Creatine and fluid retention

Geschatte leestijd: 8 minuten Creatine causes water retention. At least, is that really the case? And where does that water actually go? Opinions on where that water stays in your body vary widely. Some say it makes you blow up and get a puffy face, while others say it goes into your muscles, making you look fuller. Moreover, it also depends on which type of creatine you supplement. Some types are said to make you retain water while others do not.   In this article, I will explain what science has to say about this. First, I will tell you about the most likely mechanism responsible for water retention. Then, I will discuss three studies, each of which used a different measurement method to tell us where that water stays in our bodies. Finally, I will address how different types of creatine may influence this.

Creatine and water retention: the mechanism

We are not exactly sure how creatine causes water retention. However, there is a strong suspicion that it is due to a process called osmosis. If you, like me, have finished high school, you have probably heard of this term before. But, like most people, you may not remember exactly what it means. So, here’s a brief refresher. When you have two solutions of water, such as salt solutions, and these solutions are separated by a barrier that allows water to pass through but not salt, osmosis can occur. I’ll spare you the clever physics behind this. What’s important is that osmosis involves net movement of water from a dilute solution to a concentrated solution. In this example, if one salt solution contains 1% salt (the dilute solution) and the other contains 2% salt (the concentrated solution), water will flow net into the concentrated solution until the “osmotic pressure” is balanced. You also need to consider the osmotic pressure that can arise from the fluids, but you can ignore that for now. Now, the same thing happens with your muscle cells. The cell membrane acts as the ‘barrier’ that allows water to pass through but only lets creatine through in one direction: inward. So, let’s say your muscle cells are initially in perfect osmotic balance. There is no net movement of water into or out of the muscle cells. Then, you start supplementing with creatine. The creatine is taken up by your muscle cells, increasing their concentration. This creates an osmotic pressure, causing net water to flow into the muscle cells until the osmotic pressure is balanced. That’s all. This is the most likely mechanism by which creatine retains water. The increased storage of creatine in the muscle cells, through osmosis, causes the cells to ‘pull in’ and retain some extra water. Research also shows that a creatine loading phase leads to a rapid increase in body weight of about 1 kilogram [1]. The period is too short to assume an increase in dry muscle mass, so it is assumed to be water weight.

Where does the water from creatine go? Measurements are key.

In the literature, I found three studies that looked at the distribution of body fluids of subjects before and after creatine supplementation. Each of these studies used a different measurement method, and the results – probably partly because of this – do not align. Below, I will discuss these studies one by one. For each study, I will provide a brief explanation of the measurement method used and give you the results found.

The water goes into the cells according to multifrequency bio-impedance analysis

The first study I want to discuss used multifrequency bio-impedance analysis, or MFBIA. I’ll explain this method a bit further because you may have used it yourself. Bio-impedance analysis is commonly used in gyms to determine body composition. Often, there are scales that can tell you your fat-free mass and fat mass when you step on them and enter your weight, height, age, and gender into the device. Sometimes, devices that you hold with your hands in front of your body are used, which work on the same principle as the scales. The name of bio-impedance analysis gives a hint as to how it works. It measures impedance, which is a fancy word for how much resistance an alternating current experiences and how much it is delayed. When you stand barefoot on such a scale, a tiny current is sent through both feet simultaneously, and the current is also detected at both feet simultaneously. This allows it to determine the impedance of your lower body. Fatty tissue has a very high impedance, and watery tissues like muscle have a much lower impedance. So, if you’re carrying more fat, the impedance is higher than if you’re leaner. By then putting the measured impedance into a formula along with the data you entered, an estimate can be made of the total amount of water in your body, and thus the amount of fat mass and fat-free mass. Those calculations are done automatically by those scales and devices for you.

Disadvantages of bio-impedance analysis

However, there are quite a few caveats to this method. The hydration status of the person is very important. If you have just drunk a lot, the impedance decreases, and consequently, a lower body fat percentage is measured. The opposite applies to someone who is dehydrated. Other factors that influence it include how well your skin conducts the current at the electrode site (your feet in the case of the scale). Your skin must be clean and dry. But also things like your body posture and how the fluid is distributed in your body at that moment play a role .

MFBIA can measure fluid both inside and outside the cells

With MFBIA, not just one current is sent through your body, but several. These differ in their frequency, and this affects which part of your body they conduct through. A current with a low frequency does not pass through the cell membranes and is therefore conducted only by the fluid outside the cells (extracellular fluid). A current with a high frequency does pass through, and thus is also conducted by the fluid inside the cells (intracellular fluid). By combining those measurements, you can approximately determine how much fluid is inside and outside the cells.

Results of the study by Ziegenfuss et al.

Ziegenfuss et al. applied this method to see where the water from creatine supplementation goes [2]. They gave subjects 0.07 grams of creatine per kg of fat-free mass (about 21 grams for the average Joe) per day for three days. The MFBIA measurements showed a significant increase of 3% in intracellular fluid and no change in extracellular fluid. A weakness of the study is that there was no placebo group. So, it’s hard to say whether the found result was actually due to creatine supplementation, although this seems likely. In conclusion, you could say that the water from creatine supplementation ends up in the cells, making you appear fuller.

The water stays in the cells according to magnetic resonance technique

A few years after the results of Ziegenfuss et al., a group of researchers investigated where the water from creatine went using a different technique. They did this using magnetic resonance (MR) technique. This technique exploits a certain property of protons, which, depending on the tissue and fluid compartment they are in, show a different relaxation time. This difference allows one to determine fairly accurately how much fluid is present at the measured location within and outside the cells.

Results of the study by Saab et al.

Saab et al. applied this technique and gave subjects a placebo or 20 grams of creatine per day for five days. However, the technique is applied locally: the subjects were not put into such a giant MRI scanner as you see in hospitals. A small scanner was used to examine the effect of creatine supplementation on fluid balance in the flexor digitorum profundus: one of the muscles that bend your fingers. (Yes, that’s where the creatine you take ends up too.) What the authors found was that the group receiving creatine supplementation showed a significant increase in intracellular compartment fluid. This result is in line with the aforementioned results found with MFBIA.

The water comes both inside and outside the cells according to isotope dilution analysis

The last study I want to discuss used isotope dilution analysis. This is a rather sophisticated technique that can be considered the gold standard for mapping body fluids. Like the word osmosis, you’ve probably heard the word isotope in high school. Or not, no worries, I’ll explain. Isotopes are elements, such as carbon, hydrogen, nitrogen, etc., that behave exactly like their ‘normal’ counterpart but have a different weight. To explain that further: let’s say you have a hydrogen atom. It consists of one electron and one proton. An isotope of this, called deuterium, contains, in addition to this electron and proton, one neutron, making deuterium heavier. Due to that difference in weight, you can distinguish isotopes from the normal elements floating around in your body. Take, for example, so-called heavy water. The chemical formula of water is H2O. Two hydrogen atoms and one oxygen atom. In heavy water, the normal hydrogen atoms are replaced with isotopes that are slightly heavier: deuterium. Hence the name heavy water. If you measure out a quantity of heavy water and drink it and wait a few hours, these heavier water molecules will have mixed nicely with all your normal water molecules. If you then take some fluid and measure it, you can precisely calculate what part of that fluid consists of heavy water. And consequently, you know exactly how much water it had to spread over: your total body fluid. You can apply this same principle with an isotope that hardly enters the cells, for example, sodium bromide, allowing you to precisely determine how much extracellular fluid is present. If you then subtract the extracellular fluid from the total body fluid, you also know how much is intracellularly present, namely: the rest.

Results of the study by Powers et al.

This principle was applied by Powers et al. [4]. The results were not directly what you would expect based on the two previous studies. The subjects were supplemented with creatine, and measurements were taken after both 7 and 28 days. What they found was that total body fluid increased. No surprise so far. What was a bit more surprising, however, was that the ratio between intracellular and extracellular fluid remained the same. In other words, the fluid ended up both in the extracellular and intracellular compartments.

Contradictions in the literature

Collectively, the literature does not give a clear answer to the question of where the fluid goes. The gold standard (isotope dilution analysis) tells us that it ends up both outside and inside the cells. However, the other two methods discussed, MFBIA and magnetic resonance, indicate that it only ends up in the cells. It could be that the fluid first ends up in the cells and later also outside the cells. The study using isotope dilution analysis took measurements after 7 and 28 days, while the other two studies did this after 3 and 5 days. It could also simply be that MFBIA gave an unreliable result, due to quite a few uncertainties associated with it. But for me, it remains difficult to say why the magnetic resonance method did not align with isotope dilution analysis. Perhaps it was due to the muscle that was examined, namely a bending muscle of one of the fingers. Anatomically, it’s quite different from the major skeletal muscles. My gut feeling thinks it ends up in the muscle cells…

Do some creatine variants cause more fluid retention than others?

There’s actually no reason to believe that certain creatine variants cause more fluid retention than others. The creatine that ends up in your muscles is always exactly the same, regardless of the form you put in your mouth. Yet, it’s often said that the creatine variant Kre-Alkalyn does not cause fluid retention. This is also one of their marketing points. However, Kre-Alkalyn is no different from creatine monohydrate in a capsule, along with anti-caking agent, sweetener, and sodium carbonate. The only reason I can think of for this claim is that not enough Kre-Alkalyn is taken to increase the creatine concentration in the muscles. The recommended dosage of Kre-Alkalyn is rather on the low side for this purpose. For instance, a study with Kre-Alkalyn supplementation also shows that it does not increase creatinine concentration as much as creatine monohydrate when the recommended dosage of 1.5 grams per day is followed [5]. Something similar can be said for creatine ethyl ester. This creatine variant rapidly degrades into the useless creatinine [6], making it less effective in increasing creatine concentration in the muscles [7]. In short: creatine variants do not cause less fluid retention than good old creatine monohydrate. Unless they fail to saturate the muscles with creatine as effectively, but then they also provide less results…

References

1. Mihic, Sasa, et al. “Acute creatine loading increases fat-free mass, but does not affect blood pressure, plasma creatinine, or CK activity in men and women.” Medicine and Science in Sports and Exercise2 (2000): 291-296.
2. Ziegenfuss, Tim N., Lonnie M. Lowery, and PETER WR Lemon. “Acute fluid volume changes in men during three days of creatine supplementation.” J Exerc Physiol 1.3 (1998): 1-9.
3. Saab, George, et al. “Changes in human muscle transverse relaxation following short-term creatine supplementation.” Experimental physiology3 (2002): 383-389.
4. Powers, Michael E., et al. “Creatine supplementation increases total body water without altering fluid distribution.” Journal of athletic training1 (2003): 44.
5. Jagim, Andrew R., et al. “A buffered form of creatine does not promote greater changes in muscle creatine content, body composition, or training adaptations than creatine monohydrate.” Journal of the International Society of Sports Nutrition1 (2012): 43.
6. Gufford, Brandon T., et al. “pH-dependent stability of creatine ethyl ester: relevance to oral absorption.” Journal of dietary supplements3 (2013): 241-251.
7. Spillane, Mike, et al. “The effects of creatine ethyl ester supplementation combined with heavy resistance training on body composition, muscle performance, and serum and muscle creatine levels.” Journal of the International Society of Sports Nutrition 1 (2009): 6.