Mercimek-Mahmutoglu, S., Stoeckler-Ipsiroglu, S., Adami, A., Appleton, R., Araujo, H. C., Duran, M., Ensenauer, R., Fernandez-Alvarez, E., Garcia, P., Grolik, C., Item, C. B., Leuzzi, V., Marquardt, I., Muhl, A., Saelke-Kellermann, R. A., Salomons, G. S., Schulze, A., Surtees, R., van der Knaap, M. S., Vasconcelos, R., Verhoeven, N. M., Vilarinho, L., Wilichowski, E., and Jakobs, C. GAMT deficiency: features, treatment, and outcome in an inborn error of creatine synthesis. Neurology 8-8-2006;67(3):480-484. View abstract.

Despite a possible decreasing creatine content in the muscles when maintenance is deemed suboptimal, the overall retention of weight and lean mass is merely additive over time. This is thought to be due to increases in skeletal muscle production (increase in body weight) compensating for the progressive declines in water and glycogen content (decreases in body weight).

While this nonessential amino acid may not deliver earth-shattering PRs or extreme muscle growth, it does play an important role in repair and recovery. Glutamine works by removing excess ammonia, which can accumulate during intense exercise, helping to regulate your body's acid-base balance. Individuals who are engaged in heavy resistance training, two-a-day training splits, or are in a calorie deficit may benefit from the extra support of glutamine supplementation.

Hopefully I didn’t put a big damper on your Captain-America fueled dreams! I just want to set proper expectations so you don’t get discouraged with slow progress, and instead get SUPER encouraged with any progress. Getting strong should be freakin’ fun! Weirdly enough, once I stopped trying to get there quickly is when I started to actually make permanent progress.
As you've probably heard from any muscle-bound behemoth you've ever encountered, protein is the key to building muscle. Just because the shake-pounding meathead has become a trope, however, doesn't mean they're wrong; protein really is the fuel your muscles need to grow. That's real capital-S Science, not just bro-science manufactured by supplements companies.
Syndromes caused by problems metabolizing creatine. Some people have a disorder that prevents their body from making creatine. This can lead to low levels of creatine in the brain. Low levels of creatine in the brain can lead to decreased mental function, seizures, autism, and movement problems. Taking creating by mouth daily for up to 3 years can increase creatine levels in the brain in children and young adults with a disorder of creatine production called guanidinoacetate methyltransferase (GAMT) deficiency. This can help improve movement and reduce seizures. But it doesn't improve mental ability. Arginine-glycine amidinotransferase (AGAT) deficiency is another disorder that prevents the body from making creatine. In children with this condition, taking creatine for up to 8 years seems to improve attention, language, and mental performance. But taking creatine does not seem to improve brain creatine levels, movement, or mental function in children who have a disorder in which creatine isn't transported properly.
Still, it's important to realize that for everyone, at a certain point, building muscle becomes more difficult. "We all have an endpoint to our genetic potential," Matheny says. "Someone who is starting strength training for the first time can build muscle with a lower percentage of their 1RM [the maximum amount of weight they can lift one time] than a more tenured athlete. The longer you train and the closer you to get to your natural potential, the more specific you need to get with your training and nutrition to keep making progress. And that week-by-week progress will likely be much smaller than it once was."
After all, we want you to be CONFIDENT and not overwhelmed, as the sooner you start strength training, the sooner you learn the ropes and start to make progress! We cover all of this in our free guide, Strength 101: Everything You Need to Know, along with free workout plans – grab all the goodies fo’ free when you join our worldwide Rebellion with your email in the box below!
Free weights include dumbbells, barbells, medicine balls, sandbells, and kettlebells. Unlike weight machines, they do not constrain users to specific, fixed movements, and therefore require more effort from the individual's stabilizer muscles. It is often argued that free weight exercises are superior for precisely this reason. For example, they are recommended for golf players, since golf is a unilateral exercise that can break body balances, requiring exercises to keep the balance in muscles.[27]
We’ll define the “bigger muscle groups” as being chest, back, quads and hamstrings, and the “smaller muscle groups” as being biceps, triceps and maybe abs. Shoulders are really somewhere in the middle, though I tend to lean more toward the “smaller” guidelines. Calves, while technically small, are another muscle group that is somewhere in the middle, and I can really go either way depending on the needs of the person.
^ Jump up to: a b c d e Wilson JM, Fitschen PJ, Campbell B, Wilson GJ, Zanchi N, Taylor L, Wilborn C, Kalman DS, Stout JR, Hoffman JR, Ziegenfuss TN, Lopez HL, Kreider RB, Smith-Ryan AE, Antonio J (February 2013). "International Society of Sports Nutrition Position Stand: beta-hydroxy-beta-methylbutyrate (HMB)". J. Int. Soc. Sports. Nutr. 10 (1): 6. doi:10.1186/1550-2783-10-6. PMC 3568064. PMID 23374455.
In regard to liver fat buildup (steatosis), which is normally associated with reduced availability of S-adenosyl methionine[495][496] and a suppression in expression of genes involved in fatty acid oxidation (PPARα and CPT1), creatine supplementation at 1% of the rat diet alongside a diet that induces fatty liver is able to fully prevent (and nonsignificantly reduce relative to the control given standard diets) the aforementioned changes and the state of steatosis, as well as changes in serum biomarkers (glucose and insulin) that accompany steatosis.[125] 
Creatine is normally metabolized into creatinine (note the difference in spelling), which is eliminated by the kidneys under normal conditions. When the kidneys fail and cannot clear the blood as effectively, many metabolites get “backlogged” in the blood. Creatinine is easy to measure and as such it is a biomarker of kidney damage.[623][624] If serum creatinine levels are elevated, the doctor may suspect some kidney damage. Low-dose creatine (≤5 g/day) may not cause alterations in this biomarker in otherwise normal adults[524][625][525] but high doses of supplemental creatine may cause a false positive (an increase in creatinine, due to creatine turning into creatinine, which does not signify kidney damage) and is a diagnostic error.[520][518][626][523][517] Most studies, however, have noted only a small increase in creatinine levels even with doses ≈20 g/day.[524][626][627]

On top of this, you’ll need to consume more calories than you’re burning. Burning more calories each day than you eat is a great way to lose weight, but if your goal is to put on muscle mass, this can make the process much harder. Your body requires calories to build new muscle tissue, but this can’t occur if all the body’s energy is being used up for daily processes. Because of this, some bodybuilding supplements include weight gainers to help you get more healthy calories in your diet.