BCAAs and Body Composition

One of the many claims associated with BCAA supplementation is an improvement in body composition. BCAAs are supposed to help lower body fat percentage while also increasing muscle mass. While there is limited research on BCAAs and body composition, we can take a look at the available information to see if this claim holds up.

What does the research say on BCAAs’ ability to improve body composition?

Study 1: The effects of 8 weeks of heavy resistance training and branched-chain amino acid supplementation on body composition and muscle performance

The first study looked at whether BCAAs caused a decrease in body fat percentage when combined with heavy resistance training. Subjects were split into a supplement and placebo group. Both groups participated in eight weeks of resistance training, four times per week. The supplement group took nine grams of BCAAs on exercise days (half before, and half after exercising).

After eight weeks, results showed neither group increased total body weight or muscle mass. Additionally, neither group saw a decrease in body fat percentage. The researchers concluded that BCAAs had no effect on body composition.

Study 2: In a single-blind, matched group design: branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet

This study looked at the effects of BCAAs on athletes who were attempting to lose weight. The subjects were split into a supplement and carbohydrate group. The results showed the supplement group lost fat mass and maintained muscle mass. The carb group only lost muscle mass. The BCAA group also increased strength on the bench press while the carb group lost strength.

Limited Research on BCAAs and Body Composition

The research on whether BCAAs either decrease body fat or increase muscle mass is surprisingly limited. Beyond the two studies mentioned above, there is not much else on the topic. This makes coming to a solid conclusion difficult.

The Bottom Line – Do BCAAs improve body composition either through reducing body fat or increasing muscle mass?

In the first study, subjects taking BCAAs did not see any improvement. In the second study, subjects did lose body fat while maintaining muscle mass. Unfortunately, this study compared a BCAA supplement to a carbohydrate supplement making these results questionable in a practical setting.

Most athletes would take a protein supplement after a workout rather than only a carbohydrate supplement. Yes, compared to carbs, BCAAs may provide better body composition outcomes. The real question is, do BCAAs provide better results when compared to a protein supplement? The second study did not answer that question.

Do BCAAs improve body composition? It’s difficult to say. The evidence is lacking and the evidence that does exist does not support the claim.

References

  1. Spillane, M., & Emerson, C. (2012). The effects of 8 weeks of heavy resistance training and branched-chain amino acid supplementation on body composition and muscle performanceNutrition and Health, 21(4), 263-273. doi:10.1177/0260106013510999
  2. Dudgeon, W. D., & Kelley, E. P. (2016). In a single-blind, matched group design: Branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted dietJournal of the International Society of Sports Nutrition, 13(1). doi:10.1186/s12970-015-0112-9
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