The main objective of the study is to gain insight in the early dynamics and mechanisms of recovery of liver disease and sex steroid metabolism during weight loss in obese men and women and to investigate whether surgical weight loss has differential effects as compared to weight loss with life style measures. In addition, we want to evaluate the postprandial hypoglycemic reactive syndrome (PPHRS) in these patients using a standard chewable meal.

Secondary objectives are investigating determinants for the changes in sex steroids, liver disease and PPHRS. Possible determinants to be investigated are adipocytokine secretion patterns, body composition, resting metabolism rate, weight loss per se and changes in fat distribution, parameters of fatty acid metabolism, … .

Inclusion Criteria:

• Informed consent obtained
• BMI > 35 kg/m²

Exclusion Criteria:

• Primary or secondary hypogonadism due to genetic causes (Kallman syndrome etc.), tumors, infiltrative diseases, infections, pituitary apoplexy, trauma, critical illness, chronic systemic illness or intentional.
• Type 2 Diabetes Mellitus treated with insulin or GLP-1 analogues
• Current or recent use of insulin, corticosteroids, opiates (on a daily basis), growth hormones, androgen- or estrogen analogs, levothyroxine, anti-retroviral drugs or antipsychotics
• Cancer (within < 5 years)
• High-grade malignancies
• Serious co-morbidities such as renal, hepatic of cardiac failure
• Known or suspected abuse of alcohol or narcotics
• Mental incapacity, unwillingness, or language barrier precluding adequate understanding or cooperation.

Patients with obesity class 3 who want to reduce weight