Peri-Workout BCAA + Glutamine + Citrulline Consumption Blunts Muscle & Fat Loss Compared to Powerade Placebo

"Shed the fat, keep the muscle!" That's a promise you will find not literally, but analogously in every ad for BCAAs, but do they actually do that? Help you shed fat and retain muscle? Scientific prove to support this claim is, as of yet, missing.

With BCAAs it is just as it is with 99.9% of the supplements: Ads and product labels are full of scientifically unproven claims. One of these unproven claims is that the consumption of branched-chain amino acids would protect you from losing muscle while you're dieting ... the problem with this notion is - as sound as it may seem in view of the mTOR promoting effects of leucine, there's no study which would prove that guzzling BCAAs all day will in promote fat and blunt lean mass losses when you're cutting.... or I should say "as of now, there was no study...", right? After all, there's this new study by Dudgeon et al.'s the abstract of which tells us that "BCAA supplementation in trained individuals performing resistance training while on a hypocaloric diet can maintain lean mass and preserve skeletal muscle performance while losing fat mass" (Dudgeon. 2015).
As we are going to see after taking a look at the design and results of Dudgeon's single-blind study in seventeen resistance-trained males (21–28 years of age) on hypocaloric diets, this is yet a potentially misleading conclusion. Not because it was wrong, but rather because it omits an observation that could be of paramount importance to dieters who have the free choice between the two treatments, the subjects of the study were randomly assigned to, namely...

• 14g of Xtend (BCAA) before after workouts or
• 14 g Powerade (CHO) before and after workouts

The supplements were consumed for a total study time of 8 weeks during which all subjects trained four times per week according to a standardized workout program and consumed a diet that was programmed (but not controlled) to contain roughly 35% less energy than the subjects required on workout days and approximately 10% less energy than required on off-days.
Now you may be rightly asking yourselves why I am so vague with respect to the energy deficit. Well, everything we learn from the full text of the study is that all subjects were "provided an individualized caloric restricted diet based on individual data (body mass, body composition, resting metabolic rate, etc.)" (Dudgeon. 2015) - a diet the scientists describe as follows:

Table 1: W/ the Harris-Benedict equation you calculate the basal metabolic rate and multiply it with a factor (multiplier) that describes your activity level best to arrive at the "real" estimated energy requirements.

"The caloric-restricted diet was designed as an 8 week “cut diet” for reducing body fat, and used a modified carbohydrate-restricted diet approach (percent of total calories for workout days were 30 % carbohydrates, 35 % protein and 35 % fat and for off days were 25 % carbohydrates, 40 % protein and 35 % fat). Each individual’s daily caloric and macronutrient intake was determined using the Harris Benedict formula with an activity factor of 1.35 (lightly active individual engaging in light exercise 1–3 days/week) for workout days and 1.125 (sedentary individual) for off days" (Dudgeon. 2015).

Since the Harris-Benedict formula is only a really rough estimate of how much energy you actually need, my previous estimations of the energy deficit are as "accurate" as I can possibly be. The 1604kcal that are printed in red bold letters on top of the exemplary meal plan in Figure 2, however, suggest that the deficit on the off days was significantly larger. After all, the subjects' mean weight was >80kg and their daily energy requirements should thus be at least 2,000kcal - even on off days (and the table in which the macronutrient composition is listed actually says that the mean intake was 2046 and 2264kcal/day for the BCAA and CHO group respectively).

Table 2: Sample dietary card for a subject during an off, non-workout, day (Dudgeon. 2015).

In view of the fact that the response I got from the authors to an email in which I asked about the exact kcal deficit only referred me to the previously cited passage about the activity factors, I guess it is futile to further speculate about the energy deficit, of which I would still like to add that it was probably higher in the heavier and taller BCAA group. Why? Well, the BCAA group had plans with 2456 and 2046 kcal on workout and off days, the CHO group on the other hand were fed 2717 and 2264 kcal... Whatever, let's get to the more relevant, but not less confusing changes in body weight, lean mass and fat mass the researchers report for the BCAA and CHO groups:

Figure 1: Pre and post absolute mean body weight, body fat and lean body mass values before and after the 8-week intervention; * p < 0.05 for the difference within groups (no difference between groups | Dudgeon. 2015)

-0.1 kg and -2.3 kg of body weight, +0.4 kg and -0.9 kg of lean mass and 0.6 kg and 1.4 kg fat mass in the BCAA and CHO groups respectively - that's in line with the previously cited conclusion. The BCAA supplement blunted the small loss of lean mass in the CHO group, but if we look at the complete dataset, a somewhat different image emerges; one in which the two classic markers of body composition, namely the relative amount of body fat (aka "body fat percentage") and the lean mass as percentage of the total mass changed in a way that favors CHO over BCAA supplements:

Figure 2: Pre vs. post values for body fat % and lean mass %, the two parameters you would classically use to assess body composition (instead of absolute lean and fat mass); pre-to-post change on top of the post-bars (Dudgeon. 2015).

Now, I am not saying that the consumption of the BCAA (+citrulline + glutamine) supplement did not blunt the loss of lean mass - it obviously did. What I want you to keep in mind, though, is the fact that the consumption of 14g of BCAAs before and after workouts appears to suffocated any dieting efforts - after all, the subjects lost a practically irrelevant (and for whatever reason allegedly statistical significant) amount of 600g body fat; that's in contrast to the 1.4 kg of fat mass the subjects in the control group lost; and that's a practically relevant insight, even if this fat loss was allegedly statistically non-significant, because  it implies that BCAAs practically blunt fat loss.
References:

• Dudgeon, WD; Page Kelly, E; Scheett TP. "In a single-blind, matched group design: branched-chain amino acid supplementation and resistance training maintains lean body mass during a caloric restricted diet." Journal of the International Society of Sports Nutrition  (2016) 13:1.
• Faure, Cécile, et al. "Leucine and citrulline modulate muscle function in malnourished aged rats." Amino acids 42.4 (2012): 1425-1433.
• Moinard, Christophe, and Luc Cynober. "Citrulline: a new player in the control of nitrogen homeostasis." The Journal of nutrition 137.6 (2007): 1621S-1625S.
• Hickson, R. C., S. M. Czerwinski, and L. E. Wegrzyn. "Glutamine prevents downregulation of myosin heavy chain synthesis and muscle atrophy from glucocorticoids." American Journal of Physiology-Endocrinology and Metabolism 268.4 (1995): E730-E734.
• Hickson, Robert C., et al. "Protective effect of glutamine from glucocorticoid-induced muscle atrophy occurs without alterations in circulating insulin-like growth factor (IGF)-I and IGF-binding protein levels." Experimental Biology and Medicine 216.1 (1997): 65-71.
• Salehian, Behrouz, et al. "The effect of glutamine on prevention of glucocorticoid-induced skeletal muscle atrophy is associated with myostatin suppression." Metabolism 55.9 (2006): 1239-1247.
• Ventura, G., et al. "Effect of citrulline on muscle functions during moderate dietary restriction in healthy adult rats." Amino acids 45.5 (2013): 1123-1131.