A typical creatine supplementation protocol consists of a loading phase of 20 g CM/d or 0.3 g CM/kg/d split into 4 daily intakes of 5 g each, followed by a maintenance phase of 3-5 g CM/d or 0.03 g CM/kg/d for the duration of the supplementation period . Other supplementation protocols are also used such as a daily single dose of around 3 – 6 g or between 0.03 to 0.1 g/kg/d [15,55] however this method takes longer (between 21 to 28 days) to produce ergogenic effects . Sale et al  found that a moderate protocol consisting of 20 g CM taken in 1g doses (evenly ingested at 30-min intervals) for 5 days resulted in reduced urinary creatine and methylamine excretion, leading to an estimated increase in whole body retention of creatine (+13%) when compared with a typical loading supplementation protocol of 4 x 5 g/d during 5 days (evenly ingested at 3 hour intervals). This enhancement in creatine retention would lead to a significantly higher weight gain when people follow a moderate protocol ingestion of several doses of small amounts of CM evenly spread along the day.
Cornelissen, V. A., Defoor, J. G., Stevens, A., Schepers, D., Hespel, P., Decramer, M., Mortelmans, L., Dobbels, F., Vanhaecke, J., Fagard, R. H., and Vanhees, L. Effect of creatine supplementation as a potential adjuvant therapy to exercise training in cardiac patients: a randomized controlled trial. Clin.Rehabil. 2010;24(11):988-999. View abstract.
Recommended Dose: 3-6 grams before or during exercise. A ratio of two parts leucine to one part each of isoleucine and valine appears to be most beneficial. As Krissy Kendall, PhD, explains in "The Top 7 Supplements to Boost Endurance Performance," BCAAs can be just as effective for endurance athletes like runners, rowers, and cyclists as they can be for lifters and bodybuilders.
Listen, I know in the beginning of this post I was sympathetic to your problem, but I am also here to say, Suck It Up. I can tell you that to gain weight, you need to focus on making your meals a habit rather than an afterthought. Your body is pre-programmed with your genetic disposition. And in your case, you have a very fast metabolism that digests and burns calories quickly. Focus on having 5-6 calorie-dense meals a day spaced 2-3 hours apart so that your body is constantly being provided with something to metabolize and build muscle.
Beast Creature could be another good option for female athletes. It’s tasty, it contains five types of creatine, and it contains ingredients that could improve fat loss by increasing insulin sensitivity. One potential bonus is that it also has 70 percent of your daily biotin, a nutrient often included in women’s multivitamins due its purported benefits for hair and nails.
Energy: Energy is found in amino acids, also known as creatine, produced naturally in the body and also found in meat such as beef, chicken and pork. The problem with naturally found creatine is that the amount of protein in it is not high, which therefore, draws bodybuilders to supplement it with a powdered version. Bodybuilders use creatine to increase anaerobic energy; this allows them to lift weights for longer periods of time. Creatine also helps to give volume to the muscle cells by adding more water in them, thus making them look fuller.
Another study demonstrated that females receiving 4 days of high-dose creatine intake (20 g/day) followed by low-dose creatine intake (5 g/day) during 10 weeks of resistance training (3hours/week) increased muscle PCr concentrations by 6%. Also, maximal strength of the muscle groups trained increased by 20-25%, maximal intermittent exercise capacity of the arm flexors increased by 10-25% and fat-free mass increased by 60% .
A quantitative, comprehensive scientific summary and view of knowledge up to 2007 on the effects of creatine supplementation in athletes and active people was published in a 100 citation review position paper by the International Society of Sports Nutrition. More recent literature has provided greater insight into the anabolic/performance enhancing mechanisms of creatine supplementation [15,25] suggesting that these effects may be due to satellite cell proliferation, myogenic transcription factors and insulin-like growth factor-1 signalling . Saremi et al  reported a change in myogenic transcription factors when creatine supplementation and resistance training are combined in young healthy males. It was found that serum levels of myostatin, a muscle growth inhibitor, were decreased in the creatine group.
Synthesis primarily takes place in the kidney and liver, with creatine then being transported to the muscles via the blood. The majority of the human body's total creatine and phosphocreatine stores is located in skeletal muscle, while the remainder is distributed in the blood, brain, and other tissues. Typically, creatine is produced endogenously at an estimated rate of about 8.3 mmol or 1 gram per day in young adults. Creatine is also obtained through the diet at a rate of about 1 gram per day from an omnivorous diet. Some small studies suggest that total muscle creatine is significantly lower in vegetarians than non-vegetarians, as expected since foods of animal origin are the primary source of creatine. However, subjects happened to show the same levels after using supplements.