Calorie restriction extends life span and prevents aging-related diseases in several species. Odorants from live yeast restrain the beneficial effects of calorie restriction in Drosophila Melanogaster. The investigators hypothesize that visual and odorous food stimuli impact the neuroendocrine and metabolic response to starvation in healthy humans.

In this randomized cross-over intervention study 12 healthy, young men will fast twice for 60-hours in the presence or absence of food-related visual and odorous stimuli. At baseline and on the last morning of each intervention an oral glucose tolerance test (OGTT) will be performed. During the OGTT blood is sampled and hypothalamic neuronal activity is measured by functional MRI.

Inclusion Criteria:

• Caucasian male volunteers
• Age > 18 years and < 70 years
• Body mass index (BMI) > 20 kg/m2 and < 25 kg/m2
• Fasting serum glucose (FSG) < 6.1 mmol/L

Exclusion Criteria:

• Any significant chronic of hereditary disease (including renal, hepatic or endocrine disease)
• Any significant abnormal laboratory results found during the medical screening procedure
• Any use of medication (except for NSAID)
• Anosmia or any other (acquired) loss of olfaction (ea. rhinitis)
• Recent weight changes or attempts to loose weight (> 3 kg weight gain or loss, within the last 3 months)
• Difficulties to insert an intravenous catheter
• Smoking
• MRI contraindications
• Recent blood donation (within the last 3 months)
• Recent participation in other research projects (within the last 3 months), participation in 2 or more projects in one year