Humans have been fasting for thousands of years. Humans have been doing so for a variety of reasons: because there was not enough food available, out of religious reasons, and even instinctively when feeling sick.
So, there is nothing unnatural about fasting. We are well equipped to handle it, and our bodies actually tend to thrive during the periods when we do not eat. There is a long list of health benefits related to fasting, and scientists have shown time after time that fasting periods can be very beneficial for improving your overall health.
The Science Behind Fasting
Fasting, intermittent or otherwise, tends to have positive effects on your health. First, there is, of course, the obvious weight-loss effect, as we restrict calorie intake and burn fat. This is often one of the reasons why people choose to fast.
But fasting also helps the body fight various diseases and it can improve your well-being even if you are a generally healthy person. This is because when we do not eat for extended periods, the body triggers various metabolic processes which can only happen on an empty stomach.
The main trigger for these processes is the expended glucose levels in the liver that occur after about eight hours of fasting. Once the liver uses up the glucose it has stored from the food we ingest, the body starts to convert and burn up the glucose that is found in fat cells and muscles.
This is the ‘survival mode’ of the body, which shifts the processes from growth to energy conservation and maintenance. This shift has been observed to have a positive effect on mental health and it prolongs health span.
There are many types of fasting, the most common of which are:
- Water fasting, where you drink only water for a set amount of time;
- Juice fasting, where you drink only fruit or vegetable juice for a certain period;
- Partial fasting, where you eliminate certain foods or drinks from your diet for some time;
- Calorie restriction, where you restrict calories for a few days every week;
- Alternate-day fasting, where you fast every other day, but eat whatever you want during the non-fasting days. Alternatively, you can eat a maximum of 500 calories on fasting days; and
- Intermittent fasting, where you alternate between periods where you eat normally and periods where you restrict food intake partially or completely.
What Is Intermittent Fasting?
Intermittent fasting is a weight-loss approach first popularized in 2012 by Dr. Michael Mosley’s TV documentary Eat, Fast, Live Longer and his book The Fast Diet. Several other authors followed Mosley’s steps, and the trend sparked emerging research-based and anecdotal evidence on its effectiveness.
People started seeing intermittent fasting as a way to lose weight, improve their health, and simplify their lifestyles. And many studies have supported the effectiveness of this method when done properly.
The Benefits of Intermittent Fasting
Just like with other types of fasting, intermittent fasting triggers the same metabolic processes in the body which have been reported to improve overall health and longevity.
Dietitian Rachael Link lists the most common benefits of fasting that can improve your health. Looking at matters from a research-based perspective, she concludes that fasting can help with the following:
Promoting Blood Sugar Control
Fasting decreases insulin resistance, which is a state where the cells stop responding to insulin correctly and, in turn, the blood sugar levels rise. As a result of fasting, your body’s sensitivity to insulin returns to normal levels and it can collect and store glucose more efficiently.
Some studies also connect fasting to a lowered risk of diabetes. Accordingly, some health practitioners utilize fasting as a means to lower blood sugar levels among diabetic patients. However, you should note that the effects in this regard differ between men and women.
Fighting Chronic Inflammation
Researchers have found that intermittent fasting helps to lower and normalize the levels of immune cells, while also controlling proinflammatory cytokine levels. This is especially useful in the treatment of inflammatory conditions, such as multiple sclerosis.
Improving Heart Health, Blood Pressure, Triglycerides, and Cholesterol Levels
Studies have reported that after several weeks of fasting, the levels of “bad” LDL cholesterol and triglycerides decrease significantly. Studies have also observed a drop of blood pressure and even a lowered risk of coronary artery disease.
Boosting Brain Function and Preventing Neurodegenerative Disorders
According to several studies, fasting can also improve the function and structure of the brain. It can increase the generation of nerve cells that improve cognitive function and protect the brain by relieving inflammation. Although the evidence behind these claims is based on animal studies, it is nevertheless a plausible one when it comes to human health.
Helping with Weight Loss
The metabolic boost that the body receives when fasting, as well as the restricted calorie intake, have a direct effect on weight management. During fasting, the levels of the neurotransmitter norepinephrine increase. This helps the body to release the stored glucose which can be found in fat cells.
Increasing Growth Hormone Levels
The human growth hormone (HGH) plays an important role in the body. “[It’s] involved in growth, metabolism, weight loss, and muscle strength,” explains Link. During fasting, scientists have observed that this hormone’s levels increased considerably, with some cases exhibiting a five-fold increase in HGH production rate.
Delaying Aging and Extending Longevity
Due to the health processes involved in the fasting period, it is expected that fasting can keep your body younger for a longer time. Some animal studies support these expectations, reporting a delayed rate of aging and increased longevity and survival rates.
Intermittent Fasting Methods
Intermittent fasting is all about timing. It works by splitting the day or week into eating and fasting periods. When in the fasting periods, depending on the method, you eat very little or nothing at all.
There are many different variations of this type of fasting, the most popular of which are the following:
- The 16/8 method: Here you fast 16 hours of the day and eat during the remaining 8 hours. It is the simplest method to follow, and it usually means skipping breakfast and eating between noon and 8PM.
- Eat-Stop-Eat: Rather than making restrictions on a daily basis, this method involves weekly restrictions. It is a 24 hour fast where you do not eat anything, and you can repeat it once or twice a week. In this method, people usually stop eating from dinner one day until dinner the next day.
- The 5:2 Diet: This method works on restricting food intake partially. You eat normally for five days and eat only about 500-600 calories for two days.
- The 6:1 Diet: Similar to the 5:2 diet, this method involves only one day of reduced calorie intake.
When Fasting Becomes Dangerous
Despite the long list of positive effects, fasting is not recommended for every person and situation. For example, people with diabetes or low blood sugar may experience spikes and crashes in their blood sugar levels, which can be very dangerous.
In fact, even healthy people may experience blood sugar drops, especially when they begin fasting. To avoid this, ACE-certified personal trainer Iris Lami suggests taking in more calories from fats during the non-fasting periods.
Avoid fasting if you are using prescription medications, if you have low blood pressure, or if you have a history of eating disorders. Fasting is also not generally recommended for older adults, adolescents, children, people who are underweight, and women who are trying to conceive, are pregnant, or breastfeeding.
Regardless of your overall health, it is best to check if you have any underlying health conditions and consult with your doctor, especially if you are planning on fasting for more than 24 hours.
Another risk involved with fasting is improper nutrient intake. As you will be triggering your body’s ‘survival mode,’ it is important to replenish with nutrient-dense foods to maximize the potential health benefits. Go for foods rich in protein, fibers, and healthy fats. Avoid junk food and other high-carb, processed food.
Finally, you need to make sure you stay well-hydrated. Improper hydration during fasting can very easily lead to dehydration and dehydration-related problems.
The Importance of Hydration During Intermittent Fasting
Do not be surprised if you become dehydrated during intermittent fasting. This is partly because of the fact that around 20-30% of the water we get is from food, and it comes mostly from fruits and vegetables. But another major reason you may become dehydrated is due to the fact that, during fasting, your body will likely be flushing out a lot of water. This can even lead to electrolyte imbalance (which you can combat by simply adding a pinch of Himalayan salt to your water).
Some of the symptoms of dehydration during intermittent fasting may include fatigue, thirst, dry mouth, headaches, slow digestion, and bloating. So, make sure that you stay properly hydrated throughout the day. This will also help you to feel less hungry, especially when you are starting out with intermittent fasting.
Water is essential for keeping your body cells functioning. It also helps to boost the benefits of intermittent fasting. As the body enters maintenance mode, it starts to cleanse proteins and other structures that have died or become dysfunctional. Without enough water, the body cannot perform the necessary detox efficiently.
This is why you need to take special care to drink plenty of water throughout the day. Most health authorities recommend drinking around 2 liters of fluid every day. However, as Ayurvedic medicine recommends (and many health professionals suggest), we are all born unique, and this means that we all require different amounts of liquids. So, let your thirst guide you for most of the time.
The most important part of the day in relation to drinking water is the morning. Drink at least 500 ml of water after you get up to replenish the lost fluids in your body and boost your body’s metabolic rate. This effect can be enhanced when the water you drink has stronger alkaline properties.
Of course, any liquid intake can contribute to proper hydration (as they all have water), but you should be careful of what you drink during the fasting periods.
What Can You Drink During Intermittent Fasting?
Liquids are important and can be freely taken at any time of the day, regardless of whether you are in the fasting or non-fasting period. And do not worry – it is not only water that counts toward your total fluid intake. However, you should avoid drinks which may raise your glucose levels.
If you want to sweeten your drinks, stick to stevia, as it does not raise insulin and blood sugar, and it is calorie-free. However, bear in mind that it might trigger a placebo-like insulin response. If you can manage it, the best approach is to simply stay away from sweeteners during the fasting period.
Coffee can help to suppress appetite, support fat burning, and reduce insulin sensitivity over time. This makes it a great companion during intermittent fasting, as long as you do not add sugar or exceed the recommended daily dose of 400mg of caffeine.
Tea is another great addition to any fast. You can opt for green tea, black tea, oolong tea, or any other tea with antioxidant properties which can further boost the effects of your fast. Try to avoid sweetening it, however.
Apple Cider Vinegar
If you are using apple cider vinegar for its health benefits, there is no reason to stop during fasting. Its potent biological effects, and its ability to lower blood sugar levels, fight cholesterol, and help with weight loss can only add to the effectiveness of the fast.
Fats like coconut oil, butter, or even fats from almond milk will not affect your fasting period negatively as long as you keep your calorie intake below 50 calories. Even if you exceed 50 calories, the body should not switch off too many of its current fast-induced processes, but it will likely stop the detox process.
Copper-infused water can also be a great companion during intermittent fasting. Copper-infused water can supply your body with natural alkaline water, which can help your body thrive. Simply fill up your copper water bottle and leave it overnight. Then, enjoy its benefits with the first sip in the morning.
Intermittent fasting is one of the most popular fasting methods as it allows more flexibility in how you will arrange your fasting and non-fasting periods. However, avoid eating before going to bed and make sure you stay properly hydrated.
About the Authors: This article was collaboratively written by our team of researchers and writers with the benefit of all available scientific studies and other relevant literature. Our team of researchers and writers include experienced health researchers including a qualified medical professional. Please note that information in this article is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment.