Amy Shah, M.D., is a nationally renowned functional medicine doctor and trained ayurvedic practitioner. She’s also one of the lauded instructors in our first-of-its-kind Advanced Functional Nutrition Program, where we bring the best minds in nutrition together to dive deep into the healing power of food. You can find out more about Dr. Shah, the rest of the faculty (including groundbreaking doctors like Mark Hyman and Frank Lipman), and this revolutionary training here.
Over the last thousand years, our meals have gotten closer and closer together to the point where many people eat late at night and then eat breakfast first thing when they wake up in the morning.
This isn't how our bodies were designed to eat, and it's not what will promote optimal functioning.
From studies it is likely that many of our genes were selected during the late Paleolithic era (50,000 to 10,000 B.C.), during a time when humans existed as hunter-gatherers. At that time there were no guarantees of finding food, resulting in mixed periods of feast and famine.
With that in mind, it makes sense that taking a break from eating is good for our hormones but also our digestion, brains, and more. Currently, we are dealing with many diseases prompted by hormonal disruption such as diabetes, cardiac disease, autoimmune diseases, obesity, even cancer. Intermittent fasting seems to be a promising tool in preventing and treating disease.
What is intermittent fasting?
Intermittent fasting simply means taking a break between meals. This break can be similar to normal evenings spent not eating (not eating from 7 p.m. to 7 a.m. would be a 12-hour fast), slightly longer (7 p.m. to 11 a.m. is a 16-hour fast), and even several days. The type of fasting you practice depends on your individual body and preferences, in addition to what you're trying to accomplish. Many people prefer to simply skip breakfast, stretching out the period between dinner and their next meal, while others want the more extreme challenge of a multiday experience.
What hormones are affected by intermittent fasting?
Insulin seems to respond extremely well to intermittent fasting. Although many of the initial studies on the benefits of fasting were done on animals, a recent human study showed improvement in insulin sensitivity. When you eat glucose and insulin levels spike, it triggers a number of actions in your body, such as helping cells in the liver, skeletal muscles, and fat tissue to absorb glucose from the blood. Once that is fulfilled, insulin signals the liver to take up glucose and store it as glycogen (stored energy) and then fat. If you keep spiking that insulin, you can get insulin resistance (cells get less sensitive to insulin) and in turn get inflammation, increased fat storage. By giving your body a "break" from the spikes, intermittent fasting allows the body to have better insulin sensitivity when you do eat.
Another hormone that is dramatically improved with fasting is growth hormone: the fountain of youth hormone! Growth hormone helps preserve muscles and bone density and helps use fats for fuel. It also makes us look and feel "youthful." Some athletes (illegally!) use it for muscle growth and athletic performance. Unfortunately, growth hormone secretion decreases steadily with age. One of the most potent stimuli to growth hormone secretion is fasting. Over a five-day fasting period, growth hormone secretion more than doubles.
How to avoid feeling starving and making your hormone imbalance worse.
Knowing all the potential health benefits of intermittent fasting, I was eager to give it a try. Unfortunately, I failed miserably at my first attempt. The first day I didn't eat enough and couldn’t sleep because of extreme hunger pangs. The next day, tired and cranky, I overate with the voraciousness of a starved animal. That’s when my hunger and hormone roller coaster began. Of course, I’m not a quitter, and I thought that to get the full effect, you had to fast every single day. It took seven days of this roller coaster before I finally quit.
I made the very mistake I warn people against—I was too aggressive. If you're a woman and on the thinner side, you need to be careful not to throw your hormones out of whack. Put simply, women are extremely sensitive to signals of external starvation, and if the body senses that it is being starved, it will ramp up production of the hunger hormones leptin and ghrelin. When women experience insatiable hunger after undereating, they are actually experiencing the increased production of these hormones. It’s the female body’s way of protecting a potential fetus—even when a woman is not pregnant.
In animal studies, after two weeks of intermittent fasting, female rats stopped having menstrual cycles and their ovaries shrunk while experiencing more insomnia than their male counterparts (though the male rats did experience lower testosterone production). The take-away? For everyone—but especially women—it's best to go low and slow. Start with a 12-hour fast two days a week, and if that's fine, work up from there, adding an hour at a time. Listen to your body, and remember, stress undoes any positive effects, so do only what's absolutely comfortable.
If you want to learn more about hormones from Dr. Shah, be sure to check out mbg's new functional nutrition program!