I found an article which shed a little light on the relationship between l-glutamine, cravings and weight loss. But only a little, mind you.

From The March 1997 Issue of Nutrition Science News - Glutamine And Human Performance
http://www.healthwellexchange.com/n...ine.cfm?path=ex

Insulin Resistance
Supplemental glutamine was recently shown to reduce body weight and prevent high blood sugar and high insulin levels in mice fed a high-fat diet.6 The mice were genetically predisposed to become overweight and develop high blood-sugar levels when consuming a high-fat diet, but these unhealthy outcomes were essentially neutralized for the mice that had glutamine added to their food.

Increases in body fat and body weight and high blood sugar are thought to result from persistently high levels of insulin in the blood, a condition known as insulin resistance (see NSN, March 1996, for an article on insulin resistance). Insulin levels skyrocketed in the mice fed a high-fat diet without supplemental glutamine, while those fed the glutamine-supplemented diet showed normal insulin patterns.

Although this is only an animal trial, the potential ability of glutamine supplements to reduce insulin resistance is exciting. Insulin resistance is now estimated to occur in half of all obese people and is considered a major risk factor for heart disease, high blood pressure and diabetes. While it is premature to jump from animal studies to conclusions about humans, the research so far may suggest a safe, nutritional way to adjust metabolism and look and feel healthy.

Mental Energy
Glutamine and other amino acids such as choline, tyrosine and phenylalanine are used by the brain and central nervous system (CNS) to make neurotransmitters--biochemical mediators that stimulate or reduce the brain's electrical impulses that translate into thoughts, sensations and emotions. Different neurotransmitters can also influence perceptions of energy or fatigue. Neurotransmitters appear to get metabolized, or "used up," as a normal part of body function. Heavy mental or physical stress may cause the CNS to metabolize more neurotransmitters, so whether depletion is caused by intensive concentration, a demanding job or exercise, full replenishment of these essential biochemicals is vital to keep the brain "tuned up."

Neurotransmitter production is thought to increase when the amino acids they are formed from are supplemented in the diet. If this is true for glutamine, nutritional strategies that replenish it may also boost perception of energy or help prevent mental fatigue.

Two final points are important for the glutamine story. First, too much glutamine may be counterproductive. In humans, more than two grams is likely to result in less growth hormone production, less bicarbonate buffer, and probably no further energy benefit. In fact, elevated doses may overstimulate brain neurotransmitters and be dangerous. So, while some glutamine may be beneficial, large amounts may be a waste of money and even harmful.

Secondly, most of the glutamine studies appearing in scientific journals are conducted with isolated cells or animals. More human clinical research is needed to fill in missing pieces of the glutamine puzzle. Nonetheless, glutamine's emerging picture is exciting and cause for optimism. It may become an essential supplement for consumers in years to come.

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