Intermittent fasting is an eating pattern where you cycle between periods of eating and fasting. Numerous studies show that it can have powerful benefits for your body and brain.
Intermittent fasting (IF) is a term for an eating pattern that cycles between periods of fasting and eating. It does not say anything about which foods you should eat, but rather when you should eat them. In this respect, it is not a “diet” in the conventional sense. It is more accurately described as an “eating pattern.” Common intermittent fasting methods involve daily 16 hour fasts, or fasting for 24 hours, twice per week.
Humans have actually been fasting throughout evolution. Sometimes it was done because food was not available, and it has also been a part of major religions, including Islam, Christianity and Buddhism.
Here are evidence-based health benefits of intermittent fasting:
1. One of intermittent fasting’s main effects seems to be increasing the body’s responsiveness to insulin, the hormone that regulates blood sugar. Decreased sensitivity to insulin often accompanies obesity and has been linked to diabetes and heart failure; long-lived animals and people tend to have unusually low insulin, presumably because their cells are more sensitive to the hormone and therefore need less of it. A recent study at the Salk Institute for Biological Studies in La Jolla, Calif., showed that mice that feasted on fatty foods for eight hours a day and subsequently fasted for the rest of each day did not become obese or show dangerously high insulin levels.
2. Intermittent fasting helps you eat fewer calories, while boosting metabolism.
3. Studies show that intermittent fasting can reduce oxidative damage and inflammation in the body. This should have benefits against aging and development of numerous diseases.
4. Intermittent fasting has been shown to help prevent cancer in animal studies.
5. Intermittent fasting may have important benefits for brain health. It may increase growth of new neurons and protect the brain from damage.
Intermittent fasting acts in part as a form of mild stress that continually revs up cellular defenses against molecular damage. For instance, occasional fasting increases the levels of “chaperone proteins,” which prevent the incorrect assembly of other molecules in the cell. Additionally, fasting mice have higher levels of brain-derived neurotrophic factor (BDNF), a protein that prevents stressed neurons from dying. Low levels of BDNF have been linked to everything from depression to Alzheimer’s, although it is still unclear whether these findings reflect cause and effect. Fasting also ramps up autophagy, a kind of garbage-disposal system in cells that gets rid of damaged molecules, including ones that have been previously tied to Alzheimer’s, Parkinson’s and other neurological diseases.
The idea that periodic fasting may offer some of the same health benefits as continuous calorie restriction—and allows for some feasting while slimming down—has convinced an increasing number of people to try it, says Steve Mount, a University of Maryland genetics professor who has moderated a Yahoo discussion group on intermittent fasting for more than seven years. Intermittent fasting “isn’t a panacea—it’s always hard to lose weight,” adds Mount, who has fasted three days a week since 2004. “But the theory [that it activates the same signaling pathways in cells as calorie restriction] makes sense.”