How intermittent fasting affects your hormones

The benefits of intermittent fasting, or IF, have been well-documented. Indeed, the National Library of Medicine has logged over 6,000 trials and reviews on the subject since 2015, making it one of the most thoroughly-studied eating plans in recent years. While the dietary pattern is not without controversy, it has been shown to yield benefits like lower blood sugar, reduced body fat, improved heart health, and better focus and energy.

But how exactly does it create these benefits? One explanation is a process called autophagy, a self-cleaning process in which the body clears out old and damaged cells to make way for newer, healthier ones. Another explanation lies in the potential benefits that intermittent fasting can have on your hormones.

That said, not all of the effects that IF has on your hormones are positive. Read on for two plus sides and one negative consequence. Being aware of all of the possible effects of any diet can help you make a more informed decision for you.

Before people began using intermittent fasting for the weight loss, energy and brain power benefits, the protocol was initially developed to help patients reverse diabetes---because of the way it impacts insulin. Insulin is the hormone that helps your body utilize sugar for energy. It’s produced when you consume foods that contain glucose, such as fruits, bread products, sweets and processed foods. But if you’re consuming too much glucose, the body can struggle to maintain adequate insulin production to process all of it, at which point your cells may stop responding to insulin. That’s when you end up with a condition known as insulin resistance. And when not dealt with, insulin resistance can progress to prediabetes and then type 2 diabetes since the body is unable to move glucose from the bloodstream into the cells.

When you take hours-long or days-long breaks from eating, as you would with intermittent fasting, you’re also giving your body breaks from processing glucose and producing insulin, preventing insulin resistance from developing. In a study published in the journal Cell Metabolism, obese men with prediabetes who restricted their eating window to eight hours a day and fasted for the remaining sixteen hours had noticeably lower insulin levels and improved insulin sensitivity (aka the ability to respond to and utilize insulin) after just five weeks.

Notably, it is possible to get in on some of the insulin-regulating perks regardless of the length of time spent in a fasted state. While harnessing the benefits of autophagy generally requires not eating for a minimum of 12 to 14 hours, even something as simple as skipping snacks and stretching out the time you leave between meals will allow your body time to improve insulin sensitivity .

The next hormone that is directly impacted by intermittent fasting is human growth hormone (HGH). Just as it sounds, HGH spurs growth---but it is also responsible for maintaining bone and muscle mass, among a few other roles. The problem is that while HGH levels are high in kids, adolescents and young adults, they start to drop as you age, roughly 15% every decade after your 30s, which can lead to bone and muscle loss, loss of muscle strength, and an increase in body fat.

Research has shown that fasting for sixteen hours or more at a time prompts the body to produce more HGH. That’s because by this point in a fast the body is forced to turn to fat stores to use as fuel. This switch signals to the body that you’re “starving” (even though you know you plan to eat again soon), so it takes action to protect itself, one of which is upping HGH production. By using this mechanism to your advantage you can actively combat the age-related drops in bone density and muscle mass that can lead to conditions like osteopenia, osteoporosis, and sarcopenia---or even gain muscle, if you combine IF with strength-building exercise.

The only hitch with HGH is that you do need to take part in a slightly longer fast to get the benefits, such as alternate day, 5:2 fasting, or extended fasting. In a study from The Journal of Clinical Endocrinology and Metabolism, subjects who fasted for two days at a time saw a five-fold increase in HGH production.

You likely know cortisol as the primary stress hormone. Well, it turns out that going without food for an extended period of time can increase levels of cortisol. High cortisol levels are also linked with fat storage, which, if you’re trying to lose weight, probably isn’t the effect you were hoping for.

While it’s important to be aware of this potential downside of this eating pattern, there’s a reason that IF still has plenty of proponents. Here’s why: Despite the fact that cortisol typically prompts the body to hold onto fat, the absence of glucose to use for fuel during a fast forces the body to dip into its fat stores for energy, essentially overruling this negative effect of the stress hormone. Indeed, in a study in the American Journal of Clinical Nutrition, subjects who dropped from eating three meals a day to just one for several weeks experienced a 12% reduction in body fat mass.

Considering that approximately one in three American adults has prediabetes and everyone over 40 will experience declines in HGH, there’s a good chance these benefits of intermittent fasting may sound appealing to you. But one way to determine if it is the best method to help you get these health benefits---in addition to the many others IF can offer---is by using the Base Diet Test to find out if these are in fact the hormones you should be targeting in order to transform your health.

The test measures levels of hemoglobin A1c (HbA1c), or the amount of glucose attached to hemoglobin, the part of your red blood cells that transports oxygen around the body. While that may sound like a super specific thing to be measuring, it actually correlates almost directly to the amount of glucose in your bloodstream. If your HbA1c levels are lower than 5.7%, that’s a sign that your blood sugar levels are normal. But if your result is higher than 5.7%, it could be a sign of insulin resistance or prediabetes---and a result over 6.5% would prompt a type 2 diabetes diagnosis. HbA1c levels in that middle range mean that you have time to make diet and/or lifestyle changes to reverse your insulin resistance and intermittent fasting could be just the ticket to help you do that.

It also measures C-reactive protein (CRP), a protein produced by the liver in response to inflammation. If your CRP levels are high, it may be a sign of chronic inflammation or another chronic illness that needs to be addressed. Considering that intermittent fasting has been shown to reduce inflammation, high CRP levels may signal that this lifestyle intervention could be for you.

That said, intermittent fasting is not the only way to reduce insulin resistance and combat chronic inflammation. If restricting your eating to certain times of day or days of the week doesn’t sound appealing, you can try altering what you are eating instead of when. Cutting out processed foods and high-sugar foods while favoring fruits, vegetables, lean protein and fiber that don’t dump huge amounts of glucose into your bloodstream will help regulate insulin levels and improve your body’s ability to respond to the hormone. Filling your plate with those same fruits, vegetables and plant-based sources of protein and fiber will also help reduce body-wide inflammation.

There are also other ways to increase your HGH levels naturally, though intermittent fasting is one of the easier and more effective ones. These include supplementing with the amino acids arginine and GABA and doing high intensity exercise.

Plus, if you’re already dealing with adrenal fatigue or chronic stress, you may not want to risk the elevated cortisol levels that can result from going long stretches without eating. Instead, stress-reduction techniques, adaptogenic herbs and a balanced diet similar to the one mentioned above might be a better bet.

Research suggests that intermittent fasting is one way to optimize the hormones insulin and HGH, which can help prevent the development of conditions and illnesses like insulin resistance, prediabetes, type 2 diabetes, osteoporosis and sarcopenia. However, IF can also raise your cortisol levels and is not your only option to achieve these results. The Base Diet Test and the Base Stress Test can help you determine whether it is the best option for you.

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