Download Leucine – Deemed the “Limiting Nutrient”

Leucine – Deemed the “Limiting Nutrient”
Leucine is a valuable tool in not only muscle building but can also play a critical role in weight
loss. It is an essential branched chain amino acid (BCAA), which means that it cannot be made
by the body and must be acquired through food or dietary supplements. Leucine has many
beneficial effects on the body, which includes boosting muscle anabolism, maintaining a
nitrogen balance, preserving muscle glycogen (which is glucose stored in muscle tissue used
to power muscle contraction), and preserving lean muscle tissue. Leucine also helps with
the regulation of blood-sugar levels, the growth and repair of muscle tissue (such as bones,
skin and muscles), growth hormone production, wound healing as well as energy regulation.
It can also assist to prevent the breakdown of muscle proteins that sometimes occur after
trauma or severe stress. Most surprisingly, leucine has been shown to actually prevent body
fat accumulation.
In a recent study at Columbia University, the investigators doubled the intake of leucine (via
leucine-enriched drinking water) in mice which were fed either a standard rodent chow or
a high-fat diet. While the higher leucine intake didn't produce major benefits in chow-fed
mice, it resulted in a 32% reduction of weight gain and a whopping 25% decrease in bodyfat mass in high-fat diet-fed mice. These results indicate that leucine is not a fat burner;
rather, it prevents body fat accumulation during overeating. But that wasn't all; leucine
supplementation also improved blood lipids and insulin sensitivity. Interestingly enough,
the reductions in total cholesterol and "bad cholesterol" (LDL) were largely independent
of leucine-induced changes in body-fat mass, suggesting that high leucine intake improves
cholesterol levels.
As the strongest of the BCAAs, Leucine is known as a “limiting nutrient”, which means that
you must have enough leucine in order for your body to make use of what you eat. If you
suffer from a leucine deficiency, your body will not be able to utilize the protein and amino
acids you consume.
To make sure you are getting the most out of the protein you are consuming, you need two
parts leucine and two parts valine for every one part of isoleucine.
Reference:
Zhang Y et al. Increasing dietary leucine intake reduces diet-induced obesity and improves glucose and cholesterol
metabolism in mice via multi-mechanisms. Diabetes, 2007 Jun;56(6):1647-54. Epub, 2007 Mar 14.
Becca Luna O’Connor, CPFT
Nutrition and Wellness Expert
Sports Nutrition Specialist