I'm 6'1" 175 pounds 27 years old. I would like to increase my general muscle mass and reduce my stomach fat. I would consider myself and ectomorph (hard gainer) as I have never really developed much muscle while I've always been very active in sports and periodic weight training. Over the past year I lost about 30 pounds (nearly all fat) by reducing my caloric intake effectively and regular whole body exercises. I was on my way to my ideal body composition until I became a bike courier. I've been a bike messenger for 9 months and recently my stomach fat has started to return. I'm riding 50+ miles each weekday riding for 9 hours a day. How many calories should I be eating? I've tried everywhere between 2400-3,500 cal/day. Is it possible for me to be eating too few calories while still accumulating stomach fat? Is it realistic for me to be able to maintain or even build muscle mass in this scenario? Please help, thanks.
Creatine, the amino acid, naturally helps your body produce more adenosine triphosphate, or ATP, a small molecule that’s actually your body's primary energy source. But research shows that your body is only capable of storing enough ATP for 8 to 10 seconds of high-intensity exercise — and after that, it needs to produce new ATP for you to continue. (9)
In the stomach, creatine can degrade by about 13% due to the digestive hormone pepsin, as assessed by simulated digestion.[127] Although creatinine is a known byproduct of creatine degradation, simulated gastric digestion did not increase creatinine levels, indicating that other breakdown products were formed. However, creatinine was noted to increase in the presence of pancreatin, a mixture of pancreatic enzymes.[127] 
People sometimes walk up and touch him, as if unsure if he is a man or a machine. What they do not realize is that beneath the stony exterior and self-assuredness is a squishy sense of anxiety and vulnerability. Heath gets nervous every time he strips to his posing trunks. He is rarely satisfied with what he sees in the mirror. He is persistently worried about imperfections others might find, too.
In competitive bodybuilding, bodybuilders aspire to develop and maintain an aesthetically pleasing body and balanced physique.[16][17] In prejudging, competitors do a series of mandatory poses: the front lat spread, rear lat spread, front double biceps, back double biceps, side chest, side triceps, Most Muscular (men only), abdominals and thighs. Each competitor also performs a personal choregraphed routine to display their physique. A posedown is usually held at the end of a posing round, while judges are finishing their scoring. Bodybuilders usually spend a lot of time practising their posing in front of mirrors or under the guidance of their coach.
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]

One of the studies noting a reduction in fatigue in healthy subjects given creatine (8g) for five days prior to a mathematical test noted a relative decrease in oxygenation hemoglobin in the brain and an increase in deoxygenated hemoglobin, which normally indicates a reduction in cerebral oxygenation.[245] The authors made note of how cytoplasmic phosphocreatine can increase oxygen uptake into cells (noted in vitro in a concentration dependent manner between 0-25mM[245]) and suggested that either cells were taking up more oxygen from hemoglobin, or that increased mitochondrial efficiency resulted in less of a need for oxygen.[245]
During the second trimester, androgen level is associated with sex formation.[13] This period affects the femininization or masculinization of the fetus and can be a better predictor of feminine or masculine behaviours such as sex typed behaviour than an adult's own levels. A mother's testosterone level during pregnancy is correlated with her daughter's sex-typical behavior as an adult, and the correlation is even stronger than with the daughter's own adult testosterone level.[14]

Negative regulators of the creatine transporter (CrT) are those that, when activated, reduce the activity of the CrT and overall creatine uptake into cells. As noted above, CrT activity is positively regulated by mTOR.[158] Consistent with the well-known role of AMPK as a suppressor mTOR signaling,[177] CrT activity has also been shown to be inhibited in response to AMPK activation in kidney epithelial cells.[178] Since AMPK suppresses mTOR via upstream TSC2 activation,[179] the negative regulation of AMPK on CrT activity in these cells appears to occur through an indirect mechanism. Although indirect, activation of AMPK has been noted to reduce the Vmax of the CrT without altering creatine binding, and is involved in internalizing the receptors.[178] This pathway seems to max out at around 30% suppression, with no combination of mTOR antagonists and AMPK inducers further suppressing creatine uptake.[178]

The Organon group in the Netherlands were the first to isolate the hormone, identified in a May 1935 paper "On Crystalline Male Hormone from Testicles (Testosterone)".[185] They named the hormone testosterone, from the stems of testicle and sterol, and the suffix of ketone. The structure was worked out by Schering's Adolf Butenandt, at the Chemisches Institut of Technical University in Gdańsk.[186][187]
Testosterone was first used as a clinical drug as early as 1937, but with little understanding of its mechanisms. The hormone is now widely prescribed to men whose bodies naturally produce low levels. But the levels at which testosterone deficiency become medically relevant still aren’t well understood. Normal testosterone production varies widely in men, so it’s difficult to know what levels have medical significance. The hormone’s mechanisms of action are also unclear.
Low testosterone levels may contribute to decreased sex drive, erectile dysfunction, fragile bones, and other health issues. Having low testosterone levels may also indicate an underlying medical condition. See your doctor if you suspect you have low testosterone. A simple blood test is all it takes to check if your testosterone falls within the normal range.

Sandow was so successful at flexing and posing his physique that he later created several businesses around his fame, and was among the first to market products branded with his name. He was credited with inventing and selling the first exercise equipment for the masses: machined dumbbells, spring pulleys, and tension bands. Even his image was sold by the thousands in "cabinet cards" and other prints. Sandow was a perfect "Gracilian", a standard of ideal body proportions close to those of ancient Greek and Roman statues. Men's physiques were then judged by how closely they matched these proportions.

Eat 1.5–3 grams of carbs per pound of your body weight. As with fat, this amount can vary greatly, depending on your personal needs and preferences, so consider these numbers only a starting point. If you’re very skinny and feel that you handle carbs well (i.e. you can eat a lot of them without getting fat), go ahead and eat according to the higher end of the spectrum. The same applies if you’re desperate to gain weight—you should increase your carb intake. If you’re prone to weight gain or feel lethargic on higher carbs, you should eat fewer of them. Again, see our keto guide for more details and options.
For example, say you are pursuing a muscle power objective in which you have decided to perform 3 sets of 8 repetitions each. You'll want to make sure you don't add too much weight so that you are able to perform all 8 repetitions before your muscles are too tired to finish the set. Conversely you'll want to make sure you add enough weight so that you are not simply breezing past the repetitions and finish your sets of plenty of energy still left in the tank. While it may take a few workout sessions to find the right combination, once you'll do it'll be easy to monitor and increase weight as you progress.

Researchers have long been interested in how exercise improves cognitive thinking — and whether it can ward off dementia later in life. Now, a whole slew of new studies is comparing whether strength training affects the brain differently than cardio. One Italian study of 80 older people found that those who completed a 12-week strength regimen showed improved capacity for practical skills, whereas cardio training helped bolster them on analytic tasks. Researchers are still trying to understand the “why” behind this study — but so far, we’re impressed.
^ Kreider RB, Kalman DS, Antonio J, Ziegenfuss TN, Wildman R, Collins R, Candow DG, Kleiner SM, Almada AL, Lopez HL (2017-06-13). "International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine". Journal of the International Society of Sports Nutrition. 14: 18. doi:10.1186/s12970-017-0173-z. PMC 5469049. PMID 28615996.

As the name implies, the muscle power objective can be pursued if you want to achieve maximum size in your muscles or if you want them to be explosively strong (i.e. very powerful for short bursts at a time). In order to develop muscles this way you'll want to use no more than 3 sets in which no more than 8 reps are used. Muscle size and power is often used for muscles that are prominently displayed on the human figure, such as the pectorals, or the biceps and triceps.
Once training is resumed under these conditions, there may be little in the way of caloric support to ensure that protein synthesis and muscle growth occurs. Muscle may even begin to cannibalize itself as the body enters into a catabolic state. Even with the best of diets this can sometimes happen if training demands override the nutritional balance or imbalance.
The sexual hormone can encourage fair behavior. For the study, subjects took part in a behavioral experiment where the distribution of a real amount of money was decided. The rules allowed both fair and unfair offers. The negotiating partner could subsequently accept or decline the offer. The fairer the offer, the less probable a refusal by the negotiating partner. If no agreement was reached, neither party earned anything. Test subjects with an artificially enhanced testosterone level generally made better, fairer offers than those who received placebos, thus reducing the risk of a rejection of their offer to a minimum. Two later studies have empirically confirmed these results.[75][76][77] However men with high testosterone were significantly 27% less generous in an ultimatum game.[78] The Annual NY Academy of Sciences has also found anabolic steroid use which increase testosterone to be higher in teenagers, and this was associated with increased violence.[79] Studies have also found administered testosterone to increase verbal aggression and anger in some participants.[80]
In the hepatic 17-ketosteroid pathway of testosterone metabolism, testosterone is converted in the liver by 5α-reductase and 5β-reductase into 5α-DHT and the inactive 5β-DHT, respectively.[1][155] Then, 5α-DHT and 5β-DHT are converted by 3α-HSD into 3α-androstanediol and 3α-etiocholanediol, respectively.[1][155] Subsequently, 3α-androstanediol and 3α-etiocholanediol are converted by 17β-HSD into androsterone and etiocholanolone, which is followed by their conjugation and excretion.[1][155] 3β-Androstanediol and 3β-etiocholanediol can also be formed in this pathway when 5α-DHT and 5β-DHT are acted upon by 3β-HSD instead of 3α-HSD, respectively, and they can then be transformed into epiandrosterone and epietiocholanolone, respectively.[157][158] A small portion of approximately 3% of testosterone is reversibly converted in the liver into androstenedione by 17β-HSD.[156]
A child’s ability to regenerate high energy phosphates during high intensity exercise is less than that of an adult. Due to this, creatine supplementation may benefit the rate and use of creatine phosphate and ATP rephosporylation. However, performance in short duration high-intensity exercise can be improved through training therefore supplementation may not be necessary [54].

Researchers described the study as one of the first to examine how strength training can reduce the risk of cardiovascular disease, separate from the effects of aerobic activity like running or long walks. The point: for those who are not meeting recommended guidelines for aerobic activity—perhaps because they lack the time—bursts of weight training can be enough.
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.
Generally, you should consume about 20 grams of protein with some carbs shortly after a workout. During the post-workout anabolic window, you’ll also want to limit fats, which can slow the absorption of protein. While there is some recent research that suggests the window may actually extend up to several hours following exercise, there’s no harm in getting nutrients in early as long as you’re sticking to your overall caloric and macronutrient goals.
It can be hard to know where to start when beginning strength training. There are countless exercises you can do, some of which work some muscles, but not others. There are safety concerns to beware of, a wide variety of sometimes confusing equipment to help you in your efforts, and so on. With some familiarity of the basics of getting started with strength training, actually doing so can become far less daunting, and you can begin to craft a routine that is targeted toward helping you achieve your personal goals.
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.

Anti-cancer effects have been observed with the creatine analogue cyclocreatine[456][104][457] and have been replicated with creatine itself. These effects tend to be a reduction in which the rate of implanted tumors progresses.[458][459] It is suspected that these observed effects (inhibition of growth or attenuation of the rate of growth) are not due to the bioenergetic effect of creatine, secondary to creatine kinase. These anti-cancer effects do not have a known reliability, as the expression of creatine kinase varies widely based on the type of tumor.[460] However, some studies suggest an inverse relationship between tumor progression in mice and concentrations of creatine in cells, with creatine depletion coinciding with tumor development.[460]
Eating the right carbs is important too. Carbohydrate is stored in your body in the form of glycogen. Glycogen in the muscles is an important fuel reserve during intense physical exercise or in times of energy restriction – protein sparing. It is best to restrict or to keep away from junk carbohydrates such as sweets, cakes, and biscuits, and stick to foods like porridge, pasta (wholemeal), rice (brown), bread (wholegrain), and cereals (try to choose the versions with low or reduced sugar and salt). For more on carbohydrate and the effect of sugar on the body, click here.