The investigators plan to explore the ability of amino acids, the building blocks of proteins in our bodies and in the food we eat, to stimulate muscles to grow and stay strong. The investigators will investigate how rapidly after one meal the human body is ready to make use of a second meal and look at the molecular mechanisms underlying this. The investigators will look at these phenomena in older men as this group is known to be subject to a gradual loss of muscle mass and strength.

Muscles can stay very constant in size for much of adult life yet dramatic wasting is seen in advanced age and ill health. A better understanding of how muscles regulate their size will help design treatments to slow wasting in disease and to promote active aging. We plan to study a group of older men, ~70yrs, the age at which muscle bulk starts to decrease, to observe how the muscles respond to feeding. We will provide a drink that contains the digested products of proteins from which muscles are built. Taking blood samples and some tiny biopsies of muscle (done under local anaesthesia) will allow us to measure muscle turnover and we will be able to measure for how long after a meal muscles actively take in nutrients before becoming "full". We will also measure how long the muscle remains "full" before it returns to a state where it can again be stimulated to take in nutrients. We will also explore if leucine, one of the component parts of protein (especially in meat and dairy products) and a food widely used supplement, can promote the early re-stimulation of muscle by eating.

Inclusion Criteria:

• Male
• 65-75yrs
• BMI 18-28

Exclusion Criteria:

• Type 2 Diabetes mellitus
• Neurological Disease
• Significant cardiac, hepatic or renal disease
• Active malignancy
• Medication inc. Corticosteroids, NSAID use, Beta adrenoblockers.