There are some benefits to intermittent fasting.
Types of Fasting
People have fasted for religious, political, health, and dietary reasons. The act of fasting is a willing act of reducing or abstaining from some or all types of food and drink for a time. If a person avoids all liquid and food, it is called an “absolute fast”. Fasts may also just limit certain types of food or be engaged in intermittently. Some people, historically, have fasted for political purposes while others have engaged in fasting for religious reasons, such as in the Bahá’í Faith, Buddhism, Christianity, Hinduism, Islam, Jainism, Judaism, Sikhism, and Taoism.1 Recently, intermittent fasting has become a popular trend in dieting. One of these is called the 5:2 Fast Diet, in which participants eat a recommended caloric intake for 5 days and then reduce their intake to only 25% for 2 days (600 calories for men and 500 calories for women, per day). The author of these diet books, Dr. Michael Mosley, says that this type of fasting diet can improve insulin sensitivity, cholesterol, and blood pressure. A recent study has shown that “1 day of water-only fasting a week” may be able to “reduce the risk of diabetes” in high-risk individuals. Another study found that fasting for two to four days may “reboot the immune system”. In fact, this may help protect people from the cell damage of chemotherapy and aging.2
Health Benefits and Concerns
Fasting can help with weight loss by allowing the body to use fat as energy. It can speed up the metabolism and lengthen the life span. People can learn what hunger feels like from fasting, allowing the correct hormones to be released to signal when it is time to stop eating. Fasting can also improve eating patterns. BDNF production is boosted by fasting, and that brain-derived neurotrophic factor is a protein that protects against Parkinson’s and Alzheimer’s diseases. BDNF helps to promote neural health. In addition to improving insulin sensitivity and the immune system, fasting can prevent acne and clear the skin. It also “contributes to self-enlightenment”.3 Fasting has its downsides, especially if it is not planned well. In terms of weight loss, it can lead to quick fluid loss that does not last, meaning that the weight loss may reverse as the metabolism slows. Those who choose to fast, but who have not had a healthy diet prior to the fast, could end up in a dangerous situation. This is especially true for people who are on medication, who have a compromised immune system, or who have kidney and liver damage. People with malnutrition, cardiac arrhythmias, renal problems, or pregnancy should not fast, according to Dr. Joel Fuhrman.4 Those with eating disorders, children, those recovering from surgery, and people with Type 1 diabetes shouldn’t engage in fasting. For people who choose to fast, it is safest to consult a healthcare provider, first. According to Dr. Valter Longo, there is a fasting-mimicking diet (FMD) option that has been studied that may be beneficial. It is a diet “low in protein, low in unhealthy fats and high in healthy fats” that leads to “low glucose levels and high levels of ketone bodies” to mimic fasting. One study of this diet showed that it “triggered immune cell regeneration and extended the lifespan of mice”.5