*Sorry if there's formatting issues; this article is pasted directly from the book and blogger doesn't always play nice.
Metabolism
When most people use the word metabolism, they’re usually referring to the body’s rate or ability to burn fat, which is incorrect. Metabolism describes the full scope of how, why, where, and how fast tissue is either oxidized (burned), synthesized (built), or stored (as fat or glycogen). Metabolism can be split into two sides of the same coin: anabolism and catabolism.
Anabolism means tissue creating, a state in which smaller base components are aggregated through various mechanism to build new tissue. This is true whether the body is constructing new muscle (protein synthesis/proteogenesis), storing new fat (lipogenesis), or depositing glycogen into muscle tissue (glycogenesis).
Catabolism means tissue destroying, a state in which larger components are broken down into constituent pieces and oxidized (burned) or otherwise consumed. This is true whether the body is oxidizing blood sugar or stored sugar (glycolysis, glycogenolysis), muscle tissue (protein degradation/proteolysis), or fat (lipolysis).
A lot of trainees think that they’re binarily either catabolic and burning all types of tissue, or anabolic and packing on all kinds of tissue across the board. In a way, that’s correct; it’s physically impossible to burn fat and build muscle at any one given time. That being said, there’s a lot of factors that influence what kind of tissue is burned during catabolism, and what kind of tissue is built or stored in anabolism. This is known as calorie partitioning.
Calorie Partitioning
Why is it that one person can overeat, gain no muscle and put on fat, while another can eat the same amount and have it all go towards muscle mass? You might say, “Well, it’s obviously because some people exercise and eat clean.” That’s a true enough statement when comparing a sedentary, diet unconcerned person to a training, diet conscious one, but what about comparing changes between very similar individuals?
Consider two men or women of the same height, weight, strength/athleticism, and body fat percentage. They eat the exact same calorie deficit and do the same training protocol. Both lose 15 lbs of weight. Why is it that one of them has lost 14.5 lbs of fat and .5 lbs of muscle, while the other has lost 11 lbs of fat and 4 lbs of muscle? What about if we reverse the scenario so the trainees eat a calorie surplus, gain 15 lbs, and have a similar disparity between muscle and fat gain? What accounts for the differences?
The answer comes down to calorie partitioning. During a caloric surplus, something(s) in our body direct calories to either get stored as fat or used to build muscle. During a calorie deficit, something(s) pull resources from fat stores or from lean body mass. So what controls how the body uses energy?
A good deal of it is governed by genetics. Ancestry plays a large role in genetic predisposition to store fat or build muscle. Different heritages have deeply ingrained genetic traits which allow them to thrive in their native regions. We can’t change genetic calorie partitioning anymore than we can tell our genetics to make us taller. Understand that it plays a role, but is ultimately out of our hands.
Of course, there’s always drugs. Juicing can also have a prominent effect on calorie partitioning. It’s why bodybuilders can eat a caloric surplus, take a few injections into their biceps, and have all those calories go directly towards building bulging, tumescent guns. I won’t dive too much into the topic of performance enhancing drugs; just know that they generally come with severe consequences and I would never advocate their use to anyone, especially if they aren’t in a position to make millions off said performance.
So what does that leave us? How can we direct our body to partition calories in a way that’s beneficial to our goals? The answer is manipulation of metabolism through hormonal response.
Hormones manage the processes of fat loss/gain and muscle loss/gain almost entirely. The intricate balance of anabolic and catabolic hormones in our bodies dictates overall metabolism. Assuming that any sane trainee would prefer optimal fat loss and muscle gain, there are some hormones we’d like high levels of, and some we’d like to keep low (or at least within normal ranges). Take a look at the following:
Effects of Prominent Metabolic Hormones
Hormone
|
Insulin
|
Growth Hormone
|
Testosterone
|
Chronic Cortisol
|
Glucagon
|
Chronic Adrenaline
|
Anabolic
|
X
|
X
|
X
| |||
Catabolic
|
X
|
X
|
X
| |||
Stimulates fat gain
|
X
| |||||
Inhibits fat gain
|
X
|
X
| ||||
Stimulates fat burn
|
X
|
X
|
X
|
X
| ||
Inhibits fat burn
|
X
| |||||
Stimulates muscle gain
|
X
|
X
|
X
|
X
| ||
Inhibits muscle gain
|
X
| |||||
Stimulates muscle loss
|
X
| |||||
Inhibits muscle loss
|
X
|
X
|
X
|
X
| ||
Stimulates glycogen storing
|
X
| |||||
Inhibits Glycogen Storing
|
X
|
X
|
Stimulation and Inhibition of Metabolic Hormones
Hormone
|
Stimulated by
|
Inhibited by
|
Insulin
|
Eating-carbs more so than protein, hyperglycemia
|
Glucagon, catecholamines, hypoglycemia
|
Growth Hormone
|
Deep sleep, heavy training, ghrelin, intermittent fasting
|
Hyperglycemia, sleep deprivation, cortisol, chronic stress
|
Testosterone
|
Heavy training, deep sleep, ensuring no vit-d, magnesium, or zinc deficiencies, dietary fats
|
Aging, sleep deprivation, cortisol, chronic stress
|
Cortisol
|
Acute & chronic stress, sleep deprivation, prolonged/severe calorie deficit, too much exercise, prolonged aerobics
|
Relaxation, deep sleep, sufficient calorie intake, laughing and humor
|
Glucagon
|
Hypoglycemia, catecholamines, cholecystokinin,
|
Insulin, growth hormone, elevated free fatty acid/ketone bodies in blood
|
Adrenaline (catecholamines)
|
Acute and chronic stress, sleep deprivation, excess calorie deficit
|
Relaxation, deep sleep, sufficient calorie intake
|
This is an admittedly simplified outlook on hormonal response, but it’ll work just fine for our purposes. There’s hundreds of various hormones that play smaller roles in both short and long term metabolism. Some searching around will reveal interesting discussions on other hormones such as cholecystokinin, peptide YY, other glucocorticoids, IGF-1, cAMP, estrogen, tyrosine-based thyroid hormones, and countless others that play a role in metabolism.
It’s important to be clear that the “negative” catabolic hormones are only problematic when they’re chronically elevated. Adrenaline and cortisol are both necessary hormones and have important physiological roles in the body; they only become negative when stress, lack of recovery, too much exercise, too severe a calorie restriction, or other triggers cause them to be chronically high. Likewise, the “positive” anabolic hormones cease to be healthy when they’re artificially elevated.
How does one actually set a program up to optimally influence these hormones? You'll have to read the book to find out!
