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April 28, 2019
Ian Spohn, ND

Time Restricted Eating

Growth hormone levels decline with age, and this decline is thought to mediate many of the untoward symptoms of aging.

Intermittent fasting is one of the most effective ways to naturally increase growth hormone levels and has been shown to have a variety of other health benefits, including weight loss, improved blood sugar control, reduced inflammation, and the ability to stimulate autophagy, the process by which the body regenerates itself at the cellular level.

Time-restricted eating, a popular intermittent fasting strategy, can be incorporated into most lifestyles with relative ease and is an excellent, natural way to support other treatments for optimizing growth hormone levels.

Time-restricted eating involves consuming the same amount of food but doing so only within a limited time frame each day, as opposed to the more typical pattern of three evenly spaced meals with snacks in between. The easiest pattern of time-restricted eating is 12:12, in which all meals and snacks must occur in a twelve-hour window. If you begin the day eating breakfast at 7:00 AM and discontinue snacking by 7:00 PM, then you are already doing this.

A far stricter version of this is the 20:4 approach, also known as the warrior diet, which requires twenty hours of fasting followed by four hours of eating each day. This can be very effective, but only if you’re the type of person who can comfortably consume an entire day’s worth of food in four hours. Most people have been successful with the 16:8 approach, which fits well into most lifestyles but still provides 16 hours of uninterrupted fasting each day.

Though fasting for spiritual or therapeutic reasons has been around longer than any of us, the concept of intermittent fasting really became popular in concert with the rise of the paleo diet.

The paleo diet challenged many long-held dogmas regarding what makes a food healthy and what therefore constitutes a healthy diet. In fact, once added sugars are removed from the top of the traditional food pyramid, the paleo diet essentially advocates turning it upside down. However, after using our ancestral diets as a basis for challenging what we eat, and with the rise of paleo snack bars, paleo diet shakes, and various other so-called paleo convenience foods, it became difficult for people on the paleo diet to avoid facing this next logical question—when and how often did humans evolve to eat? For in those Paleolithic times, adopted as the basis for patterning a healthy modern diet, there were no microwaves, snack bars, blenders, vending machines, refrigerators, fast food restaurants; in fact, there weren’t even grocery stores.

The idea of having convenient, almost immediate access to prepared foods, such that one can routinely consume three meals per day with ad libitum snacks in between, was surely as foreign to our Paleolithic ancestors as the enriched bleached flour, high fructose corn syrup, and partially hydrogenated soybean oil that usually form the basis of such meals. As an inevitable result of this realization, the concept of intermittent fasting grew popular, with the goal of replicating, at least to the degree which is practical for people in modern society, the feast or famine style of eating to which our Paleolithic ancestors likely evolved.

Hence, upon inverting the conventional wisdom with regard to what we should be eating, the inversion continued with the claim that skipping meals might actually be good for you, possibly even essential to health, and not bad for you as is commonly held. Scientific evidence, especially regarding the effects of fasting on growth hormone levels, seems to support this assertion.

If the claims about time-restricted eating are true, it would practically constitute the holy grail of all weight loss strategies—it burns fat while preserving lean mass, it favorably modifies all the medically desirable parameters associated with weight loss, it doesn’t require calorie restriction, and it allows you to keep eating almost anything you want.

The trick, it is claimed, is as simple as merely changing when you eat. As a relatively new concept, the research on time-restricted eating is limited, but studies have already come out demonstrating that it can lower blood sugar, improve insulin sensitivity, lower blood pressure, and even reduce markers of oxidative stress—a potent cause of aging. Many of the benefits of time-restricted eating seem to overlap with the beneficial effects of human growth hormone, and it may be the case that time-restricted eating works precisely because it leads to naturally higher growth hormone levels.

The research is very clear that the release of growth hormone will increase dramatically in response to fasting. Even fasting for one day has been shown to triple growth hormone levels. The key to understanding this pertains to the actual fate of growth hormone in the body. Growth hormone never reaches a steady state in the blood; rather, it is released in a pulsatile manner as short-lived bursts. The liver metabolizes growth hormone very efficiently, quickly removing it from the blood, but in response to it, releases another hormone called insulin-like growth factor 1 (IGF-1), so-named due to its structural similarity with insulin. IGF-1 is then responsible for mediating all of growth hormone’s desirable effects.

Studies that assessed growth hormone levels in fasted subjects have concluded that these bursts can occur as often as every 90 minutes, and while short-lived, this repeated stimulation produces cumulative effects.

In normal subjects eating three meals per day, however, it was found that the majority of these bursts are blunted and may even disappear altogether, making it appear as though growth hormone is only being secreted at night—in other words, the only prolonged time frame during which normal individuals are not eating. The reason for this is very plain and provides the key to the ingenious theory of time-restricted eating: insulin antagonizes the release of growth hormone.

As it turns out, it’s not really true to say that fasting increases growth hormone levels—it’s more accurate to simply say that eating reduces growth hormone levels by temporarily shutting down its rhythmic release entirely. This is because eating a meal will always result in a surge of insulin. This surge will be greater if the meal contains a lot of carbohydrates, but even the most hardcore ketogenic diet will still result in some insulin secretion following every meal. It is easy to understand why the body wouldn’t want both insulin and growth hormone around at the same time.

They are structurally similar enough that IGF-1, which mediates the ultimate effects of growth hormone, will bind to insulin receptors, resulting in a lowering of blood sugar. This is in fact believed to be one of the reasons why intermittent fasting helps to lower blood sugar levels. But you wouldn’t want to have both of these hormones around at the same time, as this could lower blood sugar levels too far. So every time the body secretes insulin (i.e., every time you eat a meal), it temporarily halts the pituitary’s release of growth hormone, interrupting its normal rhythm until insulin levels drop back down to baseline.

So theoretically, if your body never secreted insulin then you would benefit from growth hormone all the time. But insulin is inevitably released every time you eat, and of course you cannot avoid eating as an effective long-term strategy. Indeed, while short fasts up to a few days will increase both the amplitude and frequency of growth hormone secretion, fasting any longer than this will actually have the opposite effect, as the body enters starvation mode. Growth hormone stimulates cells to grow and regenerate, which of course requires they have an adequate supply of nutrients.

Since eating leads to an insulin spike and since insulin temporarily stunts growth hormone release, the trick to maximizing growth hormone levels would seem to be this: to consume the maximum quantity of nutrition with the fewest number of insulin spikes, or in other words, the fewest number of meals.

This resembles the feast or famine dietary pattern to which we likely evolved, and in a modern context, this is exactly what time-restricted eating does.

It’s tempting to demonize insulin, given its association with weight gain and diabetes. Also, as long as the body remains under insulin’s influence, it cannot be under the fat-burning, muscle-building, cell-regenerating influence of growth hormone. But everyone needs to eat at some point, and it’s important to remember that insulin is merely a natural product produced and in fact required by the body.

As a hormone, all insulin really does is send a message to the body’s cells that tells them to store energy.

The related hormone IGF-1, made by the liver in response to growth hormone, basically tells the body’s cells to grow, repair, strengthen, and regenerate, which of course they cannot do without an adequate store of energy and nutrients. Here is one way to compare the actions of insulin and IGF-1: insulin tells cells to store energy, IGF-1 tells cells to utilize stored energy for growth and regeneration. It should be clear that without occasional bursts of insulin, cells will lack the raw materials to optimize their response to growth hormone.

The real logic behind intermittent fasting is to essentially separate the antagonistic actions of insulin and IGF-1, and to use them in harmonious balance instead of allowing them to inhibit each other.

Remember that growth hormone is being made constantly and is capable of being released all the time, except of course when insulin is around. If insulin is around all the time, i.e., if you’re eating frequently throughout the day, you’ll never develop any kind of significant growth hormone activity, except perhaps for a short time while you’re asleep.

Time-restricted eating, on the other hand, produces a daily rhythm featuring short bursts of eating to stimulate insulin and prime the cells with energy, followed by a period of fasting in which growth hormone will stimulate cells to make use of that energy for growth and regeneration, instead of merely storing it as fat. Since you (or your patients) will be fasting every day, the body’s natural production of growth hormone will be increased every day, and as long as adequate nutrition and calories are consumed during the time-restricted window, this elevated growth hormone production can be maintained indefinitely.


Any homeopathic claims are based on traditional homeopathic practice, not accepted medical evidence. Not FDA evaluated.

These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.