You're actually right on the money... the amino acids will also help those 51 and over... L-Arginine, as a precursor to nitric oxide, which dilates blood vessels, has been shown to boost weight loss. It is also used in supplement formulations designed to increase libido... which can also lead to more burned calories...
"Arginine is an amino acid normally made by the body. Arginine is also found in many foods that have protein.
Arginine becomes nitric oxide (a blood vessel-widening agent called a vasodilator) in the body. Early evidence suggests that arginine may help treat medical conditions that improve with increased vasodilation. These conditions include chest pain, atherosclerosis (clogged arteries), heart disease, heart failure, erectile dysfunction, peripheral vascular disease, and headaches from blood vessel swelling).
Arginine also triggers the body to make protein and has been studied for healing wounds, bodybuilding, enhancing sperm production, and preventing tissue wasting in people with critical illnesses."
A study published online in the Journal of Dietary Supplements on January 10, 2014 concludes: "L-Arginine may be effective at reducing central adiposity in obese patients."
There are three conditions that have good evidence that arginine may help:
Heart disease: There is good scientific evidence that dietary supplementation with L-arginine may help people with coronary artery disease, angina, or clogged arteries, due to its effects on blood vessels. Larger, longer-term studies are needed to confirm these initial positive effects.
Heart failure: Arginine has been studied in people with heart failure. Longer-term studies are required to confirm the clinical benefit of L-arginine supplementation in people with heart disease.
Peripheral vascular disease/claudication: Peripheral vascular disease, also known as intermittent claudication, is a narrowing of blood vessels in the legs and feet caused by fatty deposits. This condition causes decreased blood flow to the legs and feet, resulting in leg pain and tiredness. A small number of studies report that arginine therapy may improve walking distance in people with claudication. Further research is needed.
There are 40 more conditions where treatment with arginine is still unclear and further research is warranted.
The Mayo Clinic is also studying how branched-chain amino acids (BCAA) may help with diabetes and aging in relation to mechanisms of muscle wasting and aging, and investigating the specific role of BCAAs as regulators of muscle protein expression and mitochondrial function in young and elderly people.