4 surprising ways how intermittent fasting affect glucose levels

Intermittent fasting (IF) is the intentional restriction of meal times to maximise health. While media coverage often portrays IF as the latest fad diet, it is neither a fleeting trend nor a restrictive eating plan. 

IF has roots that stretch back centuries, standing apart from modern diets with their often bizarre and arbitrary rules. In fact, nutrition and fasting are deeply intertwined at a biological level.

Fasting.

Think of intermittent fasting not as a diet but as a lifestyle revolution. It’s similar to limiting your kids’ screen time to protect their developing brains from the endless allure of YouTube. 

Just as these limits nurture healthier habits in children, IF cultivates a more balanced approach to eating, allowing our body to thrive without constant snacking. 

A glance at recent statistics reveals the growing popularity of intermittent fasting (IF).

  • In 2022, a survey found that 80.1% of people worldwide were aware of intermittent fasting. 
  • 23% of individuals reported experiencing better sleep after practising IF. 
  • On Instagram, there are 52 posts per hour dedicated to intermittent fasting. 
  • 40 global studies have demonstrated that IF promotes significant weight loss. 
  • It is particularly popular among middle-aged individuals. 
  • The market for intermittent fasting apps is projected to grow at a compound annual growth rate (CAGR) of 15.7% from 2023 to 2030. 
  • In the United States, 10% of adults aged 18 to 80 use intermittent fasting as a dietary strategy.

By embracing the natural rhythms of hunger and satiety, IF offers a practical, sustainable path to better health and well-being.

This Avea article delves into how intermittent fasting influences glucose levels, exploring the underlying mechanisms, potential benefits, and practical considerations for incorporating IF into your lifestyle.

What is intermittent fasting?

Intermittent fasting (IF) is an eating pattern that alternates between periods of eating and fasting. Unlike traditional diets, IF focuses on when you eat rather than what you eat. 

There are several popular forms of IF:

  • 16:8 method: Involves fasting for 16 hours each day and eating all meals within an 8-hour window.
  • 5:2 method: Involves eating normally for five days of the week and consuming only 500–600 calories on the remaining two days.
  • Alternate-day fasting: Involves alternating between days of regular eating and days of fasting or very low calorie intake.
  • Eat-stop-eat: Involves a 24-hour fast once or twice a week.
  • Warrior diet: Involves eating small amounts of raw fruits and vegetables during the day and a large meal at night within a 4-hour window.

Learn how to perform the right type of fasting for yourself.

Fasting works differently at different stages of a woman’s menstrual cycle. If you want to understand how to reap your body’s potential, you have to start with (1) understanding when to fast, how to eat, and when to exercise during each phase of the menstrual cycle.

Discover how fasting in women differs – unveiling the 28-day cycles truths.

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Historical and cultural context

Fasting is not a new concept; it has been practised for centuries across various cultures and religions. 

Ancient Greeks, including Hippocrates, advocated fasting for health benefits. In many religious traditions, such as Islam, Christianity, Buddhism, and Hinduism, fasting is a spiritual practice that promotes discipline and self-control. 

These historical and cultural practices highlight fasting’s long-standing role in human health and spirituality, providing a foundation for modern IF’s resurgence as a lifestyle choice promoting overall well-being.

The science of glucose metabolism

1. Glucose basics: What is glucose?

Glucose is a simple sugar that serves as the primary source of energy for your body’s cells. It is obtained from the carbohydrates you consume, such as bread, rice, fruits, and vegetables. 

Once ingested, carbohydrates are broken down into glucose, which enters your bloodstream. 

This glucose is then transported to cells throughout your body to be used for energy, supporting vital functions like muscle contractions, brain activity, and cellular processes.

2. Insulin function: What does insulin do?

Insulin is a hormone produced by your pancreas that plays a crucial role in regulating your blood glucose levels. 

When you eat, and glucose enters your bloodstream, your pancreas releases insulin. Insulin facilitates the uptake of glucose into your cells, where it can be used for energy. 

It also signals your liver to store excess glucose as glycogen for later use. By promoting glucose uptake and storage, insulin helps maintain stable blood sugar levels and prevents hyperglycaemia (high blood sugar).

3. Glycogen storage: What is glycogen?

Your body stores excess glucose in your liver and muscles as glycogen. This storage form of glucose acts as an energy reserve that can be mobilised when your body needs extra fuel, such as during fasting or prolonged exercise. 

During fasting, blood glucose levels drop, prompting your pancreas to release another hormone called glucagon. 

Glucagon signals your liver to convert stored glycogen back into glucose and release it into the bloodstream, ensuring a steady supply of energy even when food intake is limited. 

This process helps maintain blood sugar levels and provides energy for vital functions until your next meal. 

How does intermittent fasting affect glucose levels?

Intermittent fasting (IF) exerts a profound impact on glucose regulation through various interconnected mechanisms. 

Beyond simply reducing calorie intake and promoting weight loss, IF influences how your body processes and utilises glucose. 

This section delves into the key mechanisms by which IF affects glucose levels, enhancing overall metabolic health. 

Let’s explore how your body can shift its energy utilisation from glucose to fat during fasting, how IF improves insulin sensitivity, and how reduced insulin levels contribute to glucose stability.

The human body has evolved into intricate and adaptive systems, finely tuned to survive periods of scarcity. 

Nature’s design is truly remarkable, and by harnessing the benefits of intermittent fasting, we can exploit these natural mechanisms to our advantage. 

In today’s world, where food is abundantly and frequently available, we have not evolved to cope with such constant consumption. Intermittent fasting can help us realign with our natural rhythms and promote optimal health.

1. Fasting improves energy utilisation

When you fast, your body undergoes a significant shift in energy utilisation. 

Initially, it uses glucose stored as glycogen in your liver and muscles. Once these glycogen stores are depleted, typically after 12–16 hours of fasting, your body begins to break down fat stores into fatty acids and ketones to use as alternative energy sources.

This metabolic switch from glucose to fat not only helps maintain energy levels but also promotes fat loss and improves metabolic health.

Humans didn’t evolve with the concept of “three square meals a day.” Our ancestors survived through cycles of feast and famine, without the convenience of modern food availability. 

This evolutionary background means our bodies are adept at storing nutrients during times of abundance and efficiently utilising those reserves during scarcity. 

Intermittent fasting mimics these natural feast and famine cycles, albeit on a smaller scale, training our bodies to smartly use their metabolic resources.

When your stomach is empty and your body needs energy, IF prompts it to metabolise fat reserves as nature intended. 

This process stabilises blood sugar levels, flattening peaks and preventing deep valleys. Sharp rises and falls in blood sugar levels are known as glucose spikes. 

As a result of constant glucose spikes, our cells lose their ability to process glucose efficiently. This is the start of many age-related diseases, let alone the wrinkles, saggy skin or other skin conditions.

Discover why glucose spikes are harmful.

Metabolic flexibility gained through IF reduces the side effects of hunger, so we are less likely to experience irritability or “hanger” when a meal is delayed.

This mechanism is one of the key reasons people are drawn to try IF. 

Systematic studies have shown a strong correlation between IF and weight loss, especially when combined with exercising [1], [2], [3], [4]

While results are highly promising, the field of intermittent fasting research is still relatively new, and more data is needed to definitively link IF with long-term weight management.

The promising start of these studies indicates the potential of IF in promoting weight loss and metabolic health, making it a compelling option for those seeking to enhance their well-being

2. Fasting improves insulin sensitivity

Certain studies show that Intermittent fasting can enhance insulin sensitivity, meaning it can make your cells become more responsive to insulin [5], [6].

With improved insulin sensitivity, this glucose uptake process becomes more efficient. Here’s how it works at the cellular level:

  • Insulin receptors: Each cell has insulin receptors on its surface. When insulin binds to these receptors, it signals your cell to allow glucose to enter. Enhanced insulin sensitivity means that these receptors are more effective at responding to insulin, allowing more glucose to be absorbed with less insulin required.
  • Glucose transporters: Inside your cell, glucose transporters (such as GLUT4 in muscle and fat cells) are activated by insulin to move to the cell surface and facilitate glucose entry. Improved insulin sensitivity increases the activity and number of these transporters, further boosting glucose uptake.
  • Reduced insulin resistance: Insulin resistance occurs when your cells become less responsive to insulin, requiring more insulin to manage blood sugar levels. This condition is a precursor to type 2 diabetes. By improving insulin sensitivity, IF helps prevent insulin resistance, reducing the risk of developing diabetes.

Discover our insulin resistance diet plan: 8 hacks for balancing your blood sugar levels!

3. Fasting reduces insulin levels

Fasting periods also result in reduced insulin levels. With fewer meals, your pancreas produces less insulin, allowing insulin levels to drop. 

Lower insulin levels are beneficial because they promote fat burning and prevent the body from storing excess glucose as fat. 

Besides, reduced insulin levels help maintain stable blood glucose levels, preventing the spikes and crashes associated with frequent eating. This stability is crucial for preventing metabolic disorders and promoting long-term health.

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4. Fasting decreases inflammation

IF influences several molecular pathways. For instance, it increases the activity of AMP-activated protein kinase (AMPK), a key regulator of energy balance, and reduce inflammation, which is often linked to insulin resistance.

Our body can become inflamed as a response to stressors, which can include not just germs or viruses, but also the process of metabolising food. 

Metabolising food is energy-intensive and generates oxidative stress, which can lead to inflammation if it becomes excessive. Learn more about oxidative stress and 5 simple ways to reduce it.

Oxidative stress hampers your body’s ability to detoxify and is the reason why supplements containing antioxidants are recommended.

Intermittent fasting acts as a natural antioxidant by reducing the frequency of eating, thereby limiting the oxidative stress associated with metabolism [7], [8], [9], [10]

This reduction in oxidative stress is crucial because chronic inflammation is linked to several diseases, including Alzheimer’s, Parkinson’s, and diabetes. 

By lowering inflammation through IF, we can reduce our susceptibility to these diseases and alleviate symptoms if they are already present.

IF’s ability to limit oxidative stress and inflammation not only supports better glucose regulation but also contributes to overall health.

By shifting energy utilisation, enhancing insulin sensitivity, reducing insulin levels and inflammation, intermittent fasting provides a multifaceted approach to regulating glucose levels and supporting metabolic health. 

These mechanisms contribute to the broad range of health benefits associated with intermittent fasting, making it a powerful tool for improving your overall well-being.

Health benefits of intermittent fasting on glucose levels

While the mechanisms of intermittent fasting (IF) explain how this practice affects our glucose metabolism on a cellular level, the practical health benefits offer a broader perspective on its impact. 

Juggling a demanding job, family responsibilities, and trying to stay healthy? It can feel overwhelming; we understand.

Understanding these benefits can help you appreciate the full scope of IF’s potential and incorporate it effectively into your busy lifestyle. 

Picture yourself with more stable energy throughout the day, fewer hunger pangs distracting you during meetings, and a clearer mind for making those tough decisions at work. 

By embracing IF, you can find a sustainable way to manage your health amidst the chaos, improving not just your glucose levels but your overall well-being.

So let’s dive right into the health benefits!

1. Stabilising glucose levels

Intermittent fasting helps you maintain stable blood sugar levels by reducing the frequency and magnitude of insulin spikes. 

By limiting meal times, IF ensures that your insulin levels remain lower for extended periods, which in turn helps your body utilise stored glucose more efficiently. 

This stability prevents the rapid blood sugar fluctuations that can lead to energy crashes, mood swings, and cravings, supporting your overall metabolic balance.

In the long run, stable glucose levels also reduce the risk of metabolic syndrome, a cluster of conditions that increase your risk of heart disease, stroke, and other health problems. 

Preventing rapid blood sugar fluctuations can also lower the risk of developing chronic inflammation, which is linked to numerous diseases such as cardiovascular disease, Alzheimer’s disease, and certain cancers.

2. Reducing insulin resistance

Another significant benefit of IF is its ability to improve insulin sensitivity. Enhanced insulin sensitivity means that your cells respond more effectively to insulin, allowing for better glucose uptake and utilisation. 

This improvement can prevent or manage insulin resistance, a precursor to type 2 diabetes. By making your body more efficient at processing glucose, IF helps you maintain long-term metabolic health and reduce the risk of diabetes.

3. Weight management and glucose control

Weight loss and body fat reduction are closely linked to better glucose regulation. Intermittent fasting promotes weight loss by encouraging your body to burn fat for energy during fasting periods. 

As your body fat decreases, insulin sensitivity improves, leading to more stable blood sugar levels. Effective weight management through IF not only supports your glucose control but also reduces the risk of metabolic disorders, contributing to your overall health and well-being.

4. Autophagy and cellular health

Autophagy, a natural cellular process activated during fasting, involves the removal and recycling of damaged cellular components. 

This process enhances your cellular health and function, indirectly supporting better glucose metabolism. 

By reducing oxidative stress and inflammation, autophagy contributes to more stable blood sugar levels. 

Promoting autophagy through intermittent fasting helps you maintain cellular resilience and optimal metabolic function.

Practical considerations and tips for fasting

1. Starting IF Safely

Before beginning intermittent fasting, it’s crucial to consult with a healthcare professional, especially if you have underlying health conditions or are taking medications. 

They can help tailor a fasting plan that suits your individual needs and ensure that it aligns with your health goals. Start with a gradual approach, such as the 16:8 method, to allow your body to adjust to the new eating pattern without causing undue stress.

Avoid intermittent fasting if you’re:

  1. Underweight or suffer from eating disorders: Intermittent fasting can exacerbate unhealthy eating patterns and is best avoided by those with a history of eating disorders or who are chronically underweight.
  2. Pregnant or breastfeeding: The caloric restriction of intermittent fasting can negatively impact fetal development and reduce the nutritional quality of breast milk.
  3. Experiencing chronic fatigue or burnout: Adding the stress of caloric restriction can overload the body’s stress tolerance, worsening chronic fatigue or burnout.
  4. Taking insulin therapy or hypoglycaemic medications: Intermittent fasting can affect blood sugar levels, so individuals on these medications should consult their doctor before starting an IF regimen.

2. Balancing diet during eating windows

To maximise the benefits of intermittent fasting, focus on consuming nutrient-dense, low-glycaemic foods during your eating windows. 

Incorporate plenty of vegetables, lean proteins, healthy fats, and whole grains to provide sustained energy and maintain stable blood sugar levels. 

Foods rich in fibre and protein can help keep you full longer and prevent overeating. 

Hydration is also key, so drink plenty of water throughout the day and include hydrating foods like fruits and vegetables.

3. Managing common challenges

Intermittent fasting can come with challenges such as hunger, energy dips, and social situations. 

To manage hunger, drink water or herbal teas, and stay busy to keep your mind off food. Eating balanced meals with adequate protein and fibre can also help curb hunger. 

For energy dips, ensure you’re getting enough sleep and consider light exercise, such as walking or stretching, to boost your energy levels. 

In social situations, plan ahead by informing friends and family about your fasting schedule and choosing restaurants or meals that fit your eating window.

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By Aishani Rajarai

Aishani Rajarai is a scientific writer and neuroscience enthusiast. She holds a BSc in biochemistry and cell biology, and a minor in medicinal chemistry and chemical biology. Her mission at Avea is to bring the science of longevity through blog posts, newsletters, podcasts, and social media content to the public, so people can live a healthier, longer, and happier life.

Aishani Rajarai is a scientific writer and neuroscience enthusiast. She holds a BSc in biochemistry and cell biology, and a minor in medicinal chemistry and chemical biology. Her mission at Avea is to bring the science of longevity through blog posts, newsletters, podcasts, and social media content to the public, so people can live a healthier, longer, and happier life.