Prandial Metabolic Phenotype in Adults

The study involves 1 screening visits of approximately 3 hours and 6 study days of approximately 8 hours.

Subjects will be asked to arrive in the fasted state on all study days. Fasting prior to screening is not required. On the screening day, body weight, height, and body composition by Dual-energy X-ray absorptiometry (DXA) will be measured. In addition, The Six-Minute Walk Test (6MWT) and skeletal muscle function tests will be assessed at the end of each screening visit.

Each study visit will begin with vital signs. Before administration of the feeding or the tracer solution, baseline blood will be collected for measurement of the natural enrichment of metabolites. After the baseline sample is collected, feeding will begin and will be followed by tracers of several compounds that may be administered by IV pulse.

Next, the subjects will be fed one of six liquid nutritional supplement every 20 minutes for 6 hours. The liquid nutrition supplement will target the amino acid formulation in the following meals (1) total amino acid, (2) Essential Amino Acids (EAA), (3) EAA + -hydroxy -methylbutyric acid (HMB), (4) EAA + leucine (LEU), (5) EAA high, and (6) Placebo.

Inclusion criteria

• Age: 60-80, inclusive
• Stable body-weight (± 5%) for the past 3 months
• Subject is judged to be in satisfactory health based on medical history, physical examination, and laboratory screening evaluations.
• Ability to walk, sit down and stand up independently or with walking mobility aids
• Ability to lie in supine or elevated position for up to 7 hours
• Willingness and ability to comply with the protocol

Exclusion criteria

• Established diagnosis of current malignancy
• History of untreated metabolic diseases including hepatic or renal disorder
• Presence of acute illness or metabolically unstable chronic illness
• Presence of fever within the last 3 days
• Use of short course of oral corticosteroids within 4 weeks preceding study day
• (Possible) pregnancy
• Failure to give informed consent or Investigator's uncertainty about the willingness or ability of the subject to comply with the protocol requirements
• Already enrolled in another clinical trial and that clinical trial interferes with participating in this study
• Any other condition according to the PI or nurse that was found during the screening visit, that would interfere with the study or safety of the patient