Fasting is an ancient tradition, having been practiced by many cultures and religions over centuries. When you fast, several things happen in your body on the cellular and molecular level. For example, your body adjusts hormone levels to make stored body fat more accessible. Your cells also initiate important repair processes and change the expression of genes. These changes are responsible for the health benefits of intermittent fasting.
Intermittent fasting, also known as intermittent energy restriction, is any of various meal timing schedules that cycle between voluntary fasting and non-fasting over a given period. Intermittent fasting may have similar effects to a calorie-restriction diet, and has been studied in the 21st century as a practice to possibly reduce the risk of diet-related diseases, such as metabolic syndrome. The American Heart Association states that intermittent fasting may produce weight loss, reduce insulin resistance, and lower the risk of cardiometabolic diseases, although its long-term sustainability is unknown. A 2019 review concluded that intermittent fasting may help with obesity, insulin resistance, dyslipidemia, hypertension, and inflammation. A 2022 review indicated that intermittent fasting is generally safe.
Methods of intermittent fasting include alternate-day fasting, periodic fasting, and daily time-restricted feeding.
- Time-restricted feeding involves eating only during 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” when the person eats less than 25% of usual energy needs, followed by a 24-hour non-fasting “feast day” period. It is the strictest form of intermittent fasting because there are more days of fasting per week.
- Periodic fasting or whole-day fasting involves any period of consecutive fasting of more than 24 hours. Such as the 5:2 diet where there are one or two fasting days per week. To the more extreme version with several days or weeks of fasting. During the fasting days, consumption of approximately 500 to 700 calories. Or about 25% of regular daily caloric intake, may be allow instead of complete fasting.
During the times when you’re not eating, water and zero-calorie beverages such as black coffee and tea are permitted. And during your eating periods, “eating normally” does not mean going crazy. You’re not likely to lose weight or get healthier if you pack your feeding times with high-calorie junk food, super-sized fried items and treats. In doing the fast correctly and ensuring that it is aligning with your mind, body and soul. You can expect a good weight loss within a month.
Keep in mind that intermittent fasting may have different effects on different people and isn’t for everyone. Some people should steer clear of trying fasting: children and teens under age 18, women who are pregnant or breastfeeding, people with diabetes or blood sugar problems and those with a history of eating disorders. Talk to your doctor if you start experiencing unusual anxiety, headaches, nausea or other symptoms after you start intermittent fasting.