For centuries, people have fasted to cleanse their bodies and strengthen their souls. Now, celebrities, athletes and everyday folks say the ancient practice is adding new zest to their lives.
These modern-day fasters insist that severely restricting food intake for a period of time – often on one or two days a week – has boosted their bodies and fired up creativity. Proponents of fasting reportedly include:
- Singers Beyonce and Jennifer Lopez
- Actresses Liv Tyler and Jennifer Aniston
- Fashion model Miranda Kerr
- Rock singer Chris Martin of Coldplay
Science agrees that fasting may indeed offer health benefits, says Courtney Peterson, an assistant professor at Louisiana State University's Pennington Biomedical Research Center.
"Fasting is largely beneficial," she says.
For example, a study published in 2015 and partially funded by the National Institutes of Health found that mice placed on a restricted-calorie diet had:
- Lower blood glucose and insulin levels
- Less fat around their organs
- Greater bone density at old age
- Increased nerve cell development in the brain
- Fewer tumors and skin lesions at the end of life
However, there are various types of fasting, and you need to know the distinctions if you are going to fast safely and effectively, Peterson says.
The types of fasting
Many people think of fasting as going a day or two without eating food while subsisting solely on water. But it can be difficult to fast so strictly, Peterson says.
Instead, you may find it easier to benefit from intermittent fasting – alternating periods of fasting with periods of eating.
Intermittent fasting comes in several different forms. Many celebrities who fast use what is known as a "5:2 diet" over the course of a week. In this diet, you severely restrict calorie intake on two days, but eat normally on the other five days.
Other people employ a daily intermittent fasting diet. One example of this approach is to divide up the day into two periods: A fast of 16 hours, followed by an eight-hour window in which all eating takes place.
Peterson says research in rodents indicates that intermittent fasting promotes weight loss without depleting muscle. She currently is involved in studies to see if such benefits are replicated in humans who fast intermittently.
Last year's NIH study tested a very small group of people to see how their bodies reacted to calorie restriction. Participants had improved blood glucose levels and decreased body weight compared to a control group.
Should you do it?
While fasting is beneficial for many people, it is not right for everybody, Peterson says.
"We don't want pregnant women or children do be doing any of this type of fasting," she says.
That is because both pregnant women and children are in "growth mode." While feeding helps the body to grow, fasting is more aligned with body "repair," Peterson says.
If you want to try fasting, it may be wise to consult with a health professional first. Done carelessly or incorrectly, fasting can deplete electrolytes in the body and cause other health issues, Peterson says.
To learn more about the benefits of intermittent fasting, Peterson recommends two books: "The Every Other Day Diet" by Krista Varady and "The Fast Diet" by Michael Mosley.
If fasting sounds too extreme, Peterson suggests a modified approach. For example, you could try eating bigger meals earlier in the day. "By frontloading more calories earlier in the day, you may get an extra benefit," Peterson says.
She cites a 2013 study published in the journal Obesity that found that women who ate a 700-calorie breakfast, 500-calorie lunch and 200-calorie dinner lost 2.5 times as much weight over a 12-week period as women who consumed that diet in reverse -- a 200-calorie breakfast, 500-calorie lunch and 700-calorie dinner.
Research also appears to have shattered one other dietary myth: The number of meals you eat in a day has little bearing on how much weight you lose. So, three square meals a day is just as good as six smaller meal, Peterson says.
