5 Surprising Health Benefits of Fasting
Fasting is a natural process of not eating or drinking any calorie-containing foods and whether you know it or not, you fast every single day. Hint: You did it last night while sleeping.
For thousands of years, people have voluntarily fasted for health and spiritual reasons. While you may understand the benefits of eating a nutritious diet, you might be surprised to learn that not eating can result in some unique benefits, too.
What Are the Potential Health Benefits of Fasting?
When it comes to fasting, most people have probably heard about the potential for weight loss but did you know there are other associated benefits?
1. Support weight management
Fasting can be a useful tool for supporting weight management. But it’s not necessarily better than plain old calorie restriction where you cut a small, but set amount of calories, each day.
A 2015 review looked at 40 studies and concluded that fasting isn’t superior to calorie restriction. Both methods led to comparable results. One criticism of the review is that it lumped together different types of intermittent fasts, and not all fasts are created equal. Fasting plans may require you to skip or skimp on food anywhere between eight to 24 hours and beyond.
Both methods will reduce the total number of calories you take in and result in similar benefits. According to Samantha Thoms, MPH, RD and owner of Budget Dietitian, “Fasting or calorie restriction won’t produce miracle results. Both should be seen as a lifestyle change. You need to decide which is more sustainable in the long-term, and talking to a dietitian or nutrition expert can help.”
If you do decide to give fasting a try, Thoms recommends shorter fasts, for example, an eight to 12-hour overnight fast, that can give you similar benefits and is more sustainable over time.
2. Potentially retain muscle mass while cutting calories
When you’re in a calorie deficit, your body looks to other sources for energy, which means your muscles can start to break down in order to feed your body. This isn’t an ideal scenario because your muscles help keep your resting metabolic rate from decreasing.
A 2011 review suggests that fasting, particularly every other day, can help you preserve more lean muscle mass than classic calorie cutting. Still, the evidence is sparse and mixed so the jury is still out on that one and more research needs to be done.
3. May help promote healthy brain function
Fasting may help support healthy brain function and mental clarity, but we’re lacking enough quality human trials to confirm it. What we do have is animal research to suggest there might be something to it.
Mouse-model research shows that fasting supports cognitive function and structure. The National Institute on Aging notes that during a fast, the brain switches its main fuel source from glucose to ketones, which can help brain cells work at full capacity. And, some scientists believe that because ketones are a more efficient energy source compared to glucose, they may help protect against aging-related decline in the central nervous system.
4. Support heart health in the long run
Fasting may promote cardiovascular health. This 2018 review found that most intermittent fasting regimens supported healthy cholesterol and triglyceride levels, as well as blood pressure. But these benefits are not unique to fasting. These results can also be seen with classic calorie restriction.
5. Promote healthy aging
Fasting can mean calorie restriction and there is literature showing that eating less can support healthy aging. But the science isn’t black and white and the majority of the research that has been done has been on animals.
The body of work conducted on humans is promising but more research is needed before we can appreciate its long-term effects. And to date, there are no data on calorie restriction and longevity in humans.
How Long Should You Fast For?
Even if the benefits intrigue you, do note that fasting isn’t for everyone, especially pregnant or breastfeeding women, those prone to eating disorders, growing children, or people with diabetes, pre-diabetes, or some other chronic conditions.
Thoms advises, “If you decide to try fasting, ease into it. Pay attention to your body and give it two to three weeks. If fasting isn’t right for you, move on. You can always reach similar benefits with a shorter fast. Also, don’t underestimate the power of a nutritious diet, regular exercise and adequate sleep.”
That said, there’s no set guideline for how long you should fast. Going without food for eight to 12 hours seems a safe bet for most healthy adults. For longer fasts, please consult a medical professional to see if it’s right for you.