guardianactual
MuscleChemistry Registered Member
by Layne Norton
Protein
Protein is probably the single most important macronutrient for the purposes of maintaining muscle on a diet. Dietary protein is hydrolyzed (broken down) into it's constitutive amino acids during digestion. These amino acids are released into the bloodstream where they may then be taken up by cells (usually muscle cells).
Dietary protein is also important; amino acid availability is the single most important variable for protein synthesis to occur. This means that protein synthesis increases in a linear fashion (directly proportional to plasma amino acid concentrations) until the plasma amino concentrations are approximately twice that of normal plasma concentrations 1.
To generalize for the less scientifically inclined, ingesting enough dietary protein is important for someone who is looking to gain muscle, or maintain it while dieting. Dietary protein spares muscle by helping increase protein synthesis (and thus induce net muscle gain) and by acting as a muscle sparing substrate as it can be used for glucogensis (synthesis of glucose).
Dietary protein however, is not as muscle sparing as are carbohydrates when used as a substrate for glucose synthesis. Protein is also an "expensive" molecule for your body to use as energy. The body would much rather store amino acids than oxidize them as protein oxidation yields less net ATP produced per amino acid when compared to fat or carbohydrates2. Therefore, it can be stated that dietary protein has a thermogenic effect on the body.
Carbohydrates
Carbohydrates have probably gotten the worst reputation of the macronutrients due to the ketogenic dieting rave. Ketogenic dieting refers to reducing carbohydrate intake to practically nothing, while simultaneously raising fat and protein intake. With little glucose for the brain to utilize for energy, the body will begin producing ketones.
Ketones are by-products of fat oxidation and the brain can use ketones for energy. This does indeed have a potent fat burning effect, as insulin levels will be severely reduced due to lack of carbohydrate intake. Low insulin levels correlate with high rates of fat oxidation.
Indeed, the ketogenic diet may be the single best way to lose the maximum amount of body fat in the shortest amount of time. However, if you will quickly refer to our goals during a pre-contest diet you will notice that maintaining muscle is number one on our list, with fat loss second.
If one has not properly scheduled enough time to lose body fat and they are in need of drastic measures, then using a ketogenic diet may be their only choice in order to become contest-ready in time. Unfortunately, they will not maintain an optimum amount of muscle mass.
For those who have given themselves ample time to prepare, I do not suggest using a ketogenic diet. Instead, I recommend reducing carbohydrates, but keeping them high enough to possess the muscle sparing benefits of carbohydrates while still losing body fat.
Learn More About Ketogenic Diets...
There are several main reasons that I recommend retaining carbohydrates. The first reason being that carbohydrates are much more muscle sparing than fats during times of stress when glucose becomes a primary source of fuel (i.e. anaerobic exercise, injury, infection, etc) 3.
There are several main reasons that I recommend retaining carbohydrates. The first reason being that carbohydrates are much more muscle sparing than fats during times of stress when glucose becomes a primary source of fuel (i.e. anaerobic exercise, injury, infection, etc) 3.
The muscle-sparing effects of carbohydrates occur via several different mechanisms. When the body is in a low energy state, it may try to produce energy by converting amino acids to glucose. Carbohydrates prevent this since they can be easily broken down (and converted if need be) to glucose molecules. Carbohydrates then spare dietary protein from oxidation and these proteins can be stored rather than oxidized.
Carbohydrates are also muscle-sparing during exercise. When one lifts heavy weights, the primary pathway that is used to produce ATP (cellular energy currency) is the anaerobic or glycolytic pathway (as the name implies this pathway operates in the absence of oxygen). The only substrate for this pathway is glucose, which can be obtained from dietary carbohydrates or by breaking down glycogen (the cell's stored form of glucose).
If one is on a ketogenic or extreme "low carb" diet however, the body will need to utilize another source to synthesize glucose from. Since glycogen levels are low on a ketogenic diet, the body will actually convert amino acids to glucose and this glucose will be used in the anaerobic pathway to produce ATP. These amino acids will come from dietary protein, amino acids from the cellular amino acid pool, and from muscle tissue. The latter situation is where one would experience muscle loss. Dietary protein would be sacrificed for ATP production and the depleted amino acid pool would not bode well for protein synthesis rates, thus causing a net loss in muscle mass.
Carbohydrates are also muscle sparing because they are a cause of insulin release. Now I know your thinking, "but Layne, you just said in your intro that low insulin levels were great for fat burning!?" Yes, you are correct. I did indeed say that low insulin levels are good for fat burning. Insulin inhibits lipolytic (fat burning) activity and must be kept low if one wishes to burn a maximal amount of fat.
However, the pesky re-occurring theme of maintaining muscle prevents us from totally excluding insulin from our pre-contest diet arsenal, as insulin happens to be one of the most anabolic/anti-catabolic hormones in the body. Insulin binding to the cell membrane causes all sorts of reactions in your body that are beneficial to maintaining and gaining muscle tissue. Insulin inhibits protein breakdown and amino acid oxidation, thus promoting muscle maintenance or gain 1,2.
Insulin also has an antagonist (inhibitory) affect with regards to several catabolic hormones, including cortisol. Cortisol is a hormone that is released during times of stress such as dieting, lifting, injury, etc. Cortisol produces glucose by breaking down proteins, including muscle tissue. Cortisol is the primary catabolic hormone that is released when one lifts or does any kind of activity.
Insulin release inhibits the activity of cortisol by preventing its release from the pancreas, thus sparing muscle tissue from cortisol's catabolic effects. Furthermore, it is interesting to note that long-term exposure of cells to ketones (i.e., ketogenic diet) retard insulin-induced activation of the insulin surface receptor 4. This causes one to become extremely sensitive to carbohydrates when they begin ingesting them again after they finish dieting and could lead to an undesired post diet fat gain.
Carbohydrates act to maintain muscle mass while dieting by maintaining cellular osmotic pressure and cell volume. Cell size is an indicator of the "state" that the body is in. When cells are of large volume, it signals that the body is in a fed state. When cell volume is low it signals that the body is in a starved state. Without delving too far into the science behind this, trust me when I say that you would like your body to think it is in a fed state as this will increase the levels of fat burning hormones and anabolic hormones.
Cell size also indicates the anabolic state of the cell. When cell volume is high, protein synthesis rates increase. If cell volume drops, then protein synthesis levels drop 5,6,7,8. It is easy to infer we would like to maintain cell volume, especially when dieting. The problem with extreme low carbohydrate diets is they cause severe reduction in cell size.
The body stores carbohydrates inside cells as glycogen. For every gram of glycogen stored, the body stores around 2.7 g of water. Therefore, cells that have greater glycogen levels will also have more volume. One can see then how low carbohydrate diets severely decrease cell size due to severe glycogen depletion. Concluding, carbohydrates help maintain muscle by increasing cell volume.
One more issue to consider is performance. If you refer to the goals of a pre-contest diet, you will see that number three maintains that you must keep a high level of intensity in the gym. This is important for several reasons. If performance begins to suffer, then a person will undoubtedly lose strength. This could lead to a subsequent loss of muscle mass due to decreased stimulation from a decreased training overload. Therefore, it is important that performance be kept at an optimal level.
Low glycogen levels have been associated with increased fatigue and decreased performance in athletes (endurance, strength, power output, etc). Several studies have shown that consuming adequate amounts of carbohydrates before, during, and after exercise may attenuate the increased fatigue and increase performance.9-14
It is worth noting that one such study concluded that "the rate of recovery is coupled with the rate of muscle glycogen replenishment and suggests that recovery supplements should be consumed to optimize muscle glycogen synthesis as well as fluid replacement." It can therefore be concluded that an adequate supply of carbohydrates is crucial for maintaining performance and for proper muscle recovery.
Fats
Fats are important molecules and are considered essential to ones survival. Indeed, fats are involved in many of the body's processes which are required for survival. Several key functions of fats in the human body are for energy storage and hormone synthesis. They are the body's preferred source of stored energy and the most efficient molecule for the body to burn. (in terms of energy yield per gram, 9kcals/gram).
The main hormone that fats impact which we are concerned with is testosterone. When calories are restricted, testosterone levels will drop, as the body will suppress its release of anabolic hormones in order to spare nutrients for oxidation (energy production). This makes perfect sense: the body senses it is "starving" and thus it represses it's anabolic hormones to prevent nutrients from being used to increase tissue mass and spares them for energy production.
That's the first hit against testosterone production. Drastically lowering your fat intake is another hit against testosterone production since fatty acids are the substrates for cholesterol synthesis and therefore are also the substrates for testosterone synthesis (cholesterol is converted to testosterone, among other things).
Unfortunately, fats are also easily stored as adipose tissue (body fat) So there must be some type of comprimise between ingesting enough fat for hormone maintenance (and subsequent muscle maintenance) and reducing fat intake enough to decrease body fat.
There has been some research done on the effects of dietary fat on testosterone. The answer to, "how much dietary fat is optimal" is difficult to decipher, as there are major differences in the designs of the performed studies. This makes it difficult to compare them to each other and come up with a "standard" answer.
Several studies concluded that diets low in fat (under 15% of total calories) significantly decreased testosterone levels while diets higher in fat (above 30% of total calories) increased serum testosterone levels.15,16 Rather than continuing with this discussion I will provide a link to an article which covers the subject quite nicely.
To simplify everything that I have said, it seems that one should not lower fat below 15% of daily calories unless they would like to face extreme testosterone deficiencies. Likewise, one should not increase fat to say 40% in order to increase testosterone.
Although fat increases testosterone to a degree, it is important to remember that testosterone is only a small piece of the larger puzzle. There are many other hormones and factors involved in building muscle other than just testosterone. By increasing fat to extremely high levels, there will be less "space" for carbohydrates and protein, both of which are very important for aforementioned reasons.
As with most things in life, moderation is key. In order to keep hormone production regular and fat burning in high gear, while allowing enough "space" to supply adequate carbohydrates and protein for muscle sparing purposes I do not recommend increasing fat above 30% of daily calories.
Part 3 the diet next
Protein
Protein is probably the single most important macronutrient for the purposes of maintaining muscle on a diet. Dietary protein is hydrolyzed (broken down) into it's constitutive amino acids during digestion. These amino acids are released into the bloodstream where they may then be taken up by cells (usually muscle cells).
Dietary protein is also important; amino acid availability is the single most important variable for protein synthesis to occur. This means that protein synthesis increases in a linear fashion (directly proportional to plasma amino acid concentrations) until the plasma amino concentrations are approximately twice that of normal plasma concentrations 1.
To generalize for the less scientifically inclined, ingesting enough dietary protein is important for someone who is looking to gain muscle, or maintain it while dieting. Dietary protein spares muscle by helping increase protein synthesis (and thus induce net muscle gain) and by acting as a muscle sparing substrate as it can be used for glucogensis (synthesis of glucose).
Dietary protein however, is not as muscle sparing as are carbohydrates when used as a substrate for glucose synthesis. Protein is also an "expensive" molecule for your body to use as energy. The body would much rather store amino acids than oxidize them as protein oxidation yields less net ATP produced per amino acid when compared to fat or carbohydrates2. Therefore, it can be stated that dietary protein has a thermogenic effect on the body.
Carbohydrates
Carbohydrates have probably gotten the worst reputation of the macronutrients due to the ketogenic dieting rave. Ketogenic dieting refers to reducing carbohydrate intake to practically nothing, while simultaneously raising fat and protein intake. With little glucose for the brain to utilize for energy, the body will begin producing ketones.
Ketones are by-products of fat oxidation and the brain can use ketones for energy. This does indeed have a potent fat burning effect, as insulin levels will be severely reduced due to lack of carbohydrate intake. Low insulin levels correlate with high rates of fat oxidation.
Indeed, the ketogenic diet may be the single best way to lose the maximum amount of body fat in the shortest amount of time. However, if you will quickly refer to our goals during a pre-contest diet you will notice that maintaining muscle is number one on our list, with fat loss second.
If one has not properly scheduled enough time to lose body fat and they are in need of drastic measures, then using a ketogenic diet may be their only choice in order to become contest-ready in time. Unfortunately, they will not maintain an optimum amount of muscle mass.
For those who have given themselves ample time to prepare, I do not suggest using a ketogenic diet. Instead, I recommend reducing carbohydrates, but keeping them high enough to possess the muscle sparing benefits of carbohydrates while still losing body fat.
Learn More About Ketogenic Diets...
There are several main reasons that I recommend retaining carbohydrates. The first reason being that carbohydrates are much more muscle sparing than fats during times of stress when glucose becomes a primary source of fuel (i.e. anaerobic exercise, injury, infection, etc) 3.
There are several main reasons that I recommend retaining carbohydrates. The first reason being that carbohydrates are much more muscle sparing than fats during times of stress when glucose becomes a primary source of fuel (i.e. anaerobic exercise, injury, infection, etc) 3.
The muscle-sparing effects of carbohydrates occur via several different mechanisms. When the body is in a low energy state, it may try to produce energy by converting amino acids to glucose. Carbohydrates prevent this since they can be easily broken down (and converted if need be) to glucose molecules. Carbohydrates then spare dietary protein from oxidation and these proteins can be stored rather than oxidized.
Carbohydrates are also muscle-sparing during exercise. When one lifts heavy weights, the primary pathway that is used to produce ATP (cellular energy currency) is the anaerobic or glycolytic pathway (as the name implies this pathway operates in the absence of oxygen). The only substrate for this pathway is glucose, which can be obtained from dietary carbohydrates or by breaking down glycogen (the cell's stored form of glucose).
If one is on a ketogenic or extreme "low carb" diet however, the body will need to utilize another source to synthesize glucose from. Since glycogen levels are low on a ketogenic diet, the body will actually convert amino acids to glucose and this glucose will be used in the anaerobic pathway to produce ATP. These amino acids will come from dietary protein, amino acids from the cellular amino acid pool, and from muscle tissue. The latter situation is where one would experience muscle loss. Dietary protein would be sacrificed for ATP production and the depleted amino acid pool would not bode well for protein synthesis rates, thus causing a net loss in muscle mass.
Carbohydrates are also muscle sparing because they are a cause of insulin release. Now I know your thinking, "but Layne, you just said in your intro that low insulin levels were great for fat burning!?" Yes, you are correct. I did indeed say that low insulin levels are good for fat burning. Insulin inhibits lipolytic (fat burning) activity and must be kept low if one wishes to burn a maximal amount of fat.
However, the pesky re-occurring theme of maintaining muscle prevents us from totally excluding insulin from our pre-contest diet arsenal, as insulin happens to be one of the most anabolic/anti-catabolic hormones in the body. Insulin binding to the cell membrane causes all sorts of reactions in your body that are beneficial to maintaining and gaining muscle tissue. Insulin inhibits protein breakdown and amino acid oxidation, thus promoting muscle maintenance or gain 1,2.
Insulin also has an antagonist (inhibitory) affect with regards to several catabolic hormones, including cortisol. Cortisol is a hormone that is released during times of stress such as dieting, lifting, injury, etc. Cortisol produces glucose by breaking down proteins, including muscle tissue. Cortisol is the primary catabolic hormone that is released when one lifts or does any kind of activity.
Insulin release inhibits the activity of cortisol by preventing its release from the pancreas, thus sparing muscle tissue from cortisol's catabolic effects. Furthermore, it is interesting to note that long-term exposure of cells to ketones (i.e., ketogenic diet) retard insulin-induced activation of the insulin surface receptor 4. This causes one to become extremely sensitive to carbohydrates when they begin ingesting them again after they finish dieting and could lead to an undesired post diet fat gain.
Carbohydrates act to maintain muscle mass while dieting by maintaining cellular osmotic pressure and cell volume. Cell size is an indicator of the "state" that the body is in. When cells are of large volume, it signals that the body is in a fed state. When cell volume is low it signals that the body is in a starved state. Without delving too far into the science behind this, trust me when I say that you would like your body to think it is in a fed state as this will increase the levels of fat burning hormones and anabolic hormones.
Cell size also indicates the anabolic state of the cell. When cell volume is high, protein synthesis rates increase. If cell volume drops, then protein synthesis levels drop 5,6,7,8. It is easy to infer we would like to maintain cell volume, especially when dieting. The problem with extreme low carbohydrate diets is they cause severe reduction in cell size.
The body stores carbohydrates inside cells as glycogen. For every gram of glycogen stored, the body stores around 2.7 g of water. Therefore, cells that have greater glycogen levels will also have more volume. One can see then how low carbohydrate diets severely decrease cell size due to severe glycogen depletion. Concluding, carbohydrates help maintain muscle by increasing cell volume.
One more issue to consider is performance. If you refer to the goals of a pre-contest diet, you will see that number three maintains that you must keep a high level of intensity in the gym. This is important for several reasons. If performance begins to suffer, then a person will undoubtedly lose strength. This could lead to a subsequent loss of muscle mass due to decreased stimulation from a decreased training overload. Therefore, it is important that performance be kept at an optimal level.
Low glycogen levels have been associated with increased fatigue and decreased performance in athletes (endurance, strength, power output, etc). Several studies have shown that consuming adequate amounts of carbohydrates before, during, and after exercise may attenuate the increased fatigue and increase performance.9-14
It is worth noting that one such study concluded that "the rate of recovery is coupled with the rate of muscle glycogen replenishment and suggests that recovery supplements should be consumed to optimize muscle glycogen synthesis as well as fluid replacement." It can therefore be concluded that an adequate supply of carbohydrates is crucial for maintaining performance and for proper muscle recovery.
Fats
Fats are important molecules and are considered essential to ones survival. Indeed, fats are involved in many of the body's processes which are required for survival. Several key functions of fats in the human body are for energy storage and hormone synthesis. They are the body's preferred source of stored energy and the most efficient molecule for the body to burn. (in terms of energy yield per gram, 9kcals/gram).
The main hormone that fats impact which we are concerned with is testosterone. When calories are restricted, testosterone levels will drop, as the body will suppress its release of anabolic hormones in order to spare nutrients for oxidation (energy production). This makes perfect sense: the body senses it is "starving" and thus it represses it's anabolic hormones to prevent nutrients from being used to increase tissue mass and spares them for energy production.
That's the first hit against testosterone production. Drastically lowering your fat intake is another hit against testosterone production since fatty acids are the substrates for cholesterol synthesis and therefore are also the substrates for testosterone synthesis (cholesterol is converted to testosterone, among other things).
Unfortunately, fats are also easily stored as adipose tissue (body fat) So there must be some type of comprimise between ingesting enough fat for hormone maintenance (and subsequent muscle maintenance) and reducing fat intake enough to decrease body fat.
There has been some research done on the effects of dietary fat on testosterone. The answer to, "how much dietary fat is optimal" is difficult to decipher, as there are major differences in the designs of the performed studies. This makes it difficult to compare them to each other and come up with a "standard" answer.
Several studies concluded that diets low in fat (under 15% of total calories) significantly decreased testosterone levels while diets higher in fat (above 30% of total calories) increased serum testosterone levels.15,16 Rather than continuing with this discussion I will provide a link to an article which covers the subject quite nicely.
To simplify everything that I have said, it seems that one should not lower fat below 15% of daily calories unless they would like to face extreme testosterone deficiencies. Likewise, one should not increase fat to say 40% in order to increase testosterone.
Although fat increases testosterone to a degree, it is important to remember that testosterone is only a small piece of the larger puzzle. There are many other hormones and factors involved in building muscle other than just testosterone. By increasing fat to extremely high levels, there will be less "space" for carbohydrates and protein, both of which are very important for aforementioned reasons.
As with most things in life, moderation is key. In order to keep hormone production regular and fat burning in high gear, while allowing enough "space" to supply adequate carbohydrates and protein for muscle sparing purposes I do not recommend increasing fat above 30% of daily calories.
Part 3 the diet next
