The Hormonal Benefits of Intermittent Fasting

IFEarlier, we introduced the concept of intermittent fasting, a dietary pattern that is gaining popularity because of its potential to aid fat loss. By limiting a day’s calories to a 4-to-8-hour span and fasting the rest of the day (for many, this works out to skipping breakfast and dessert), it is possible to influence insulin values and sensitivity within the body, as well as help deplete glucose and glycogen, meaning body fat stores are targeted for energy.

However, research suggests that even muscle-builders stand to benefit from intermittent fasting, and it’s all because fasted states tend to produce more growth hormone — and the studies have shown this for quite a long time.

A Washington University study done in the 1960s asserts what we still know today as a gospel truth: You secrete more growth hormone (GH) while you sleep. Further, the study shows that going to bed in a fasted state — your body really favors burning fat here, especially when there is a shortage of blood sugar or glycogen stored in the muscles — further primes the metabolism for anabolic activity (again, all going back to the pancreas and insulin).

Now, add in resistance training to this mix, and you’re creating a perfect storm of sorts: The fasted state you stay in until right after your training session increases the production of GH. The fasted sleep you got the night before this has done it even more. And the protein-and-carb-heavy meal you consume immediately after training pretty much throws the whole muscle-building, fat-burning process into motion by signaling to the pancreas to release anabolic insulin, which carries glycogen to your muscles for immediate recovery — and, because of your previously fasted state, there isn’t left-over blood sugar waiting to be used or burned, so your body doesn’t need to store it as fat.

A 2003 Sports Medicine study explains the benefits of exercise on growth hormone production:

Resistance training results in a significant EIGR (Exercise-Induced GRowth hormone). Evidence suggests that load and frequency are determining factors in the regulation of hGH (human growth hormone) secretion. Despite the significant EIGR induced by resistance training, much of the stimulus for protein synthesis has been attributed to insulin-like growth factor-1 with modest contributions from the hGH-GH receptor interaction on the cell membrane. (Source)

In short, you’re bolstering your GH production four ways: Sleep, fasting, exercise and timed eating. And the hunger that you might first experience when adopting intermittent fasting subsides, fast — remember, we’re a species that spent centuries not knowing from where or when our next meal was coming from. We were hungry a lot. Our bodies produce a substance called Ghrelin that basically decides when we feel hungry, for how long, and what to do with metabolic energy. And, as you might’ve guessed from our theme here, it plays a role in signaling the release of growth hormone when we do eat. Its name is cutely derived: (Growth Hormone Release-Inducing = Ghrelin)

Once your body knows (yes, your body learns, and very quickly) that you’re not going to be eating every three hours, and that a fasting period is coming, hunger side effects like crankiness and morning irritability from skipping breakfast will fade. Ghrelin will make sure of that.

The bottom line on intermittent fasting, as far as hormones go, is that research strongly indicates it can provide a significantly anabolic, fat-burning environment based on the body’s hormonal responses to the changes it would go through. And who doesn’t want that?

Intermittent Fasting: Is It For You?

Most of what we know to be good dietary practice revolves around a few tenets that we’ve hammered home: Eat six small meals a day; eat protein with every meal; do not let yourself go into “starvation mode,” etc. One dietary trend that is gaining traction, however, throws all of these to the wind — and people are getting results with it.

It’s intermittent fasting, the most popular form of which is a “feast and fast” mode that gives you a specific time period in which you can eat, followed by another in which you don’t. There are three major components to intermittent fasting that, when we consider their role in fitness and dietary nutrition, become very interesting: insulin sensitivity, hormone production and energy storage. This article is meant to focus on the role of insulin sensitivity and the possible benefits of intermittent fasting.

Intermittent fasting: It's good enough for Wolverine. Is it good enough for you?

Intermittent fasting: It’s good enough for Wolverine. Is it good enough for you?

Anyone with a famous body do it? Yep.

What we know about how the pancreas reacts in different stages can clue us in to why intermittent fasting very well could be a viable dietary strategy. Everything we’ve come to know about the role of insulin, not only in fat loss but in muscle gain and even in diabetes, suggests that we probably don’t need to be providing blood sugar to our bodies every three hours; true enough, most people following a nutritious diet tend to stay away from the frequent carbohydrates that are eventually turned into glucose anyway. But, large calorie spikes, carb or not, can indeed cause jolts of insulin to help move and transport all those nutrients — the question is, how do we 1) take advantage of insulin, which is a natural anabolic hormone, and 2), keep our bodies sensitive to it so that we get those advantages more frequently?

Intermittent fasting — in our context, eating only in a four-to-eight-hour window immediately following exercise and eating no other calories outside of it — helps promote insulin sensitivity. When your organs and tissues are already saturated with stored glucose, ready to be used as energy at a moment’s notice, and you eat a meal, the pancreas still secretes insulin. When insulin saturates the body, though, it remains in the bloodstream, and your body becomes more and more resistant to its effects — continuing down this road of constant insulin presence in the blood leads to diabetes. Those who exercise frequently use this stored glucose as fuel, which means that when they eat, the insulin has a place to go, a role to play, instead of settling in the bloodstream. That concept is one of the main ones behind intermittent fasting: by diminishing the frequent supply of glucose in the body, you can encourage your body to instead turn to stored body fat for energy and at the same time keep it sensitive to insulin.

The Journal of Applied Physiology took a good look at this very topic, and the basic premise of its findings: the body responds to insulin the most after a period of fasting. Your blood sugar levels deplete as you sleep, and do so even more as you fast (and, as we’ll explain later this week, do so even more as you train). This can set you up for massive anabolic boosts if you choose healthy foods and time your feast periods properly (i.e., right after your workouts), and also add another major benefit: body fat loss.