You probably don’t need much of an explanation of what fasting is. But when it comes to how it could be good for you, well, that part might be a little less clear.
Fasting involves not taking in any calories for a specific period of time. Some religious fasting practices may require not consuming any food or beverage at all, regardless of calories.
The period might be as short as 12 hours, in the case of intermittent fasting. But traditional fasts, whether they’re for diet, cultural, or religious reasons, tend to be longer — a day or more.
If you’re assuming that giving your body an extended break from food might be helpful for weight loss, research suggests you’re right on the money. But it turns out that fasting also has a bunch of other potential health benefits. Here’s what the science has to say.
Fasting every other day has been found to be just as effective for weight loss as traditional low calorie diets. Aside from the fact that you’ll likely end up taking in fewer calories, going longer without eating seems to have a positive effect on blood sugar and fat burning. (More on that in a sec.)
And you’ll see results pretty quickly: A 2015 review concluded that whole-day fasts could help you shed up to 6 percent of your body fat in as little as 12 weeks.
However, the way you break your fast also matters. Returning to your pre-fasting ways (i.e., abandoning any lifestyle changes meant to maintain the weight loss) can result in weight regain.
As you fast, your body gradually relies more on fat than on carbs for energy, and your insulin production decreases.
Intermittent fasting can also do a bang-up job of reducing insulin resistance. That, in turn, can help make your body more sensitive to insulin, which translates into more stable blood sugar and fewer spikes and crashes.
You’ve probably heard that chronic inflammation is tied to higher risk of chronic diseases like diabetes, heart disease, and arthritis.
What you might not be aware of is that 1 month of daily 12-hour fasts could be enough to lower levels of inflammatory markers in your body. That could help keep your body in better shape as a whole.
While we’re talking about risk factors for heart disease, high cholesterol is another biggie. In a small 2010 study, fasting every other day slashed participants’ levels of LDL (“bad”) cholesterol and triglycerides by 25 and 32 percent, respectively.
In fact, long-term findings suggest that routine fasters are more than 70 percent less likely to have heart failure than folks who never fast.
Will fasting keep you from getting Alzheimer’s disease or experiencing cognitive decline? The jury’s still out, but some research on mice suggests it could have a protective effect, in part because it fights inflammation.
Some may be concerned that fasting won’t allow them to perform well in the gym or reap the full benefits of their exercise programs. But research has shown that people following intermittent fasting programs can still gain lean muscle, lose fat, and improve performance.
Fasting may have an antidepressant effect, thanks to its ability to make feel-good neurotransmitters like serotonin and endogenous opioids more available to your brain. Fasting and calorie restriction have been shown to relieve negative emotions like tension and anger and boost feelings of euphoria.
A 2008 review found that people with depression who reduced their daily calorie intake by 25 percent experienced fewer depressive symptoms over 6 months, without any apparent negative side effects.
Full disclosure: Experts still have a lot to learn about the relationship between fasting and cancer. But animal studies suggest that periodic fasting might have an anticancer effect, meaning that the practice could play a role in cancer prevention.
The research also seems to suggest that fasting could make cancer treatments like chemotherapy more effective.
Fasting seems to help cells repair themselves, which might be why it’s tied to a lower risk of many diseases. Fasting could reduce the risk of several metabolic and cardiovascular conditions — and having better overall health and less likelihood of illness could contribute to a longer life.
So, will limiting your food intake help you see 100? No guarantees, of course, but back in 1982, a study looking at rats found that rodents who fasted every other day aged at a slower rate and lived a whopping 83 percent longer than rats who didn’t fast.
Science suggests that fasting can have a number of big health benefits, including helping you lose weight, regulating your blood sugar, and keeping your body in better shape overall.
In short, there are lots of good reasons to give it a try. Just talk with your doctor first. Fasting can take different forms and can sometimes have negative side effects, so it’s worth figuring out what type of fasting plan will work best for you and how to avoid or minimize any possible downsides.
Last medically reviewed on August 12, 2020
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