LIfestyle MEtabotype study b (LIME-B)

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Overweight or obese (BMI 25-40 kg/m²) * Good knowledge of German * Completion of the LIME screening visit; participants who do not take part in the further assessments of module A \[NCT07868601\] may still participate in module B Participants are classified into three groups based on the screening visit: * Group A (without Prediabetes or Type 2 Diabetes) Criteria: HbA1c \<5.7% and fasting plasma glucose \< 100 mg/dl * Group B (Prediabetes) Criteria: HbA1c 5.7-6.4%, or fasting plasma glucose 100-125 mg/dL * Group C (Type 2 Diabetes) Criteria: HbA1c ≥6.5%, fasting plasma glucose ≥ 126 mg/dl, or existing T2D diagnosis by physician, or T2D diagnosis based on an available result from standardized 75 g oral glucose tolerance test 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