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The Science of BCAA Supplements

Exercise & Branched Chain Amino Acids:

Jade Teta ND CSCS & Keoni Teta ND, LAc, CSCS

Exercise is a key component of any weight loss program. Yet a major challenge of weight loss protocols is controlling the compensatory reactions that naturally occur with increased activity, namely increased hunger and cravings, created by the unique hormonal changes that occur during exercise (1-3).

Another confounding factor is maintaining muscle mass in those undergoing rigorous exercise regimes for weight loss. This is especially true when low carb or low calorie diets are combined with exercise (9). Because muscle mass determines 40% of an individual’s ability to handle insulin and approximately 80% of a person’s blood sugar use, muscle is perhaps one of the most valuable resource in weight loss protocols (5-6).

The branched chain amino acids (BCAA) may have special utilization in weight loss programs combining exercise with diet. BCAA supplementation has been shown to increase muscle mass (4,12), decrease hunger (13), regulate blood sugar (10,14), attenuate the stress hormone response of exercise (7), and may increase exercise capacity (4,11) and fat-burning (11) directly.

BCAA & muscle mass

The journal Obesity in 2008 showed resistance training is one tool to help maintain muscle mass when dieting (8). BCAA are another. Branched chain amino acids, most notably leucine, interact with the anabolic cell signaling messenger mTOR stimulating muscle growth alone and synergistically with resistance exercise (15).

This is an important consideration since studies have shown traditional weight loss approaches can impact muscle mass and decrease metabolic rate (BMR) by 10-20% (16). A slowed BMR is a predictor of yo-yo weight gain. Those with the largest metabolic declines induced by muscle loss are four times more likely to regain lost weight over the next 24 months (17).

BCAA controls hunger, cravings and energy

Perhaps the most important component of maintaining an exercise regime and diet plan is related to willpower. Due to the compensatory reactions created by excessive exercise and/or dietary restriction, it is almost impossible to win the battle of wills against the physiology. BCAA have special actions in regulating energy, controlling hunger, and potentially benefiting stress induced cravings.

BCAA effects on hunger, cravings and energy come from the ability of these aminos to generate the gluconeogenic precursors glutamine and alanine. This has a balancing effect on blood sugar. A March 2011 study by Gualano, et al. showed 3 days of supplementation with high doses of BCAA resulted in increased fat oxidation and exercise performance in response to glycogen depletion compared to a placebo. This was likely due to the ability of the BCAA supplements to maintain glycemic control as stated by the researchers: “Importantly, our findings suggest that BCAA supplementation appears to prevent the exercise-induced hypoglycemia, particularly in glycogen depleted subjects.”

Obviously the ability to maintain blood sugar balance in low calorie or low carb dieters will indirectly impact hunger, but exercise has direct hunger inducing effect (2). BCAA supplements have been shown to impact hunger directly and may provide a buffer to exercise’s appetite stimulation. Both AMP-activated protein kinase (AMPK) and mTOR signaling have hunger suppressing effects in the hypothalamus. Leucine has been shown to adjust both signaling systems and reduce food intake (13).

The effect on cravings is more indirect than BCAA’s impact on hunger. The blood sugar balancing activity of BCAA would likely have an impact on decreasing cravings, but stress hormones may be involved as well. Excessive exercise and the stress of dieting may raise stress hormones (18). The stress hormone cortisol has been implicated in brain chemistry changes that induce cravings specifically for highly palatable foods (salt, sugar, starch, fat) (3). BCAA supplementation lowers the cortisol elevation often seen with intense and prolonged exercise (7).

BCAA and fat loss

A February 2011 population study out of The Journal of Nutrition by Qin et al, looked at a cohort of 4,429 subjects from Japan, UK, USA, and China (19). There was a positive correlation for escalating intake of BCAA and reduced risk of being overweight or obese.

A January 1997 article on competitive wrestlers shows the impact of BCAA on weight loss and exercise performance (20). Competitive wrestlers are a good model for the study of calorie/carb restrictive diets combined with intense exercise regimes. Twenty-five competitive wrestlers were randomized to 4 different low calorie dies: Low calorie & low protein, low calorie control, low calorie high protein, and low calorie & BCAA supplementation. The BCAA group lost the greatest amount of weight (9 pounds), body fat (loss of 17%), and specifically lost weight from visceral adipose tissue (a reduction of 34%).

Finally, a pilot study out of the journal AGE showed a dose of 12g BCAA in combination with oleic acid and DHA resulted in a close to 4 pound weight loss with in a period of only 2 weeks in women over the age of 38 (21). The researchers chose the BCAA leucine because of its effects on hunger and fat loss in other studies. “In conclusion, this study demonstrates that leucine……… may cause weight loss through signaling mechanisms to the brain and adipose tissue.”

Clinical implications

The dose of BCAA supplements used in studies range from 5 to 15g daily and higher (22). Some studies on appetite suppressing effects suggest higher doses of 300mg/kg body weight. Most information suggests a 3:1:1 ratio of leucine to valine to isoleucine.

Given the potential for negative compensatory reactions during weight loss exercise protocols, interventions that are able to maintain muscle mass and control hunger, energy and cravings are needed. Branched chain amino acids (BCAA) have many overlapping mechanisms that may help weight loss efforts through exercise and dieting.


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