Fasting is an ancient practice that has been around for centuries and is known to offer immense health benefits. However, fasting and calorie-restrictive diets are not very sustainable. Hence, they have been tweaked and modified to increase sustainability, resulting in concepts such as intermittent fasting. It is as efficient as calorie restriction with comparable results.

Good Metabolic Health is the absence of abnormalities in blood sugar levels, triglycerides, blood pressure levels and central obesity. Any irregularities in metabolism lead to changes in these levels leading to various disorders. Therefore, metabolic health is a significant factor for overall health and needs to be maintained. Intermittent fasting is one of the ways to boost your metabolism and keep your metabolic health.

Let’s understand intermittent fasting and how it helps boost metabolism. First, however, here is the disclaimer. Everyone is unique. For some, even those with Type 2 Diabetes, intermittent fasting may not work. That is why we strongly advise that you take advice from a nutritionist before you embark on this journey. When in doubt, it is good to wear a wearable device, like the HealthifyPRO 2.0 BIOS, which will help track blood glucose levels in real-time. It will also help you decide on the correct approach that you should take for your fasting and eating routines. Besides that, the coaches will assist you in making the right food choices.

Understanding Intermittent Fasting

Common Approaches to Intermittent Fasting

According to data, one can follow intermittent fasting in various ways. However, the most common methods of intermittent fasting involve three standard methods. The three intermittent fasting methods include time-restricted Feeding, alternate-day fasting and periodic fasting.

Time-restricted Feeding involves eating only for a certain number of hours each day, often establishing a consistent daily pattern of caloric intake within an 8–12 hour time window.

Alternate-day fasting involves alternating between a 24-hour “fast day” and a 24-hour non-fasting “feast day”. It is the strictest form of intermittent fasting because there are more weekly fasting days. It again gets subdivided into complete alternate-day fasting and modified alternate-day fasting. Complete alternate-day fasting does not allow any calories on a fast day. In contrast, modified alternate-day fasting allows up to 25% of daily calorie needs on fasting days instead of complete fasting. 

Periodic fasting or whole-day fasting involves any period of consecutive fasting of more than 24 hours. It is an extreme form of diet. The most common form of periodic fasting is a 5:2 diet with two fasting days per week. Only 25% of calorie consumption is allowed on fasting days. 

The HealthifyMe Note

Intermittent fasting, also known as Intermittent Energy Restriction, is an eating pattern involving the restriction of calories during a particular period. The basic premise involves periods of eating and fasting.

Intermittent Fasting and Calorie Restriction: The Difference

While entering into the discussion about intermittent fasting, it is essential to understand the difference between caloric restriction and intermittent fasting. Calorie restriction reduces total caloric intake while not compromising on the nutrition required. Also, this has consistently resulted in decreased body weight and increased longevity in many studies.

Short-term calorie restriction ( for about six months) has significantly improved multiple cardiovascular health, insulin sensitivity, and mitochondrial function. In addition, these physiological effects have improved weight and improved lipid profile. However, one cannot sustain continuous calorie restriction in itself for long periods. Intermittent fasting, on the other hand, refers to eating patterns that do not dictate the amount but the number of times you should consume food. It has a fixed duration and closely resembles circadian rhythm. 

The benefits of calorie restriction and intermittent fasting are similar. They have almost the same efficiency for improving lipid and glucose metabolism. In addition, they have been proven to be equally effective for weight loss and treating metabolic syndrome. 

Some studies claim the superiority of Intermittent Fasting over calorie restriction in reducing weight. Intermittent fasting is a great tool to improve metabolism and promote healthy weight loss with the same efficiency and greater sustainability.

Any abnormalities in metabolism can lead to metabolic syndrome. There are multiple individuals suffering from metabolic syndrome in the present-day world. Also, this might be due to disturbances in circadian rhythm and a sedentary lifestyle. It is also a widespread misconception that being skinny equals being healthy and having good metabolism. However, the truth cannot be farther. Lean individuals can still have insulin resistance or high levels of low-density cholesterol. 

According to data, Metabolic syndrome is a combination of metabolic abnormalities that lead to coronary artery disease and increased cardiovascular mortality. Central Obesity, hypertriglyceridemia, and hypertension are critical constituents of this syndrome. In addition, a sedentary lifestyle, higher processed food consumption, increased weight, and genetic predisposition contributes to this disease. Therefore, lifestyle modification and proper dietary habits can help treat and prevent this disease. Intermittent fasting is one of the ways to boost metabolism and avoid cardiovascular mortality. 

How Does Intermittent Fasting Improve Metabolism?

Circadian Rhythm 

Circadian rhythm is a regular sleep-wake cycle of an individual. This rhythm affects various body functions at the cellular level and overall metabolism. Metabolism of the body is slower during the night times while it is higher during the mornings. These circadian rhythms can negatively affect the body’s metabolism and lead to poor metabolic health outcomes. Poor metabolism may lead to metabolic syndrome, increased risk of diabetes, obesity, hypertriglyceridemia and hypertension. 

According to research, intermittent or time-restricted fasting dramatically reduces food consumption in the evening when the metabolism is low and subsequently improves diurnal oscillations. It helps the body re-establish proper metabolism, which further reduces body weight. 

Action on Gut Microbiota

Gut microbiota are known to be sensitive to circadian rhythms. According to data, Constant or chronic disturbances in gut flora can disrupt the microbiota and cause impairment in gastrointestinal function and metabolism. Impairment in the gut metabolism may lead to increased energy absorption and reduced energy expenditure. Also, this may lead to weight gain and obesity. Intermittent fasting by re-establishing also boosts the metabolic effects of gut microbiota.

Metabolic Endotoxemia is the phase of mild systemic inflammation due to the release of certain chemicals known as endotoxins after the death of bacteria. This mild inflammation interferes with the proper metabolism. However, intermittent fasting provides gut rest, reducing the gut permeability and preventing the leaking of these endotoxins into the circulation, thereby preventing inflammation.

Metabolic Switching

When talking about intermittent fasting and its effect on metabolism, it is essential to understand the basic physiology of glucose and lipid metabolism and the concept of “metabolic switching” that occurs during the fasting state. 

According to research, feeding and fasting follow a cycle with four stages: the fed state, the post-absorptive state/early fasting state, the fasting state and the starvation or long-term fast state. Glucose is the primary energy source for most tissues. After meals, glucose gets utilised for energy and excess is stored as fat in adipose tissue. After long periods of fasting, triglycerides from adipose tissue get converted into fatty acids and glycerol, which get used for energy. The liver then converts these fatty acids into ketone bodies, which become a significant energy source during fasting.

Normal consumption of meals generally only has two stages: fed state and post-absorptive state. However, in intermittent fasting, an individual often goes through all the states: fed state, post-absorptive, and fasting states. Insulin is the primary hormone which acts during the fed state and supplies the tissues with glucose. However, in fasting states, the primary hormone in action is glucagon. Glucagon helps in converting the glycogen reserves into glucose. Excess glucose, which is stored in glycogen, is converted into glucose and acts as a primary energy source.

The onset of the metabolic switch is the point of negative energy balance at which liver glycogen stores depletes, and fatty acids metabolises. However, this typically occurs beyond 12 h after the cessation of food intake. The metabolic switch from utilising glucose to fatty acid-derived ketones represents an evolutionarily trigger-shifting metabolism. From cholesterol synthesis and fat storage to the mobilisation of fat through fatty acid oxidation and fatty-acid-derived ketones while preserving muscle mass and function. Thus, intermittent fasting regimens that induce this metabolic switch can potentially improve body composition in overweight individuals.

To simplify it further:

if an individual consumes three meals a day, the metabolic switch does not get initiated, and their ketones remain low. As a result, the total utilisation of glucose is much higher than individuals on intermittent fasting eating patterns. Similarly, if a person consumes all meals within a 6-h time window, the metabolic switch activates in the next 10 hours of fasting and remains active for over 8 hours until the next meal is due. 

This metabolic switch improves metabolism and increases health span and longevity through multiple processes. First, they grow the catabolic reactions taking place in the body like autophagy which is the killing of unwanted microorganisms as well as damaged human cells. Also, this eliminates the unwanted cells and boosts the mitochondrial function for practical energy production from the food we consume, ultimately increasing overall metabolism. Intermittent fasting also prevents anabolic reactions like converting glycogen to fat, which helps lose weight while not losing muscle.

The HealthifyMe Note

Intermittent fasting improves metabolism via its effects on circadian rhythm and gastrointestinal microbiota. It also works by metabolic switching, which enhances metabolism and helps you lose weight.

Other Benefits of Intermittent Fasting

A meta-analysis indicates that intermittent fasting regimens target counteracting obesity and maximising effects on healthy living by reducing the progression of cardiovascular disease, metabolic syndrome, hypertension, and Type-2 Diabetes Mellitus. It also improves mental health. In addition, it can have anti-ageing effects.

Various hormones are involved in metabolic function, and intermittent fasting is known to alter the hormonal response and help in boosting the metabolism. 

Insulin And Glucagon

While in a fed state, insulin is the main hormone in action. Insulin helps maintain blood glucose levels and is responsible for the increase in postprandial blood glucose levels. Insulin mainly promotes anabolic reactions and helps in the storage of excess fats. However, according to data, insulin levels are reduced in fasting states, and glucagon takes over glucose metabolism. Glucagon is a hormone that gets activated after fasting states. It mobilises the fat stores and helps in increasing catabolism.


Glucocorticoids, specifically cortisol, are synthesised and secreted by the adrenal cortex. It stimulate the breakdown of macromolecules and counter-regulate insulin to maintain glucose homeostasis. Also, this helps in mobilising fat and increasing catabolism. Studies indicate that intermittent fasting increases the level and frequency of cortisol secretion.

Intermittent Fasting: Is it for Everyone?

Intermittent fasting works well for most people. However, it might not go well for specific individuals. According to research, they might experience headaches and lightheadedness. Digestive issues like constipation, diarrhoea, bloating and nausea occur too. Dehydration is also a potential complication of intermittent fasting. 

Also, some individuals may experience hypoglycemia, leading to irritability and mood changes. Few individuals have reported sleep disturbances that can lead to weight gain. However, if not done correctly, it might lead to malnutrition. It might also lead to lethargy and lack of energy. Hence it is essential to understand what works for one’s body and decide accordingly. 

Intermittent fasting does not specify the type of food to be taken but instead talks about the time at which one should have meals. However, consuming junk foods without any nutritional value will not help you boost your metabolism or help in weight loss. On the contrary, it might also lead to malnourishment and weight gain. Hence following a proper regimen and consuming nutritional meals comes hand-in-hand with intermittent fasting.

Another thing that would help you boost your metabolism is exercise. According to research, a workout is a powerful tool in boosting metabolism. In addition, combining exercise with intermittent fasting is the fastest way to increase one’s metabolism and lose weight.


Metabolic Health is an essential determinant of overall health. However, poor metabolism is becoming increasingly common in today’s world. Also, this may be due to sedentary lifestyles and changes in circadian rhythms. Poor metabolic health leads to various chronic conditions such as diabetes, hypertension, hypertriglyceridemia and hypercholesterolemia. Hence, it becomes increasingly important to maintain your metabolic health. One of the more effective ways to boost your metabolism is fasting or, more specifically, intermittent fasting.

Intermittent fasting boosts the metabolism by correcting the circadian rhythm and changing gut microbiota composition. Fasting also mobilises the fat stores and increases catabolism, leading to weight loss. In addition, intermittent fasting reduces insulin levels, which are mainly responsible for converting glucose into glycogen and fat. It also increases cortisol levels which counteract the effects of insulin. 

Intermittent fasting, however, may not work for everyone, and it is essential to understand what works for your body before jumping into this regimen. Being on junk foods for a limited period will not work and may cause weight gain. Consuming nutritious food with exercising is the best way to boost your metabolism.

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