As it’s usually practiced, intermittent fasting isn’t a typical diet because it doesn’t include guidelines on how much or what kinds of food you should eat. Instead, it aims to cut calories by restricting the hours when you consume food.
Many people find this easier than counting calories or cutting foods out of their diet, and it can lead to weight loss and other benefits. Studies have found it can pump up levels of human growth hormone, which reduces fat and builds muscle. Cells initiate repair processes during fasting, and insulin levels drop, making it easier for your body to use stored fat. It’s been shown to extend lifespans in animal research.
There are three primary forms of intermittent fasting with different timetables for food consumption:
- Alternate-day fasting — Eat normally one day and then fast the next either by not eating at all or having one meal of 500 or fewer calories.
- 5:2 fasting — Eat normal amounts of food five days out of the week and fast for two days.
- Daily time-restricted fasting — Eat normally during an eight-hour period every day.
Research has suggested any of these approaches, particularly alternate-day fasting, are as effective as other calorie-restricted diets for losing weight and reducing the risk of certain obesity-related conditions such as diabetes, some forms of cancer and sleep apnea.
Some studies have found intermittent fasting could be more effective for prevention of diseases related to inflammation than other types of dieting, including heart disease and high blood pressure, Alzheimer’s, arthritis and multiple sclerosis.
Hunger is the most obvious side effect of intermittent fasting, along with fatigue and irritability that could affect work performance, though most followers adjust to the change in eating pattern in about a month. You still need to follow guidelines for a healthy diet and resist the urge to binge during your eating window.
Women trying to conceive or who are pregnant or breastfeeding should avoid intermittent fasting, as well as those who have had an eating disorder. Those with diabetes, cancer, gallstones and other serious illnesses should consult a doctor first.