Fasting has been a cultural and religious tradition for centuries. More-recent trends like “intermittent fasting,” a term used to describe time-restricted eating, have focused the conversation on fasting’s impact on the body.
Intermittent fasting is often associated with dieting. But the practice has been studied for many effects unrelated to weight loss, like reduction of inflammation and cellular repair.
“Fasting activates an evolutionary program in which our body diverts nutrients normally used for growth and reproduction toward mechanisms for repair and survival,” says Whitney English, a Los Angeles–based nutritionist and founder of the practice Whitney E. RD.
- Don’t have diabetes
- Aren’t pregnant or breastfeeding
- Don’t have to take medications with food
- Don’t have a history of disordered eating
But before you begin fasting, it’s important to understand the possible benefits and drawbacks, and how they might impact your health and quality of life.
Possible Benefits of Fasting
Here’s what the research says about the possible benefits of intermittent fasting.
Lower Inflammation
Cell Repair
Improved Insulin Sensitivity
“Limiting calories also translates to reduced blood glucose, improved lipids, and reduced blood pressure,” says Amy Rothberg, MD, director of the Metabolism, Endocrinology, and Diabetes Weight Management Clinic at the University of Michigan in Ann Arbor. “This has been shown in a number of studies of low-calorie and very low-calorie diets, and time-restricted feeding has some of the same impact.”
While animal studies have shown that time-restricted feeding patterns can help to reverse the progression of metabolic diseases like diabetes in mice, findings from clinical trials done on people report mixed results. If you have diabetes, talk with your doctor before fasting.
Weight Loss, With a Catch
But there’s a catch, English says. “People do not lose more weight from fasting than they do with traditional low-calorie diets,” she says.
So why are meal plans that incorporate fasting often treated like the better way to shed pounds?
“They work simply by limiting the number of calories consumed,” Dr. Rothberg says. “Consider the average American who usually consumes meals and snacks over 12 hours every day. Limiting consumption to eight or even fewer hours generally will limit caloric intake.”
Drawbacks to Fasting
And recommendations from the Academy of Nutrition and Dietetics discourage fasting for anyone with a history of eating disorders or disordered eating, because it can make restrict-and-binge cycles worse.
The Takeaway
- Intermittent fasting is considered safe for many adults. But some adults should not try it, like pregnant people and people with a history of eating disorders.
- People on medications and those who have diabetes should talk with a doctor before starting a fasting regimen.
- Intermittent fasting may bring benefits such as weight loss, better insulin regulation, and possible reduction of inflammation.
- Still, fasting can also cause mood swings, overeating, and complications with medications.
