Inclusion Criteria:  Aged 65-85 years Body mass index 18.5 - 30 kg/m2 Healthy Having given informed consent  Exclusion Criteria:  Allergy for one of the food items used >5% weight change in the previous 6 months Participating in a structured (progressive) exercise program, or in the past 3 months. Frequent (more than once per week) user of infrared (or traditional) sauna in the past 3 months Smoking Diagnosed with cardiovascular disease, kidney failure, rheumatoid arthritis Diagnosed musculoskeletal, GI tract, metabolic (e.g. diabetes) or pulmonary (e.g. COPD) disorders Use of any medications known to affect protein metabolism (i.e. corticosteroids, non-steroidal anti-inflammatories (NSAIDs). Chronic use of gastric acid suppressing medication and/ or anti-coagulants Recent (<1 year) participation in amino acid tracer (L-[ring-13C6]-phenylalanine and L-[3,5-2H2]-tyrosine) studies Blood donation in the past 2 months Strict Following a vegetarian diet Known allergic reaction to ultrasound contrast agent Non Dutch speaking