Leucine
Leucine and branched-chain amino acids (BCAAs) have been found to promote protein synthesis and increase muscle growth. BCAAs are also responsible for reducing fatigue during exercise. They are one of the building blocks of protein and can be used as supplements, as individual amino acids, or as a concoction of amino acid mixtures. In addition to promoting protein synthesis, leucine is believed to act as a signaling molecule. This may be why leucine is associated with appetite suppression.
A number of studies have investigated the role of leucine and branched chain amino acids in appetite. Several animal studies have shown that the amino acids can modify the secretion of leptin and food intake. These studies have been conducted using rats and mice. Moreover, human studies have been done in both healthy males and overweight subjects. The results have revealed that leucine has positive effects on the level of CCK, as well as the amount of food consumed.
Amino acids are important for triggering the mTOR pathway, which is responsible for boosting the anabolic state. However, the role of amino acids in controlling food consumption and their potential interactions with other nutrients is not fully understood. To address these questions, future research should determine the role of BCAAs in appetite control and the mechanisms by which they interact with other nutrients. It is likely that leucine and other amino acids can trigger the mTOR pathway and stimulate muscle protein synthesis. If this is the case, then increasing protein intake should have beneficial effects on appetite.
Studies have shown that leucine can reduce food intake and help improve fullness perception. In three of eight human trials, leucine supplementation resulted in a reduction in both total energy intake and the number of meals eaten per day. One study showed that a leucine-enriched bar reduced hunger and improved fullness. Another study demonstrated that the combination of BCAAs increased mRNA expression of Cck in proximal jejunum.
Some studies have been conducted on the effect of leucine on food intake in ob/ob and Wistar rats. Although the study did not show a significant difference between the control and the supplement groups, it did show that leucine treatment significantly reduced food intake in both types of rats. Furthermore, the effects of leucine supplementation were not observed in valine-treated mice.
Although studies have shown that leucine and branched-chain amino acid consumption can be helpful in lowering food intake and improving fullness, it is not clear how this effect will manifest itself in humans. As with many other amino acids, the effects of leucine and BCAAs on appetite may be influenced by the type of protein that is consumed.
Several studies have demonstrated that whey protein, which is the richest source of leucine, decreases food intake and hunger. Whey protein is believed to increase the secretion of GLP-1, which helps suppress food intake. Likewise, a study has shown that females with obesity and diabetes ate less and felt fuller after consuming a whey-rich meal. Finally, a study has shown that leucine infusion increased plasma GLP-1.
