Here's an excerpt from my book Minimal Medication on the interaction between intermittent fasting, or, if you are a teenager, just not eating all the time, and muscle growth.
The human body maintains lean body mass and even keeps muscles growing when food is scarce with the help of growth hormone. Although it is hard for constantly fed twenty-first century people to grasp the concept of muscles growing when they are not fed, the development of growth hormone conferred an enormous advantage for early people. After all, when is it that we actually need muscles to help us forage food? It's when we don't have food to eat, not when we do. The same genetic mechanism that conferred this paradoxical benefit on our ancestors so many years ago can help modern humans increase muscle mass today. Here is how it works. Growth hormone performs a number of beneficial functions in the human body. Growth hormone:
• Encourages the expansion of muscles by powering a process called sarcomere hypertrophy. The sarcomere is the tough protein-filled fiber in the muscle that allows it to expand and contract. Growth hormone helps it grow.
• Accelerates the process of lipolysis, the breakdown of fat inside fat cells so it can be “squeezed out” of the fat cell into the bloodstream and circulated to the muscles that use it for fuel.
• Increases the process of mineralization in bone, ensuring that calcium accumulates in bones rather than in atherosclerotic plaques in the linings of arteries.
• Reduces the liver's uptake of glucose. This keeps sugar in the bloodstream, counteracting hypoglycemia that might be caused by not getting enough food, and significantly reduces the liver's water weight.
• Protects the insulin-producing islet cells of the pancreas from “burnout” that can be caused by excessive exposure to sugar.
• Stimulates the immune system.
• Increases protein synthesis from amino acids that are already inside cells.
Growth hormone is made in the brain. More specifically, it is made in the pituitary gland. The pituitary “dumps” greatest amount of growth hormone into the bloodstream about an hour after the onset of sleep.
Not getting enough sleep may not interfere with the production of growth hormone in teenagers, but it is devastating to the production of the hormone in anyone over the age of about 20. If you are an adult and don't get enough sleep, your body does not make enough growth hormone. Isn’t that true for most of us?
There are many other influences that can increase the production of growth hormone.
• The more sex hormones (estradiol in women and testosterone in men) the body makes, the more growth hormone it makes. This is why boys and girls experience a growth spurt right after puberty, when their bodies start making unusually large amounts of sex hormones. Estrogen replacement therapy in women and testosterone injections or patches in men increase the production of growth hormone.
• The hunger hormone ghrelin stimulates the production of growth hormone. When you have gone without food long enough that your stomach is “yellin',” which is the effect of ghrelin, then your brain releases growth hormone. This is the way it makes sure that deprivation of food not only doesn't result in damage to your muscles but actually stimulates their growth.
• The hormone somatocrinin, which is also known as growth hormone releasing hormone, or a kind of “growth hormone hormone,” increases the production of growth hormone. Somatocrinin levels go up in response to ketogenic diets, diets in which the body is forced to burn fat.
• Sexual intercourse, vigorous exercise, and deep sleep also stimulate the pituitary gland to release more growth hormone.
There are also influences that interfere with the production of this vital hormone.
• High blood sugar levels impede the release of growth hormone. This is the reason some professional athletes complain (perhaps exaggerating, but not by a whole lot) that a single slice of cake can undo a whole week's training.
• Insulin-like growth hormone-1 (also known as IGF-1) can compete with growth hormone. IGF-1 increases sensitivity to insulin. This isn't always a bad thing, of course, especially if you are diabetic.
However, if you are trying to lose weight, increased sensitivity to insulin leads to increased storage of fat and decreased burning of fat.
• Stress hormones, part of a group of hormones known as the glucocorticoids, counteract the effects of growth hormone, especially in fat cells and in the liver.
The amount of growth hormone in your bloodstream triples during sleep. That's why sleep is so important to both burning fat and building muscle. Growth hormone concentrations in your bloodstream also triple while you exercise. But growth hormone concentrations in your bloodstream sextuple when you go without eating for 18 hours or more.
Not eating for 18 hours increases the muscle building and fat burning activity of your body by 600%, without growth hormone injections, without homeopathic growth hormone, without special foods, and without nutritional supplements. There actually is a point that if you continue to go without eating, whether intentionally or unintentionally, your body begins to break down muscles to release amino acids for tissue repair. That happens when you haven't eaten anything for about 72 hours. But if you simply manage to “stretch” your fast from overnight to eating brunch instead of breakfast, you give your body a break in which it can burn fat and build muscle.
Growth hormone is the only anabolic, muscle-building hormone that is activated by fasting. This is something volunteers for a starvation study revealed to the world. (This study was conducted by the US Army at the beginning of World War II to find out what would happen when soldiers were cut off from food supplies. Unlike the Nazis, the US Army used actual volunteers. ) When the volunteers were given a drug that blocks growth hormone, fasting actually breaks down muscle. That’s because the body breaks down protein into amino acids that the liver turns into glucose to be burned as fuel. (This process also releases urea, which would be highly acidifying, except that we have a God-given natural process that can defeat acidity several different ways. ) But when you fast, especially if you also get enough sleep, and have healthy levels of estrogen or testosterone, and you avoid stress, fasting changes your hormone levels so that your body actually builds new muscle instead of breaking it down. To repeat, fasting under appropriate conditions builds muscle.
Some people, however, don't get the full benefits of growth hormone at first. You probably can guess what the problem is.
People who have excessive body fat, especially people who have excessive abdominal (belly) don't get the full benefit of growth hormone. Even worse, just the act of overeating, even when you aren’t fat, can suppress the pituitary gland's release of growth hormone. One clinical study found that people who eat 4,000 calories per day for three days suppress 80% of their pituitary's production of growth hormone.
Boosting the production of growth hormone, if you are obese, requires losing fat. And losing fat, as we mentioned earlier, requires burning fat—a process that just can't happen while your fat cells are storing fat. To turn on the benefits of growth hormone, you have to turn off your appetite, at least long enough for your body to go into fat-burning mode. And that's simply not possible if you eat all the time.
Growth hormone is so incredibly useful in restoring and maintaining human health that it might seem logical just to skip the hard work of fasting and to take growth hormone injections. (Homeopathic growth hormone, we have to report, simply does not have the same effect. ) Growth hormone shots are pricey, usually about $2500 per month, and not covered by insurance in any country without a medical diagnosis of growth hormone deficiency. But if you have $30,000 a year lying around that you can spend for growth hormone shots, why not?
The reason that injected growth hormone does not work as well as growth hormone made by the body itself is that the brain's release of natural growth hormone is “pulsed,” whereas the growth hormone levels in people who take injections are constant. When you take growth hormone injections, your muscles burn fat all day long. They don't have any kind of metabolic incentive to become more sensitive to insulin to take glucose out of your bloodstream, so your blood sugar levels climb. Ironically, the effect of high blood sugar levels, over time, is even higher blood sugar levels, as the muscles become less and less sensitive to insulin. All the detrimental effects of pre-diabetes and even full-blown type 2 diabetes may follow.
Most people find it easier just to quit eating, pardon the pun, cold turkey for a short time than to try to eat less. We all tend to minimize our memories of what we eat. If you aren't restricting your calories by eating pre-packaged meals that someone else prepares, preferably someone who has a degree in dietetics or clinical nutrition and can guarantee calorie counts, then you are probably eating more than you think unless you eat nothing at all. And if you nibble your way through weight loss, your body never gets the fat-burning benefits of growth hormone.