual glucose response to food intake remain poorly investigated. The aim of the LIfestyle MEtabotype study (LIME) observational study is to identify lifestyle-related and mechanistic factors which predict individual postprandial glucose fluctuations in individuals with different glycemic status (prediabetes, type 2 diabetes \[T2D\], and absence of prediabetes or T2D). To address this aim, the study will conduct a comprehensive lifestyle characterization and metabolic, molecular and neurocognitive phenotyping during study center visits and a dietary, glucose, sleep and activity monitoring during the observational phase.

Inclusion Criteria: * Overweight or obesity (BMI 25-40 kg/m²) * Good knowledge of German Exclusion Criteria: * Weight changes of more than 5% in the last 3 months * Night shift work * Travel across more than one time zone in the last month before and during study participation * Intensive regular physical activity of more than 2 hours per day * Current pregnancy or breastfeeding * Severe renal, liver or heart disease * Existing or past hematological malignancies, other malignant tumors, unless successfully treated more than 12 months before study start * Severe neurological or psychiatric disorders * Daily alcohol consumption of more than 20 grams or more than 150 grams per week * Use of illicit or legal drugs one week prior to study start and during study participation * Known systemic infections * Type 1 diabetes and rare forms of diabetes * Diabetes treatment with insulin or sulfonylureas or diabetes medication in the absence of manifest type 2 diabetes * Unstable thyroid dysfunction * Blood coagulation disorders or anticoagulation therapy that cannot be interrupted * Medications affecting nutrient absorption * Medications with immunosuppressants or steroids (oral or parenteral) * Current eating disorders, functional or structural digestive disorders or bariatric surgery * Food allergies or intolerances to ingredients of the test meals * Intermittent fasting or calorie-restricted diet four weeks prior to the start of the study or during the study * Ketogenic diet or ketogenic supplements four weeks prior to or during module B * Left-handedness * Severe claustrophobia * Electrical implants or non-removable metallic implants * Concurrent participation in another intervention study * Assessment by the study physician based on medical concerns precluding study participation