Glp-1

(1) The first aim of this study is to determine whether prediction errors in reward learning are altered in obesity and if Glp-1 receptor activation affects this learning process as a possible mechanism contributing to reduced food intake under Glp-1 analogues in normal weight and obesity.

(2) On a behavioral level, the second aim of this study is to determine whether Glp-1 receptor activation alters the motivation to spend effort for food or monetary rewards in normal weight and obesity.

1. Informed consent obtained
2. Non-smoker (for the last 1 year not smoked more than 2 cigarettes per month)
3. Stable body weight (less than 5% self-reported change within the last 3 months)

• Lean subjects with a BMI between 20-25 kg/m² (healthy weight range)
• Obese subjects with a BMI above 30 kg/m²

1. Serious or unstable medical illness (e.g., cancer). Past or current history of alcoholism or consistent drug use. Current and history of major psychiatric illness as defined by the DSM-IV criteria including eating disorders
2. Medications that affect alertness (e.g., barbiturates, benzodiazepines, chloral hydrate, haloperidol, lithium, carbamazepine, phenytoin, etc.) and any psychoactive drugs or anti-obesity agents
3. History of major head trauma with loss of consciousness
4. Pregnancy
5. Nursing women
6. Kidney insufficiency (Kreatinin- Clearance <30 ml/min)
7. Reduced liver functioning
8. History of quincke edema
9. Family or personal history of multiple endocrine neoplasia type 2 (MEN2) or familial medullary thyroid carcinoma (FMTC)
10. Personal history of non-familial medullary thyroid carcinoma
11. History of acute or chronic pancreatitis
12. Any known food allergy, certain food sensitivities (lactose); allergy towards active ingredient
13. History of metalworking, injury with shrapnel or metal slivers, and major surgery
14. History of pacemaker or neuro stimulator implantation
15. Dysphagia
16. Weight >150 kg

One dose of 0.6 mg Liraglutid resp. placebo sc.