Effect of a Low-carb Dietary Intervention in Obese Patients: a Pilot Trial

Inclusion Criteria: Group A: HEALTHY LEAN CONTROLS * Healthy normal weight subjects with a body-mass index of 19.0-24.9kg/m2, HbA1C \<5.7% and fasting glucose \<5.6 mmol/l * Normal eating habits * Stable body weight for at least three months * Informed Consent as documented by signature Group B: PRE-DIABETIC or DIABETIC OBESE * Pre-diabetic/Diabetic obese with a HbA1C \>5.7% and/or fasting glucose \>5.6 mmol/l) and body-mass index \> 30kg/m2, otherwise healthy * Normal eating habits * Stable body weight for at least three months * Informed Consent as documented by signature Exclusion Criteria: Group A: HEALTHY LEAN CONTROLS * Pre-existing low carb diet (less than 45% of daily energy intake by carbohydrates) * Pre-existing diet (vegetarian, vegan, gluten-free etc.) * Psychiatric illness * Alcohol abuse, (smoking allowed) * Regular intake of medications, (oral contraceptives allowed) * Intake of antibiotics within the last 3 months before inclusion * Regular intake of pro- or prebiotics * Chronic diseases of the gastrointestinal tract, history of gastrointestinal surgery with major changes to the gastrointestinal tract (e.g. bariatric surgery) * Clinically relevant acute or chronic inflammatory disease * Pregnancy * Participation in another study with investigational drug within the 30 days preceding and during the present study. Group B: PRE-DIABETIC or DIABETIC OBESE * Pre-existing low carb diet (less than 45% of daily energy intake by carbohydrates) * Pre-existing diet (vegetarian, vegan, gluten-free etc.) * Psychiatric illness * Alcohol abuse, (smoking allowed) * Regular intake of medications (except: oral contraceptives, metformin, SGLT-2, statins, and antihypertensive, which are allowed) * Intake of antibiotics within the last 3 months before inclusion * Regular intake of pro- or prebiotics * Chronic diseases of the gastrointestinal tract, history of gastrointestinal surgery with major changes to the gastrointestinal tract (e.g. bariatric surgery) * Clinically relevant acute or chronic inflammatory disease * Pregnancy * Participation in another study with investigational drug within the 30 days preceding and during the present study.