Bird, L. M., Tan, W. H., Bacino, C. A., Peters, S. U., Skinner, S. A., Anselm, I., Barbieri-Welge, R., Bauer-Carlin, A., Gentile, J. K., Glaze, D. G., Horowitz, L. T., Mohan, K. N., Nespeca, M. P., Sahoo, T., Sarco, D., Waisbren, S. E., and Beaudet, A. L. A therapeutic trial of pro-methylation dietary supplements in Angelman syndrome. Am J Med Genet.A 2011;155A:2956-2963. View abstract.

It is known that intracellular energy depletion (assessed by a depletion of ATP) stimulates AMPK activity in order to normalize the AMP:ATP ratio,[333][334] and when activated AMPK (active in states of low cellular energy[335] and colocalizes with creatine kinase in muscle tissue[336]) appears to inhibit creatine kinase via phosphorylation (preserving phosphocreatine stores but attenuating the rate that creatine buffers ATP). While phosphocreatine technically inhibits AMPK, this does not occur in the presence of creatine at a 2:1 ratio.[334] It seems that if the ratio of phosphocreatine:creatine increases (indicative of excess cellular energy status) that AMPK activity is then attenuated, since when a cell is in a high energy status, there is less AMP to directly activate AMPK.[334][336][337]
“Compared to training for strength, intensity is going to drop during the hypertrophy phase of a program, with intensity sitting between 50 and 75 percent of the person’s 1RM, the maximum weight he or she can lift for one rep,” says Ava Fitzgerald, C.S.C.S., C.P.T., a sports performance coach with the Professional Athletic Performance Center in New York.

Key point: Past a certain number of sets, the marginal increases in protein synthesis NO LONGER outweigh the cost of doing more sets. If 8 sets of chest exercises produce 95% of possible muscle protein synthesis… then it makes very little sense to do ANOTHER 10 sets (like most chest workouts) to try and inch out the final 5% of stimulation. Those extra 10 sets are simply damaging your muscle unnecessarily and impairing your ability to recover.
Creatine ethyl ester increases muscle levels of creatine to a lesser degree than creatine monohydrate.[72] It may also result in higher serum creatinine levels[73] due to creatine ethyl ester being converted into creatinine via non-enzymatic means in an environment similar to the digestive tract.[74][75] At equal doses to creatine monohydrate, ethyl ester has failed to increase water weight after 28 days of administration (indicative of muscle deposition rates of creatine, which are seemingly absent with ethyl ester).[76] 

“Imagine you've fasted for over eight hours,” he says. “At breakfast, you're firing your metabolism off really high. If you don't eat for another five hours, your metabolism starts to slow right down and you have to try and kickstart it again with your next meal. If you eat every two and a half to three hours, it's like chucking a log on a burning fire.”
In a study on Alpha-Lipoic Acid, 1,000mg of ALA paired with 100g sucrose and 20g creatine monohydrate was more effective in increasing muscular creatine levels relative to creatine alone and creatine combined with sucrose.[600] This apparent augmentation of creatine uptake into muscle cells was used alongside a loading period. Another study investigating a nutrient mixture (150g glucose, 20g creatine, 2g/kg bodyweight glycerol) on heat tolerance in trained athletes found that replacing one third (50g) of the glucose with 1g ALA resulted in no significant differences between groups (in regard to heat tolerance and cardiovascular performance) despite the reduction of 50g carbohydrate.[601]
Naturo Nitro Creatine Chrome could be an interesting choice for women. It’s actually magnesium creatine chelate, a type of creatine that may help to improve performance without increasing water weight. We don’t have a lot of studies on it just yet, but the research we do have suggests it could potentially be a good choice for women who want to improve performance without experiencing the “bloat” of regular creatine.
A study using creatine at 0.02% of a face cream (confounded with 8% glycerol and 0.4% Guarana) was able to exert a skin-tightening effect over 6 weeks, reducing wrinkles and jowl volume.[541] Combination therapy has also been used with creatine and folic acid (both in vitro[543] and in vivo), resulting in increased skin firmness and reduced coarse and fine wrinkles.[544]
Athletic performance. Creatine seems to help improve rowing performance, jumping height, and soccer performance in athletes. But the effect of creatine on sprinting, cycling, or swimming performance varies. The mixed results may relate to the small sizes of the studies, the differences in creatine doses, and differences in test used to measure performance. Creatine does not seem to improve serving ability in tennis players.

Safety. Iron overload may cause a disease called hemochromatosis in some susceptible people. Iron supplements should only be prescribed by a doctor, and for athletes or those who train heavily, a sports physician combined with a sports dietitian may be preferable. Be sure to take care with this because iron supplements should not be taken casually. Iron supplements may cause constipation and gastric upset in some people.

Creatine supplementation (11.4g) with glycerol (1g/kg; per se effective[394][395]) and glucose (75g) in endurance runners in the heat appears to attenuate the increase in internal temperature associated with an increase in total body water of 0.71+/-0.42L, while performance (VO2 max and running economy) were unaffected over 30 minutes.[3] Creatine is effective without glycerol (20g daily with 140g of glucose polymer over a week),[346] again without an improvement in physical performance.
Extracellular creatine (creatine outside of a cell) appears to influence creatine uptake into a cell. It seems that prolonged and excessive levels of creatine actually suppress uptake (a form of negative regulation to prevent excessive influx).[180] In vitro studies in rat muscle cells have shown that including 1mM creatine into cell culture medium substantially reduces creatine uptake into cells. The inhibitory effect was partially negated by protein synthesis inhibitors, suggesting that high levels of creatine induce the expression of a protein that suppresses creatine transporter activity.[180] Similar findings were reported in a later study in cultured mouse myoblasts, which noted a 2.4-fold increase in intracellular creatine levels in the presence of the protein synthesis inhibitor cyclohexamide.[174]
As I mentioned earlier, the exercises that come first in your workout (aka primary compound exercises) should usually be done in the 5-8 rep range. Exercises in the middle (aka your secondary compound exercises) should usually be done in the 8-10 rep range. Exercises done at the end of your workout (which is typically where isolation exercises belong) should usually be done in the 10-15 rep range.

In regard to the blood brain barrier (BBB), which is a tightly woven mesh of non-fenestrated microcapillary endothelial cells (MCECs) that prevents passive diffusion of many water-soluble or large compounds into the brain, creatine can be taken into the brain via the SLC6A8 transporter.[192] In contrast, the creatine precursor (guanidinoacetate, or GAA) only appears to enter this transporter during creatine deficiency.[192] More creatine is taken up than effluxed, and more GAA is effluxed rather than taken up, suggesting that creatine utilization in the brain from blood-borne sources[192] is the major source of neural creatine.[193][192] However, “capable of passage” differs from “unregulated passage” and creatine appears to have tightly regulated entry into the brain in vivo[193]. After injecting rats with a large dose of creatine, creatine levels increased and plateaued at 70uM above baseline levels. These baseline levels are about 10mM, so this equates to an 0.7% increase when superloaded.[193] These kinetics may be a reason for the relative lack of neural effects of creatine supplementation in creatine sufficient populations.
A good way to determine how much fat in grams you should be taking in is to multiply your calorie intake by 0.001 for maximum trans-fats; by 0.008 for maximum saturated fats; and by 0.03 for the "good fats". For example, for a 2,500-calorie diet, you would limit trans-fats to 3g or less, saturated fats to 20g or less, and up to 75g of mono- and polyunsaturated fats.
The biggest mistake among young would-be bodybuilders is overdoing it, followed by not learning the proper techniques. Take those breaks and follow the correct form, or you'll give your body stress and injuries instead of muscle. Also make sure you're getting a large but balanced diet. Teens going through growth spurts need lots of food, especially when they're working out.

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!

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.
The maximum amount of creatine the body can store is about 0.3 gram per kilogram of body weight [6]. The creatine content of skeletal (voluntary) muscles averages 125 millimoles per kilogram of dry matter (mmol/kg/dm) and ranges from about 60 to 160 mmol/kg/dm. Approximately 60% of muscle creatine is in the form of PCr. Human muscle seems to have an upper limit of creatine storage of 150 to 160 mmol/kg/dm. Athletes with high creatine stores don't appear to benefit from supplementation, whereas individuals with the lowest levels, such as vegetarians, have the most pronounced increases following supplementation. Without supplementation, the body can replenish muscle creatine at the rate of about 2 g/day [7].

Those 5-pound dumbbells were a great place to start as a beginner, but if you've been lifting weights for a while, it's time to bump up the weight. “You can use both exercise machines and free weights,” explains Michele Olson, PhD, exercise physiologist, professor of exercise science at Auburn University Montgomery, “but, if you are not lifting heavy enough weight, it doesn’t matter if you are primarily using free weights or machines.” In order to build muscle, you must break down muscle tissue using a weight that is challenging enough to cause micro-tears, which when repaired, form denser, stronger fibers.
If you're serious about putting on some muscle, then the most efficient way to do it is with three intense resistance training sessions and two lighter intensity workouts per week. “You need to have consistency in a workout program, hitting at least each muscle group two times a week to build muscle,” explains Lovitt. If you’re looking to switch up exercises, Olson suggests swaps such as sumo squats instead of traditional squats; step-ups on a bench instead of lunges; and then rotating back to the former. “These types of variation can be very effective in developing muscles, but the weights must still be fairly heavy that you’re using,” she says.
For the bench press, start with a weight that you can lift comfortably. If you are a beginner, try lifting the bar along with 5lbs or 10lbs on each side. With arms at shoulder-width apart, grab onto the bar and slowly lower the bar until it's at nipple level; push up until your arms are fully extended upwards. Do 8–10 repetitions (reps) like this for three sets (3 x 8), adding additional weight each set. Once you have a few months of practice, slowly increase weight and go down to 6–8 reps per set, aiming to reach muscle failure at the end of the third set.