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L-Arginine Reduces Fat and Waist Circumference

Researchers, writing in the November 2006 American Journal of Physiology, Endocrinology and Metabolism published a study demonstrating the weight-loss benefits of high doses of the amino acid L-Arginine.

Thirty three obese patients with elevated blood sugar consumed a low-calorie diet and exercised for 21 days. Subjects were then divided into two groups. The first group received 8.3 grams a day of L-arginine; the second group received placebo.

At the end of the study, those who took L-arginine had a statistically significant decrease in adipose fat mass and waist circumference, with statistically significant improvements in mean daily glucose profiles.

Study authors indicated that long-term oral L-arginine supplementation resulted in an additive effect, compared with the diet and exercise program alone. Researchers further noted that arginine improved function within the lining of artery walls and reduced oxidative stress in obese patients with elevated blood sugar and insulin resistance.


Because chronic L-arginine supplementation improves insulin sensitivity and endothelial function in nonobese type 2 diabetic patients, the aim of this study was to evaluate the effects of a long-term oral L-arginine therapy on adipose fat mass (FM) and muscle free-fat mass (FFM) distribution, daily glucose levels, insulin sensitivity, endothelial function, oxidative stress, and adipokine release in obese type 2 diabetic patients with insulin resistance who were treated with a combined period of hypocaloric diet and exercise training.

Thirty-three type 2 diabetic patients participated in a hypocaloric diet plus an exercise training program for 21 days. Furthermore, they were divided into two groups in randomized order: the first group was also treated with L-arginine (8.3 g/day), and the second group was treated with placebo.

Although in the placebo group body weight, waist circumference, daily glucose profiles, fructosamine, insulin, and homeostasis model assessment index significantly decreased, L-arginine supplementation further decreased FM (P < 0.05) and waist circumference (P < 0.0001), preserving FFM (P < 0.03), and improved mean daily glucose profiles (P < 0.0001) and fructosamine (P < 0.03). Moreover, change in area under the curve of cGMP (second messenger of nitric oxide; P < 0.001), superoxide dismutase (index of antioxidant capacity; P < 0.01), and adiponectin levels (P < 0.02) increased, whereas basal endothelin-1 levels (P < 0.01) and leptin-to-adiponectin ratio (P < 0.05) decreased in the L-arginine group.

Long-term oral L-arginine treatment resulted in an additive effect compared with a diet and exercise training program alone on glucose metabolism and insulin sensitivity. Furthermore, it improved endothelial function, oxidative stress, and adipokine release in obese type 2 diabetic patients with insulin resistance.


Lucotti P, Setola E, Monti L, Galluccio E, et. al. Beneficial effects of a long-term oral L-arginine treatment added to a hypocaloric diet and exercise training program in obese, insulin-resistant type 2 diabetic patients. Am J Physiol Endocrinol Metab 291: E906-E912, 2006 Nov.

Key concepts: weight-loss, l-arginine