Investigators want to test whether the intake of the nucleoside inosine increases the human energy expenditure. Inosine occurs as a metabolic intermediate in the human body and is sometimes taken as a dietary supplement by athletes.

For this purpose, investigators will measure the basal metabolic rate by indirect calorimetry. Study participants will then take inosine dissolved in water or placebo and energy expenditure will be assessed again.

Inclusion Criteria:

• Healthy male volunteers
• BMI between 18-27 kg/m2
• Age between 18 and 40 years

Exclusion Criteria:

• Chronic concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, diabetes mellitus),
• Known or suspected non-compliance, drug or alcohol abuse,
• Inability to follow the procedures of the study
• Participation in another study with investigational drug within the 30 days preceding and during the present study,
• Previous enrolment into the current study,
• Enrolment of the investigator, his/her family members, employees and other dependent persons,
• Thyroid disorders