Glucocorticoid Long-term Administration: Effect on Cold Induced Energy Expenditure and Resting Metabolic Rate

Inclusion Criteria: * Planned therapy with at least 7.5 mg prednisone equivalent per day or higher for more than 28 days (group A) * Planned weaning off glucocorticoid therapy which lasted al least 28 days with a dosage of at least 7.5 mg prednisone (group B) * BMI 19-30 kg/m2 * Informed Consent as documented by signature Exclusion Criteria: * Insufficient thyroid hormone substitution in case of hypothyroidism * Uncontrolled diabetes mellitus (HbA1c \>7.5%) * Severe concomitant diseases: chronic heart failure, liver cirrhosis, kidney failure, active cancer * Known hypersensitivity to cold, e.g. primary or secondary Raynaud's Syndrome * Known or suspected non-compliance * Abuse of alcohol or illicit drugs * Claustrophobia * Women who are pregnant or breast feeding * Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc of the participant * Previous enrolment into the current study * Enrolment into another study using ionizing radiation within the previous 12 months