Intermittent fasting is a very polarizing subject these days.



Some believe it is the absolute healthiest thing you can do, while others say it is a great way to be tired and miserable.



And they can both be right.



So let's break down the benefits of intermittent fasting, and discuss who fasting may not be ideal for.



Many people do not feel hungry early in the morning. Intermittent fasting feels natural to them and they often do it unconsciously. This may have something to do with the "dawn phenomenon".


The Dawn Phenomenon


In the morning, we are woken up by various hormones rising, including adrenaline and cortisol. Cortisol stimulates the liver to release glucose for energy.



These hormones prepare the body to get moving, not to sit down and relax with a meal. Eating soon after waking will add to this rise in blood sugar, whereas fasting will allow that glucose to be “burned”.


Those who experience a larger Dawn Phenomenon, i.e. their blood sugar rises higher than it should, may experience more hunger and thirst in the morning than those with less of a spike. They may also feel nauseous and tired, among other possible symptoms.


For those with healthy blood sugar regulation, a small amount of insulin will be released to bring blood sugar levels back down. For those with insulin resistance/prediabetes or type 2 diabetes, they may not be able to produce enough insulin to bring the blood sugar levels back down and instead it will be stored- in the liver, muscles, and as fat tissue.


The Benefits of Fasting


Fasting has been shown to support healthy weight loss without muscle loss, reduce cholesterol, improve brain function, and more.



Fasting is a very effective way to eliminate insulin resistance and achieve lasting weight loss.



Glucose stores last about 24 hours. After they are depleted, fat stores are used for energy- a state called ketosis. Additionally, growth hormone and adrenaline increase to maintain muscle mass and metabolism. Note that this does not happen in calorie-reduced diets. In low-calorie diets (never reaching ketosis), metabolism actually slows.



Fasting also puts the body in a state of autophagy, or “self-eating”- the body “eats” it’s bad cells that are contributing to inflammation and aren’t sensitive to hormones, and stimulates new stem cells to be produced. This can occur in as little as 15-hour fasts. Autophagy can be a useful tool for most health concerns and chronic diseases.



Low-carb and low-calorie diets only work short-term because the body adapts. It then starts to hold onto fat as a safety mechanism by blunting insulin receptors (i.e. causing insulin resistance!). Intermittent fasting and feasting keeps metabolism up and prevents weight loss plateaus. In Western culture, we are always feasting, never giving our bodies time to “clean up”. It is beneficial to have periodic times of feast to “wake up” the cells and their receptors.


Who Should Not Fast?


First of all, everyone fasts.



When we are sleeping, we are fasting. Intermittent fasting can be as simple as waiting one hour past the typical time that you would have breakfast, or not snacking past a certain time after dinner.



As fasts increase in length, they of course get harder, and are more likely to pose some risks.



Certain populations like kids and pregnant people have high requirements for calories and nutrients, and intermittent fasting might make it hard for them to fulfill their nutrient needs.


Intermittent Fasting is Not Starving


Now, it's important to remember that intermittent fasting is time-restricted eating, NOT calorie restriction.



But often, when people attempt intermittent fasting, they simply omit a meal or two from their day, without replacing those calories and nutrients during their eating window. This is likely why many people don't feel well, experience low energy, brain fog, and other symptoms.


The Effect of Fasting on Cortisol and Thyroid Hormone


During a fast, thyroid hormones decrease but adrenaline rises to maintain metabolism. And remember that fasting should always be followed by feasting, to prevent long-term lowering of metabolism seen in low-calorie diets.



You may have heard that fasting or reducing carbohydrate intake is not safe for the thyroid gland because it needs glucose to function. Glucose is not an essential nutrient; though our cells need glucose as an energy source, the body can make it on its own.



Those with the autoimmune disease Hashimoto’s thyroiditis may benefit from intermittent fasting, as hyper-reactive white blood cells drop and normal ones are created through the process of autophagy that we discussed before.



However, fasting can be problematic for some people with thyroid dysfunction, especially if there is a concurrent cortisol problem since fasting can stress the adrenal glands. Imbalanced cortisol levels (high or low) can disrupt thyroid hormone production.



This is why it is essential to manage cortisol levels, stress, and sleep while working on blood sugar and insulin levels. Those who are under significant stress, and/or suffer from anxiety, might do better to start with shorter fasts until they feel more stable.



Curious if intermittent fasting should be a part of your health plan? Let's chat!