From Ergo Log
Supplementation with the amino acid L-citrulline can reduce the amount of abdominal fat. Molecular researchers at the Universite Paris Descartes will soon publish an article on this in Molecular Nutrition and Food Research. If the French researchers have got the right end of the stick, then L-citrulline may help people with an apple-shaped body to acquire a pear-shaped body.
If you tend to put on fat in the abdominal area you're doubly unlucky. Belly fat or, as physiologists prefer to call it, visceral fat, increases the chance of heart attacks and diabetes, and it's a disaster for your figure too: 'apples' are regarded as less attractive than 'pears'.
Whether you're an 'apple' or a 'pear' depends on your hormonal balance, and also your age. The older you are, the more easily you accumulate fat in your abdominal cavity. The French researchers wondered whether L-citrulline could reduce age-associated abdominal fat deposition. Researchers who had given older lab animals L-citrulline had sometimes reported this effect. [J Nutr. 2007 Dec;137(12):2680-5.]
L-Citrulline & Fat
The researchers gave young and old rats a hefty dose of L-citrulline daily for three months. At the end of the experimental period the researchers examined samples of visceral fat tissue from the animals, and compared these with tissue from rats of the same age that had not been given L-citrulline.
In the old rats L-citrulline boosted the secretion of free fatty acids [NEFA] and glycerol from the visceral fat cells. That means that the visceral fat cells release their contents more easily into the bloodstream so that the body can burn them.
At the same time L-citrulline reduced the speed with which the visceral fat cells stores nutrients as fat. The amino acid reduced the flux and reduced the effect of the enzyme cytosolic phosphoenolpyruvate carboxykinase or PEPCK-C. This probably happened as a result of L-citrulline sabotaging the functioning of the fat sensor PPAR-gamma in the visceral fat cells.
The inhibition of growth processes in visceral fat cells also took place in the young rats.
"This metabolic action of L-citrulline in the young rat could be a mechanism to limit lipid storage and to facilitate fat burning", the researchers write. "In advanced age, fat depots are redistributed, leading to an increased ratio of visceral to subcutaneous fat mass. The L-citrulline-induced reduction of fat deposit in visceral adipose tissue could prevent this increase in ratio of visceral to subcutaneous fat, and hence limit the associated pathological risks (e.g. diabetes, cardiovascular diseases) related to aging."
"In obesity, the rise in adipose tissue mass also affects predominantly visceral fat, and L-citrulline effects in this pathophysiological situation remain an open question."
Mol Nutr Food Res. 2014 Jun 10. doi: 10.1002/mnfr.201400053. [Epub ahead of print].