Fasting is voluntary abstinence or reduction of some or all foods, beverages or both, for a period of time. Although it is sometimes seen as harmful to health, short-term fasting, and done responsibly, can offer health benefits.
Essentially, fasting cleanses our body of toxins and forces cells to processes that are generally not stimulated when a steady flow of fuel from food is always present.
When fasting, the body does not have its usual access to glucose, forcing cells to resort to other means and materials to produce energy. As a result, the body begins gluconeogenesis, a natural process of producing its own sugar.
The liver helps to convert non-carbohydrate, such as lactate, amino acids, and fats, into glucose energy. As our bodies conserve energy during fasting, our basal metabolic rate (the amount of energy our bodies burn during rest) becomes more efficient, thereby lowering heart rate and blood pressure. In fact, a 2021 study also showed that fasting reduces pressure by remodeling the intestinal microbiota.
The types of fasting
In laboratory studies, these three types of caloric restriction, or fasting, have shown positive effects on longevity:
Power with restricted time
This is the process of limiting calorie intake to a specific period of time that aligns with our circadian rhythm. Circadian rhythm is often referred to as our biological clock, the natural cycle that tells our body when to sleep, wake up, eat, and more.
Eating only for a period of eight hours to twelve hours every day is an example of alignment with our circadian rhythm. Body systems work best when synchronized with each other.
Therefore, evening snacks, when our body usually sleeps, leave our natural repair system out of sync. In addition, giving our body more time to repair itself is beneficial to our health.
Periodic fasting with diets that mimic fasting
This means limiting calorie intake for three to five days, causing cells to debut glycogen stocks and start ketosis. Although this can be done without eating food, it is not considered the safest option.
A specific diet limited to five-day calories (about 1,000 calories per day) is enough to mimic fasting without depleting nutrients. It is speculated that this method is superior to two-day fasting, allowing the body to enter ketosis and start a true cleansing.
Intermittent fasting is a dietary pattern that alternates periods of fasting and feeding. It does not specify what foods you should eat, but when to eat them.
Common methods of intermittent fasting involve daily fasting of 16 hours of fasting for 24 hours, twice a week.
8 health benefits of fasting, supported by science
1. Promotes blood sugar control by reducing insulin resistance
Several studies have found that fasting can improve blood sugar control, which can be especially useful for people at risk of diabetes.
A study of 10 people with type 2 diabetes showed that short-term intermittent fasting significantly decreased blood sugar levels. Meanwhile, a review found that both intermittent fasting and alternate-day fasting were as effective as limiting calorie intake in reducing insulin resistance.
Decreased insulin resistance can increase your body’s sensitivity to insulin, allowing it to transport glucose from the bloodstream to cells more efficiently.
2. Fights inflammation
Although acute inflammation is a normal immune process used to help fight infections, chronic inflammation can have serious health consequences.
Research reveals that inflammation may be involved in the development of chronic conditions such as heart disease, cancer, and rheumatoid arthritis.
However, some studies have found that fasting can help lower levels of inflammation and help promote better health.
For example, a study with 50 healthy adults ?? showed that intermittent one-month fasting significantly decreased levels of inflammatory markers. Another small study found the same effect when people fasted 12 hours a day for a month.
3. Can improve heart health
Heart disease is the leading global cause of death, accounting for about 31.5% of deaths worldwide.
Changing your diet and lifestyle is one of the most effective ways to reduce the risk of heart disease. Some research has found that incorporating fasting into your routine can be especially beneficial when it comes to heart health.
A small study revealed that eight weeks of fasting every other day reduced levels of bad LDL cholesterol and triglycerides in the blood by 25% and 32%, respectively.
In addition, a larger study of 4,629 people associated fasting with a lower risk of coronary artery disease, as well as a significantly lower risk of diabetes, which is an important risk factor for heart disease.
4. Can boost brain function and prevent neurodegenerative diseases
A study in rats showed that intermittent fasting for 11 months was able to improve the function and structure of the brain of these animals.
Other studies, also conducted on animals, have reported that fasting can protect brain health and increase nerve cell generation to help improve cognitive function.
As it helps relieve inflammation, fasting can also help in the prevention of neurodegenerative diseases.
In particular, animal studies suggest that fasting can protect against and improve outcomes for conditions such as Alzheimer’s and Parkinson’s disease. However, more targeted studies are needed to evaluate the effects of fasting on brain function in humans.
5. Contributes to weight loss
Many people who diet start fasting looking for a quick and easy way to lose a few pounds.
Theoretically, abstaining from all or certain foods and beverages should decrease overall calorie intake, which can lead to increased weight loss over time.
Some research has also found that short-term fasting can boost metabolism by increasing levels of the neurotransmitter norepinephrine, which can increase weight loss.
In fact, a review showed that fasting a full day can reduce body weight by up to 9% and significantly decrease body fat over 1224 weeks.
Another review found that intermittent fasting for 312 weeks was as effective at inducing weight loss as continuous caloric restriction and decreased body weight and fat mass by up to 8% and 16%, respectively.
In addition, the same review found that fasting is more effective than caloric restriction in increasing fat loss and, at the same time, in preserving muscle tissue.
6. Can delay aging and prolong longevity
Several animal studies have found promising results on the potential effects of fasting on the prolongation of life.
In one of them, rats that fasted every two days experienced a delayed aging rate and lived 83% longer than mice that did not fast. Other animal experiments have obtained similar results, reporting that fasting may be effective in increasing longevity and survival rates.
However, the available research still focuses on the effects of the practice on animals. Therefore, more studies are needed to understand how fasting can affect longevity and aging in humans.
7. Can help in cancer prevention and increase the effectiveness of chemotherapy
Animal and test-tube studies indicate that fasting can benefit cancer treatment and prevention.
In fact, a study with rats found that fasting every other day helped block the formation of tumors. In the same vein, a test-tube study showed that cancer cell exposure to multiple fasting cycles was as effective as chemotherapy to slow tumor growth and increase the effectiveness of chemotherapy drugs in cancer formation.
Despite these promising findings, further studies are needed to verify how fasting can influence the development and treatment of cancer in humans.
8. Stimulates and accelerates the production of growth hormone
One study showed that HGH, a growth hormone, is stimulated by fasting. Although it is related to height gain, HGH is also responsible for fat burning. That’s because it transports the stored fat into the bloodstream to be used as energy.
In addition, HGH is associated with the protection of lean muscle mass and metabolic balance. All these processes are accelerated when we fast, according to the study conducted with more than 200 people. In it, it was observed that HGH, during a 24-hour period of fasting, increased on average by 1,300% in women, and almost 2,000% in men.
Safety and side effects
Hunger is the main side effect of intermittent fasting. You may also feel weak and your brain may not function as well as you are used to.
These effects can be temporary as it may take some time for your body to adapt to the new meal schedule. It is advisable to seek medical and nutritional and, if necessary, psychological guidance before starting any fasting method, to prevent the development of eating disorders, possible episodes of compulsion, and symptoms such as weakness, dizziness, and fatigue.
In addition, an area professional will help you properly assemble your food plan and determine the hours or days of fasting properly. Medical follow-up is indicated especially if you:
- You have diabetes
- You have low blood pressure
- Take medicines
- It is underweight
- You have a history of eating disorders
- You’re trying to get pregnant.
- Has a history of amenorrhea
- Are you pregnant or breastfeeding
- Have problems with regulating blood sugar