Creatine synthesis primarily occurs in the liver and kidneys.[2][16] On average, it is produced endogenously at an estimated rate of about 8.3 mmol or 1 gram per day in young adults.[16][17] Creatine is also obtained through the diet at a rate of about 1 gram per day from an omnivorous diet.[16][18] Most of the human body's total creatine and phosphocreatine stores are found in skeletal muscle, while the remainder is distributed in the blood, brain, and other tissues.[17][18]

In fact, in one new study comparing the effects of aerobic exercise versus resistance training on the psychological health of obese adolescents, researchers found that people in the resistance group experienced significantly greater self-esteem and perceived strength over four weeks. But what’s most interesting is that the feeling of getting stronger — rather than any measurable gains — was all it took to give them a boost.

When many people think of someone with a high level of testosterone, they may picture a man loaded with strength, sexual prowess, and machismo. But while high-T has been correlated with all those things, it’s also been correlated with aggression, sexual misconduct, and violence. One of testosterone’s most common uses—as a performance-enhancing steroid—illustrates both sides of the hormone. Injecting steroids can be a quick way for athletes to dramatically improve performance, but the side effects can also be extreme, and can include excessive body hair growth, sexual dysfunction, and the hard-to-corral anger known as “roid rage.”
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.
Creatine has been investigated for its effects on depression, due to the significant changes occurring in brain morphology and neuronal structure associated with depression[246] and low brain bioenergetic turnover in depression[247], perhaps related to abnormal mitochondrial functioning, which reduces available energy for the brain.[248][249] The general association of low or otherwise impaired phosphate energy systems (of which creatine forms the energetic basis of) with depression, has been noted previously.[250][247][251] Due to associations with cellular death and impaired bioenergetics with depression, creatine was subsequently investigated.

So how does that play out in the real world? Well, if, for example, a woman adds 10 pounds of muscle and loses 10 pounds of fat, she’ll burn 40 extra calories per day. Forty calories a day isn’t nearly as significant as a dietary change could be, but for people who are looking to lose weight, it can still make a minor difference over the long term.

There is some research that suggests that creatine can help people with type 2 diabetes by improving insulin sensitivity, glucose uptake into the cells, and glycemic control. This has led many people with T2 to start supplementing their diets with pure creatine to try and reap the benefits. At this time there has been no conclusive research done into the effectiveness of creatine for type 1 diabetics.