Fat Absorption and Metabolism After Roux-en-Y Gastric Bypass

Inclusion criteria, RYGB * Age \> 18 years * RYGB \> 12 months prior to inclusion * Weight stable (± 3 kg during the last month) * HbA1c \< 48 mmol/mol before surgery, and no history of diabetes * HbA1c \< 48 mmol/mol and fasting plasma glucose \< 6.1 mmol/l at inclusion Inclusion criteria, CON * Age \> 18 years * No former bariatric surgery * Weight stable (± 3 kg during the last month) * HbA1c \< 48 mmol/mol, fasting plasma glucose \< 6.1, and no history of diabetes Exclusion criteria * Thyrotoxicosis or inadequately treated hypothyreosis * Haemoglobin \< 6.5 mmol/l at inclusion * Pregnancy (pregnancy test in fertile woman before enrolment) or breast feeding * Medication affecting the planned examinations which cannot be paused during the study period. * Adherence to extreme diets with excessively high or low contributions from certain macronutrients (e.g. ketogenic diet) * Complications restricting eating behavior (e.g. postprandial hypoglycemia, vomiting or strictures) * MR contraindications