Kerksick, C. M., Wilborn, C. D., Campbell, W. I., Harvey, T. M., Marcello, B. M., Roberts, M. D., Parker, A. G., Byars, A. G., Greenwood, L. D., Almada, A. L., Kreider, R. B., and Greenwood, M. The effects of creatine monohydrate supplementation with and without D-pinitol on resistance training adaptations. J.Strength.Cond.Res. 2009;23(9):2673-2682. View abstract.

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.
Peirano, R. I., Achterberg, V., Dusing, H. J., Akhiani, M., Koop, U., Jaspers, S., Kruger, A., Schwengler, H., Hamann, T., Wenck, H., Stab, F., Gallinat, S., and Blatt, T. Dermal penetration of creatine from a face-care formulation containing creatine, guarana and glycerol is linked to effective antiwrinkle and antisagging efficacy in male subjects. J.Cosmet.Dermatol. 2011;10(4):273-281. View abstract.
McArdle’s disease is a myopathy associated with impaired glucose release from glycogen and impairments in muscle function at times when glucose would be the primary energy substrate. Creatine is thought to be therapeutic, but has shown differing effects in the two trials so far (both benefit and worsening of symptoms) for currently unknown reasons.
Young adult athletes who reported creatine usage for over two years prior to the study (retrospective design) were not significantly different than controls.[501] Elsewhere, in a similar cohort of athletes reporting creatine usage for up to four years, failed to note significant differences in liver enzymes, although a nonsignificant reduction in LDH was noted.[502]
Competitive and professional bodybuilders, however, can often build up to two to three pounds of muscle per month during dedicated bulking periods. "But they are living and breathing muscle growth. They aren't just in and out of the gym like most people," Simpson says, noting that under extreme conditions, hyperplasia, or the growth in the number of muscle cells in a given muscle tissue, may actually occur, further adding to muscle growth results.
Gain mass: One of the most popular reasons for people to take body building supplements is to gain weight and that is why protein powder is much sought after. Protein is the building block of muscles and therefore, bodybuilders use protein powder to help repair muscles, speed recoveries and preserve muscle mass. They usually consume 1 to 2 grams of protein per pound of body weight every day. 
Despite creatine not interfering with UV(A) irradiation acting upon a cell or the production of oxidation due to it, creatine appears to prevent the functional consequences (such as mitochondrial DNA damage) due to preventing an ATP depletion in the cell, which would normally precede a reduction in mitochondrial membrane potential and mutagenesis, but this effect is prevented for as long as creatine stores are sufficient.[446] Creatine has also been noted to near-fully protect mitochondrial DNA from hydroxyl radicals and oxidative damage, although there was no protective effect for nuclear DNA, due to it being less sensitive to hydroxyl radicals.[447]
Creatine is most commonly used for improving exercise performance and increasing muscle mass in athletes and older adults. There is some science supporting the use of creatine in improving the athletic performance of young, healthy people during brief high-intensity activity such as sprinting. Because of this, creatine is often used as a dietary supplement to improve muscle strength and athletic performance. In the U.S., a majority of sports nutrition supplements, which total $2.7 billion in annual sales, contain creatine.
If you're 12 weeks out from a competition, you want to maintain as much muscle as possible while torching fat from every angle. This means low-intensity cardio – high intensity cardio speeds up your metabolism and burns fat very quickly, so you run the risk of burning muscle too, Terry says – either first thing in the morning on an empty stomach, or immediately after your weights session, once you’ve depleted those glycogen levels.
Most people require around 20 calories per pound (or 44 kcal / kg) of bodyweight to gain muscle mass. Using a 180-pound (82kg) male as an example, the required daily calorie intake is 3600 calories (20 kcal x 180 lb = 3600 kcal). When it comes to gaining weight, it is likely that you may put on a few pounds of fat along the way, but if you do find your body fat increasing, either increase the amount of aerobic exercise (moderate intensity) you are doing or slightly reduce the total number of calories you are consuming. Remember you can’t force feed muscle gain!

When looking specifically at human studies, there has been a failure of creatine supplementation to induce or exacerbate kidney damage in people with amyotrophic lateral sclerosis (ALS). Subjects do not experience kidney damage for up to or over a year’s worth of supplementation in the 5-10g range.[505][506][507] Postmenopausal women,[517] people with type II diabetes,[518] people on hemodialysis,[313] otherwise healthy elderly,[519] young people,[454][520][521] and athletes do not experience kidney damage either.[324] Moreover, numerous scientific reviews on both the long- and short-term safety of supplemental creatine have consistently found no adverse effects on kidney function in a wide range of doses.[522][523][524][452][525][451][526][527] However, while doses >10 g/day have been found not to impair kidney function, there are fewer long-term trials using such high chronic daily intakes.[527]
Heath is an unlikely Mr. Olympia. He grew up on playgrounds in Seattle playing basketball. His backcourt mate on the 1998 state championship team at Rainier Beach High School was Jamal Crawford, still in the N.B.A. Heath, just 5 feet 9 inches and a naturally chiseled 175 pounds, got a Division I basketball scholarship at the University of Denver. He majored in business and averaged 1.3 points over four seasons.
For a 180 lb (82 kg) person, this translates to 25 g/day during the loading phase and 2.5 g/day afterward, although many users take 5 g/day due to the low price of creatine and the possibility of experiencing increased benefits. Higher doses (up to 10 g/day) may be beneficial for people with a high amount of muscle mass and high activity levels or for those who are non-responders to the lower 5 g/day dose.
One case study exists of a man with focal segmental glomerulosclerosis who experienced an accelerated rate of GFR decline during supplementation (5g thrice daily for loading, then a 2g maintenance for seven weeks) which was partially reversed upon supplement cessation. This was deemed strong circumstantial evidence, and the brand of supplement was not named.[616] Elsewhere, interstitial nephritis associated with creatine supplementation has been reported in a man, although symptoms arose four weeks after supplementation started with no evidence to support correlation.[617] Some studies involving athletes and various dietary supplements have attempted to draw a correlation with creatine and cases of rhabdomyolysis.[618][619][620][621] Finally, one study in a diabetic person ingesting both metformin and creatine resulting in metabolic acidosis has attempted to place causation on creatine, but it did not establish causation or circumstantial evidence.[622]