Does Creatine Blunt Fat Loss? A Recent Study Supports Long-Standing Suspicions, But What Are the Implications?

Better  lean than strong? Why not both?
Anyone remember the allegedly not very popular post on the "anti-creatine" β-Guanidinopropionic Acid (GPA) and it's ability to increase AMPK, decreases blood glucose & insulin, induce weight loss without dieting, increase skeletal muscle oxidative capacity and delay the development of mammary cancer (read up on the news)? I thought so...

Even I had was just about to forget about it, when I stumbled upon a recently published Brazilian study which found that the "real" - not the anti-creatine - does in fact what you would expect from the "evil twin" of GPA: It blunts the exercise induced fat loss in highly trained amateur athletes (Manjarrez-Montes de Oca. 2013).

"What!? Creatine makes me fat?"

Now, before you start freaking out, let me say this: There are also studies which suggest that creatine supplementation does the exact opposite, i.e. that it can (combined with an intense exercise protocol) decrease body fat level (van Loon. 2003; Volek. 2004). If you dig deeper, you will yet find that most studies actually don't report any changes in the ratio of fat to total body mass most of you know as "body fat percentage" (Kreider. 1998; Volek. 1999; Becque. 2000).

Whatever the results of the individual experiments may be, in the end only studies like the one done by Jeff Volek et al. at the University of Connecticut or the study at hand, i.e. studies in the course of which the scientists actually measure/d the total amount of lean and fat mass can provide an adequate idea of what exactly supplemental creatine can do for our physiques. If the data includes only body fat percentages, maybe even measured with bio-impedance (→ yesterday's Facebook news on "losing" 1.4% of body fat in a single session), this does not suffice to say, whether the absolute amount of body fat changed. Or in other words, whether any observed increase / decrease in body fat (%) was simply a result of the fact that the ratio of lean to total body mass increased faster than the rate of fat to total body mass, wile the subjects abs still disappeared under a nasty layer of blubber.
Figure 1: Changes in body mass, bone free lean mass, fat mass and body fat percentage (left), as well as individual "fat gain" response to creatine supplementation in the 14 subjects (Manjarrez-Montes de Oca. 2013).
The study at hand is in fact a perfect example for the way body fat  levels alone can fool you. A brief glance at the data in figure 1 confirms that. While the body fat percentage says that the 12 non-smoking, non-vegetarian, red and black belt male recreational taekwandoo players must effectively have lost weight in the creatine phase of this, the total fat mass reveals that adding 50mg/kg creatine to their sports drink (30 g of sucrose, artificial flavor, 500ml) lead to an increase, the addition of the same amount of maltodextrin to a decrease in DEXA measured total body fat.

If it were not for the results of of 2002 paper by Huso, I guess, I would just tell you to simply forget about the hoopla and discard the notion that creatine would have any effect on body fat levels, at all (Huso. 2002). Huso et al. had investigated the influence of creatine supplementation (20 g/day for 4 days, then 2 g/day for 17 days) on substrate utilization during rest using a double-blind crossover design. To this ends the researchers recruited 10 active men who participated in a 12 wk resistance training protocol (3x /week full body resistance training; 3 sets, 10 reps) involving a placebo and a creatine trial that were separated by a 4-wk washout.
Figure 2: Changes in body composition (body mass, body fat and fat free mass) and 1RM strength on the bench press and leg press in the 12-week double-blind randomized cross over trial by Huso et al. (Huso. 2002)
Very similar to Manjarrez-Montes de Oca et al. in the study at hand,  Huso et al. observed a significant decrease in fat mass (-2.4kg) in the placebo trial, while there were no significant changes in either of the two parameters, when the subjects were "on creatine".

So how come that creatine does even have the ability to inhibit fat loss?

Just like the identical change in lean mass (in fact, only the strength increase speaks in favor of the creatine loading + maintenance regimen) the inhibition of the fat loss in the trial of the Huso study was actually only a "side finding". Originally, Huso et al. had set out to elucidate, whether the "anecdotal evidence of weight gain, including a lack of fat loss, in persons taking creatine" (Huso. 2002) could be brought about by creatine induced increases / decreases of the respiratory exchange ratio (RER = the ratio of carbohydrates to fats that are oxidized during a workout). And while the scientists state in their abstract that the "[c]hanges in substrate oxidation" they observed "may influence the inhibition of fat mass loss associated with creatine after weight training" (Huso. 2002), it is at least in my humble opinion not very likely that the small statistically only borderline significant shift from fat to carbohydrate oxidation (+/- 9%, respectively) alone can actually explain the >2kg difference in total fat mass loss. Still, this is exactly what Manjarrez-Montes de Oca et al. feel would be the most likely explanation for the observations they made 11 years later, as well:
I wonder if Usain Bolt consumes creatine supplements. Or is he on GPA, click here to learn what would be more likely.
"It has been suggested that the increase in carbohydrate utilization induced by Cr may be due to an activation of the enzyme phosphofructokinase, which produce an increase in glucose utilization, with elevation of malonyl-CoA and inhibition of carnitine palmitoyltransferase 1 (CPT1) system, which transports fatty acids into the mitochondria for oxidation (Huso. 2002).

If fatty acids are not transported into the mitochondria of skeletal muscle cells to be oxidized, they could be expected to be maintained in blood as triglycerides; and then stored in the adipose tissue.

We observed a higher concentration of triglycerides after Cr supplementation, and also found that subjects after Cr treatment gained fat mass whereas after placebo treatment fat was lost. Therefore, both findings could imply that fatty acid mitochondrial uptake has been inhibited by Cr ingestion, altering the normal fat loss produced by TKD training."
What you should keep in mind though, is that the dietary intake was not controlled for (what if increased glucose oxidation simply made the subjects hungrier?). In calorically restricted scenario the results could thus have been very different, so that it is overall not very likely that creatine would ruin your dieting efforts. Moreover, there is some, allegedly not very conclusive evidence that the addition of a reasonable amount of creatine to your diet could actually help you spare muscle tissue. The fact that the placebo-specific increase in protein oxidation from 11.6% to 15.3% was just as absent in the creatine group as the fat loss, is however hardly a convincing, let alone bullet-proof argument in favor of creatine as a dieting aid. After all the protein oxidation in the creatine group remained stable on the same high levels of roughly 15%.

Bottom line: I don't feel that the evidence "against" taking reasonable amounts of creatine (2-3g per day) is conclusive enough to panic and give up on the possible beneficial effects on lean mass (Nissen. 2003; Poortmans. 2010). Still, if you really have good reason to believe that creatine may blunt your fat loss (it's not impossible, take a look at the "high responders" in figure 1, right), I don't see why you could not give it a try and simply stop taking your creatine for a months or so. If after an initial flattening effect you don't see any other changes in your physique you are at least sure that you don't belong to the unlucky few, for whom creatine monohydrate (not one of the sugar-laden combi products!) could maybe and due to whatever interaction of genes, diet and whatever other confounding factors, forestall fat loss.

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