Its no surprise that intermittent fasting is one of the most popular types of eating plans . You dont need to measure out food or buy any prepackaged shakes. There are no required weigh-ins or calorie counting. All you really have to do is not eat during certain hours. Its pretty simple.

There are different ways to go about it, of course. Most people do the 16:8 diet, in which you fast for 16 hours and then eat within an eight-hour window. Theres also the 5:2 diet, where you drastically cut back on calories just two days a week, and there are 24-hour fasts, where you dont eat anything one day each month.

Regardless of the method, significantly restricting when you eat can throw your body for a loop and cause a handful of odd side effects. Intermittent fasting may not be suitable for everyone. (People with a history of disordered eating, for example, should definitely avoid it .)

Its important to know what to expect before you jump into any new eating habit. Heres what happens to you mentally, physically and emotionally when youre fasting intermittently.

You might lose weight.

Many health experts, including personal trainer Jillian Michaels , say that intermittent fasting actually isnt that great for weight loss. Thats because youre not necessarily eating less or cutting back on calories. There are just longer gaps in your day when youre not eating at all.

That said, many people do lose weight because they consume fewer calories during those restricted food hours.

Eating for only eight hours a day also makes it less likely that youre having a big meal right before bedtime. Our metabolism goes down when we sleep and we burn fewer calories. Nighttime eating has been linked to both obesity and diabetes.

Intermittent fasting really does keep you from doing some really bad things, which is to eat a big meal before you go to bed, said Dr. John Morton , a bariatric surgeon with Yale Medicine. Big meals before bed are probably the worst thing you can do when it comes to weight loss, he added.

You could get super hungry.

A lot of people who fast experience hunger pangs, mainly when they start the program. Thats because our bodies are accustomed to using glucose a sugar that comes from the food we eat for fuel throughout the day. When its deprived of food (and, therefore, glucose), the body will essentially send signals saying, Hello, arent you forgetting something here?

Once your body gets into the groove of fasting, it will start burning stored body fat for energy rather than glucose. And as you spend more time in a fasted state, your body will get increasingly efficient at burning fat for energy.

In short, those hunger pangs should dissipate and your appetite will level out, Morton said. He added that fasters will ultimately have fewer cravings and hunger pangs the more consistently they fast.

In the meantime, that hungry feeling may drive some people to overeat. The natural tendency is when you havent eaten breakfast, you go, Since I didnt eat breakfast, Im going to eat more [for lunch], Morton noted.

If the hunger pains are bad enough to interfere with your daily life, get something to eat. The idea is not to starve yourself.