Fasting, an age-old practice deeply rooted in our history and traditions, has been gaining more attention lately for its potential to boost our metabolic health in the present day. Metabolic health is all about how our bodies handle energy, and it plays a fundamental role in our overall health. In this article, we'll explore the scientific and practical aspects of fasting and how it can benefit our metabolic health. From making our bodies more sensitive to insulin to helping with weight management and heart health, fasting is becoming an intriguing topic in the medical community. Our aim is to provide useful insights and advice, both for healthcare providers and the general public, so they can understand the potential advantages of fasting in optimizing their metabolic health.
Fasting can be a valuable strategy for enhancing metabolic health, as it offers benefits such as improved insulin sensitivity, weight management, and reduced inflammation.
Boosts Metabolism
Modern diets are high in calories and our meal patterns are out of sync with the body’s natural circadian rhythm. High calorie consumption over a long period of time causes metabolic damage that leads to obesity, diabetes, heart disease, stroke and dementia. Adopting a fasting practice aligned with your circadian rhythm helps to boost metabolism, reduce risk factors and prevent chronic diseases.
During fasting, your body switches from relying on glucose for energy to utilizing fat for fuel. This is because your glucose stores are depleted and the lipids in your fat cells are released to be used as fuel. Your liver also metabolizes these fatty acids into ketones that are used to power your cells and organs. Using fat for energy instead of glucose helps to preserve muscle mass and promotes optimal metabolic health.
In addition, during prolonged periods of fasting, your body releases human growth hormone. This hormone improves satiety and promotes fat burning. It also stimulates protein synthesis and enhances mitochondrial function. Fasting can also trigger elevated levels of norepinephrine, which is a neurotransmitter that increases fat burning and preserves muscle mass.
A new study examined the effects of early time-restricted feeding (ETRF), which is a type of intermittent fasting that restricts calories to the first eight hours of each day. This was the first study to assess the impact of ETRF on glycemic control, independent of weight loss.
The researchers found that eating ETRF improved cardiometabolic markers compared to a standard high-protein diet. In addition, it triggered ketone elevation and autophagy, a process that helps to eliminate damaged proteins and organelles and protects against age-related declines in brain function. The authors concluded that a combination of ETRF with a high-quality, whole foods diet can optimize metabolic health.
Increases Energy Levels
Your body uses two primary fuel sources for energy: glucose, which comes from carbohydrates you eat and sugar in your bloodstream, and fat, which can be converted to fuel in the form of ketones. After a typical meal, your blood glucose levels rise and trigger the release of insulin, which tells cells to take up the extra glucose for energy. Any remaining glucose gets stored in the liver and muscles as glycogen or converted to fat. Fasting reduces insulin levels and shifts your body’s metabolism to fat-burning, resulting in the production of ketone bodies, which serve as an excellent fuel source and help maintain metabolic flexibility.
In addition to boosting lipid metabolism, a prolonged fast can increase your levels of human growth hormone and norepinephrine. These hormones promote muscle growth and improve alertness and concentration, while also promoting fat loss.
As a result, intermittent fasting may provide more sustained energy than daily calorie restriction diets. Unlike many low-calorie diets, which cause both muscle and fat loss, intermittent fasting has been shown to preserve muscle mass and increase fat loss while improving health-related biomarkers such as ghrelin levels (the “hunger” hormone).
However, it is important to note that when you do eat during your eating window, be sure to eat high-quality, nutrient-dense whole foods. Choose lean proteins, healthy fats such as nuts and seeds, and vegetable-based carbs such as sweet potato, yam, and taro. If you plan on practicing long-term intermittent fasting, it is advisable to consult your physician or healthcare professional. This is particularly true if you have hormonal imbalances or have a history of eating disorders. In addition, you should always hydrate during periods of fasting to prevent dehydration.
Improves Insulin Sensitivity
One of the fantastic perks of fasting for better metabolic health is its ability to make our bodies more responsive to insulin. Insulin is a vital hormone created by our pancreas. It's in charge of managing the sugar levels in our blood and helping our cells take in glucose for energy. Keeping our sensitivity to insulin in check is crucial, as a drop in sensitivity can lead to a condition called insulin resistance, which is linked to type 2 diabetes and other metabolic issues.
Fasting, especially intermittent fasting, is proven to make a big difference in insulin sensitivity. When we give our bodies a break from food for longer periods, like during overnight fasts or extended intermittent fasting, our bodies use up stored glycogen and start using fat for energy. This process causes our cells to respond more efficiently to insulin.
What's more, fasting also tones down the sharp spikes in blood sugar that typically happen after we eat. By managing these spikes, fasting reduces the need for our bodies to pump out too much insulin. This, in turn, helps cut the stress on our pancreas. As a result, fasting can be a way to stop or manage type 2 diabetes and help keep our blood sugar stable.
Better sensitivity to insulin isn't just good for metabolic health – it also helps protect us from other health problems like heart disease and obesity. This shows that fasting can be a potent tool in taking care of metabolic issues, which is a big win for our overall health.
Reduces Inflammation
Inflammation is an important part of the metabolic process, but when it becomes out of control, it can cause insulin resistance. The good news is that intermittent fasting can reduce inflammation by training your body to be more metabolically flexible. Fasting can also boost human growth hormone, which encourages fat burn and protects lean muscle.
In addition to helping your body burn fat, fasting can also help you get rid of bad bacteria. This can help lower your risk of heart disease, diabetes, and other diseases. In fact, a 2021 study in Advances in Nutrition found that people who practiced time-restricted eating were significantly less likely to develop inflammatory conditions like cardiovascular disease and cancer.
When you’re doing an intermittent fast, it’s best to eat high-quality, nutrient-dense foods during your eating window. This will ensure that you’re getting all the benefits of the diet. Make sure you include plenty of veggies, fruits, and lean proteins. This will help you maintain your metabolic health and prevent weight loss plateaus.
It’s also important to drink plenty of water and other fluids, especially when you’re doing a short-term fast. This will prevent dehydration and supply your body with the nutrients it needs.
Decreases Age-Related Diseases
With a high-protein, low-sugar diet and regular exercise, fasting can help you maintain metabolic health. In fact, studies have shown that this type of diet reduces the risk of obesity, diabetes, cardiovascular disease, stroke and dementia by increasing satiety, decreasing over-consumption and promoting a healthy body composition.
Modern people tend to consume three or more meals daily with long daily energy intake periods and short, non-consecutive fasting periods. As a result, their cells are constantly flooded with glucose. When glucose concentrations in the blood rise after a meal, the body releases insulin, which tells cells to use the extra glucose as fuel or store it as glycogen or fat.
In contrast, the body’s response to prolonged fasting is much different. This is because when carbohydrates are no longer available, the body turns to other sources of energy. It derives glucose from noncarbohydrate sources, including amino acids, through a process called gluconeogenesis. The result is a reduction in insulin resistance, improved glycemic control and the triggering of ketone elevations.
Prolonged fasting also increases the concentrations of norepinephrine and epinephrine, which increase alertness and improve mood. It also increases growth hormone and reduces the breakdown of muscle protein. Finally, increased ketone levels and decreased insulin levels also help reduce inflammation.
Weight Management
One more significant advantage of fasting for your metabolic health is how it can help you with weight management. These days, many people struggle with weight, and finding effective ways to control it is crucial. Fasting offers various methods, such as intermittent fasting and time-restricted feeding, that can be really helpful for those who want to reach and maintain a healthy weight.
Intermittent fasting involves alternating between eating and fasting periods, and it has proven to be effective for weight loss. By limiting the time during which you eat, you naturally consume fewer calories, which creates a calorie deficit that leads to shedding those extra pounds. Additionally, fasting encourages your body to use stored fat for energy, which aids in reducing body fat.
Time-restricted feeding is another approach. It sets a specific window for eating each day, usually around 8-12 hours. This method can help control your appetite better and reduce your overall calorie intake, making it easier to manage your weight.
Fasting also triggers changes in your hormones that affect your appetite and metabolism. It can lower the levels of ghrelin, the hormone responsible for making you hungry, and increase the levels of hormones like peptide YY (PYY) and leptin, which make you feel full. These hormonal shifts support long-term weight management by preventing overeating.
Incorporating fasting into a comprehensive weight management plan, along with a balanced diet and regular physical activity, can be a valuable strategy for those looking to achieve and maintain a healthy weight. However, remember to be cautious and consult with healthcare professionals to ensure fasting is safe and effective for your individual needs.
Boosts Brain Health
Studies show that intermittent fasting promotes brain health and can help to ward off neurodegenerative diseases like Alzheimer's, Parkinson's, and dementia. It does so by increasing BDNF levels, optimizing neuroplasticity and improving the resistance of the brain to stress. Additionally, IF improves metabolic functions that enhance learning, memory and response to stress, such as those of glucose, glutamate, and cytochrome.
During periods of fasting, the body depletes its glycogen stores and triggers fat cells to release fatty acids that are then converted into ketones, which are used as energy by the cells, including neurons. This is known as the Glucose to Ketone Switch, and it occurs in people who do not consume food for extended periods of time, such as those who practice intermittent fasting.
In a series of experiments, scientists have discovered that the fatty acids produced during periods of fasting stimulate the growth of new brain cells and promote the removal of damaged cells. The cellular cleanup process also known as autophagy helps to eliminate toxic proteins that can lead to the formation of tangles in the brain, a common characteristic of Alzheimer's disease and other types of dementia.
Researchers found that those who regularly practiced intermittent fasting experienced less cognitive decline over time than people who followed a free-eating diet. This is because those who fasted regularly increased their levels of BDNF, which stimulates the growth of new neurons in the brain. Additionally, those who regularly fasted had higher levels of butyrate, a metabolite of the good bacteria in their gut that stimulates BDNF production. In addition, those who regularly fasted had lower levels of inflammation, which can lead to a number of different disorders, including heart disease, diabetes, and multiple sclerosis.
The Bottom Line
Changing your eating habits to include intermittent fasting can lead to weight loss and improved metabolic health. This is because it helps to teach the body to be more metabolically flexible. In other words, it may help improve insulin sensitivity and reduce insulin resistance.
The two primary fuel sources for cells are glucose (delivered to the cell through the carbohydrates you eat) and fat. Glucose is used immediately, while fat is stored for future energy. After a typical meal, blood sugar levels peak, and then start to decline. Your body also releases insulin after a meal, and this tells the cells to take up glucose for energy. Any unused glucose will be stored in the liver and muscles as glycogen or converted to fat.
A recent study in the journal Cell Metabolism found that those who restricted their eating to 10 hours a day over a three-month period saw significant weight loss and improvements in multiple risk factors for heart disease, including excess belly fat and high cholesterol. The study included individuals with metabolic syndrome, which is a group of conditions including mild class one obesity and other cardiovascular risks like high blood pressure.
It is important to speak with your doctor before starting an intermittent fasting routine, especially if you are on insulin or other medications that require monitoring. In addition, it is important to be aware of how consuming carbohydrates, such as fruit, affects your blood sugar level. You should consume foods with a low glycemic index such as vegetables, fruits, whole wheat bread and roti, paneer, makhana etc. It is also important to drink plenty of fluids during a fast, such as water, green tea and lemonade (without sugar), to avoid dehydration.
