Early research in the late 90s showed that creatine supplementation increased total body water. This research utilized creatine supplementation at 20 g/day for six days and was associated with water retention [1].
It does appear that
the most common “adverse” effect of creatine supplementation is the retention of water in the early (first several days) of creatine supplementation [2].
I will explain later why this “adverse” effect is actually a good thing.
As far as water retention due to creatine supplementation, research indicates that three days of creatine supplementation increased total body water and extracellular (i.e., outside the cell) body water [3] and intracellular (i.e., inside the cell) water.
Unfortunately, and what often happens in science, based on these short-term responses, this idea that creatine increases water retention over the long-term has been widely accepted perpetuated throughout the years.
Creatine is an osmotically active substance which means it draws water when its concentration increases.
Therefore, an increase in the body's creatine content could theoretically result in increased water retention.
Creatine is taken up into muscle from circulation by a sodium-dependent creatine transporter. Since the transport involves sodium, water will also be taken up into muscle to help maintain intracellular osmolality.
Osmolality refers to the concentration of dissolved particles of chemicals and minerals -- such as sodium and other electrolytes -- in your blood.
Higher osmolality means you have more particles in your blood. Lower osmolality means the particles are more diluted.
When you consider the activity of the sodium-potassium pumps, it is not likely that intracellular sodium concentration is noticeably affected by creatine supplementation [4].
There are a number of fairly recent exercise training studies lasting anywhere from 5-10 weeks and have also utilized creatine supplementation that demonstrated no increases in total body water.
Resistance-trained males who received creatine at a dose of 0.3 g/kg lean body mass/day for 7 days (approximately 20 g/day) followed by 4 weeks at 0.075 g/kg lean body mass/day for 28 days (approximately 5 g/day) experienced no significant change in intracellular, extracellular, or total body water [5].
In addition, resistance-trained males utilizing a
creatine dosing protocol of 20 g/day for seven days followed by 5 g/day for 21 days had no significant increase in intracellular, extracellular or total body water [6].
Likewise, males and females ingesting creatine (0.03 g/kg/day for six weeks) experienced no significant increase in total body water [7].
Also in agreement, a six week study in non-resistance-trained males utilizing a dosing protocol of 0.3 g/kg lean body mass for five days followed by 0.075 g/kg lean body mass for 42 days produced no significant changes in total body water [8].
In contrast, 28 days of creatine supplementation in healthy males and females showed that creatine supplementation was effective at increasing muscle creatine content which was associated with an increase in body mass and total body water but didn’t alter intracellular or extracellular volumes [9].
A very recent study examining the effects of creatine supplementation and
resistance exercise for 8 weeks and demonstrated a significant increase in total body water and intracellular water when compared to placebo control group.
It’s important to note that the intracellular water is a crucial cellular signal for protein synthesis and thus drives an increase in muscle mass over time [10].
Cell swelling has been identified as an anabolic proliferative signal [11].
Research has demonstrated that there is a decrease in whole body proteolysis and leucine oxidation with these results directionally similar to studies showing cell swelling after infusion of a hypoosmotic solution [12].
In addition, there is a stimulating effect of increased cell volume on glycogen synthesis [13].
The general hypothesis from experts is that creatine-mediated cell swelling activates cell volume-sensitive signaling cascades to adapt to the intracellular and extracellular changes in osmolarity by activating signal transduction pathways for maintaining proper cell function [14].
Although there is mixed evidence showing both increases in water retention and no alterations in total body water. It’s important to note that even if there is water retention, it is primarily intracellular.
Research indicates that this intracellular swelling effectively acts as an anabolic signal and can stimulate protein synthesis and inhibit protein degradation, which in effect can
cause muscle cell growth.
References:
1. Hultman, E., et al., Muscle creatine loading in men. J Appl Physiol (1985), 1996. 81(1): p. 232-7.
2. Hall, M. and T.H. Trojian, Creatine supplementation. Curr Sports Med Rep, 2013. 12(4): p. 240-4.
3. Rosene, J.M., et al., The effects of creatine supplementation on thermoregulation and isokinetic muscular performance following acute (3-day) supplementation. J Sports Med Phys Fitness, 2015. 55(12): p. 1488-96.
4. Francaux, M. and J.R. Poortmans, Side effects of creatine supplementation in athletes. Int J Sports Physiol Perform, 2006. 1(4): p. 311-23.
5. Andre TL, G.J., McKinley-Barnard SK, Willoughby DS, Effects of five weeks of resistance training and relatively-dosed creatine monohydrate supplementation on body composition and muscle strength and whole-body creatine metabolism in resistance-trained males. Int J Kinesiol Sports Sci., 2016. 4: p. 28–35.
6. Jagim, A.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. J Int Soc Sports Nutr, 2012. 9(1): p. 43.
7. Rawson, E.S., et al., Low-dose creatine supplementation enhances fatigue resistance in the absence of weight gain. Nutrition, 2011. 27(4): p. 451-5.
8. Spillane, M., 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. J Int Soc Sports Nutr, 2009. 6: p. 6.
9. Powers, M.E., et al., Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution. J Athl Train, 2003. 38(1): p. 44-50.
10. Safdar, A., et al., Global and targeted gene expression and protein content in skeletal muscle of young men following short-term creatine monohydrate supplementation. Physiol Genomics, 2008. 32(2): p. 219-28.
11. Pasantes-Morales, H., et al., Mechanisms of cell volume regulation in hypo-osmolality. Am J Med, 2006. 119(7 Suppl 1): p. S4-11.
12. Haussinger, D., et al., Cell swelling inhibits proteolysis in perfused rat liver. Biochem J, 1990. 272(1): p. 239-42.
13. Ritz, P., et al., Effects of changes in water compartments on physiology and metabolism. Eur J Clin Nutr, 2003. 57 Suppl 2: p. S2-5.
14. Parise, G., et al., Effects of acute creatine monohydrate supplementation on leucine kinetics and mixed-muscle protein synthesis. J Appl Physiol (1985), 2001. 91(3): p. 1041-7.
