But intermittent fasting isnt for everyone. After all, it involves fasting (yup, going without food) for a set period of time. Clearly, thats not going to feel good for everyone.

While you probably get the gist of fasting, you might be a little fuzzy on the details of what it means to be on an intermittent no-eating plan. Heres how it works, plus what you can actually eat when youre on it.

Intermittent fasting centers around a pattern of eating and fasting periods, that is, times when you dont eat. Intermittent fasting is when you allow yourself to eat only during a specified window of time each day, explains Alissa Rumsey, RD, a NYC-based dietitian and owner of Alissa Rumsey Nutrition and Wellness . It usually involves fasting for a certain number of hours or even days that are spaced out during the week, and theres no right way to do this, says Sonya Angelone, RD, a spokeswoman for the Academy of Nutrition and Dietetics.

There are so many different kinds of fasting now, Rumsey says. The 5:2 diet is one. On this diet, women eat less than 500 calories (for men, it's less than 600) for two non-consecutive days a week. So, you might have a 500 calorie day on Tuesday and Thursday, and then eat normally on Monday, Wednesday, Friday, Saturday, and Sunday. With the 5:2 diet, you dont need to eat certain foodsyou just limit how much you eat during certain periods of time.

Another popular type of intermittent fasting is the 16:8 diet . With this diet, you only eat during eight hours of the day. You can technically choose when you want your eight-hour period to be, but most people tend to stop eating at a certain time in the evening, like 6 p.m., and then wait to eat again until 16 hours later (in this case, it would be at 10 a.m.). That way, youre sleeping for part of your fast instead of sitting around, thinking about the food youre not eating for a good part of the day.

Theres also something known as the 24-hour fast (or Complete Alternate Day Fasting). That requires fasting from all food for 24 hours once or twice per week, Angelone explains.

BTW: Youre not expected to survive on just air during fasting periods. People usually will have water, tea, coffee, and other very low calorie or non-caloric drinks during this time.

Back in 2012, BBC journalist Michael Mosley released a TV documentary called Eat Fast, Live Longer, followed by a book, The Fast Diet , which brought the idea of intermittent fasting to the cultural forefront. In 2013, journalist Kate Harrison published her book The 5:2 Diet and in 2016, Jason Fung, MD, had a bestseller with The Obesity Code , a book that spelled out how to use intermittent fasting to combat insulin resistance and reach a healthy weight.

Along with the books came celebrity endorsements of the diet, and that certainly hasn't hurt the intermittent fasting trend, either. (I mean, have you seen Halle Berry?) Many influential people have talked about their experience with intermittent fasting so it has gotten quite a bit of spotlight and exposure on social media platforms, Rumsey says.

People also like intermittent fasting because it doesnt take a lot of thought. It doesnt require counting calories, macros, or measuring ketones, Angelone points out. You can eat most anything you want between a specific window of time, although most programs recommend eating healthfully when you do eat.

Research has found a link between intermittent fasting and weight loss, but there isn't much research to prove that intermittent fasting is a better weight loss method than other diets. For example: a meta-analysis published in the JBI Database of Systematic Reviews and Implementation Reports in 2018 found that intermittent fasting had similar weight loss results to a traditional calorie-restricted diet.

In some cases, even when intermittent fasting did lead to weight loss, it wasn't the most sustainable diet. One randomized clinical trial of 100 metabolically healthy, obese adults (published in JAMA Internal Medicine in 2017) found that those who fasted every other day for a year had only slightly more weight loss than those who ate a restricted-calorie diet on a daily basis. The difference in weight loss was so slight that it wasnt considered clinically significant, and 38 percent of people in the alternate-day fasting group had trouble sticking with the diet. Whomp whomp.

Basically, research has found that you can lose weight on an intermittent fasting diet, but you can also lose weight by watching what you eat. Its also worth pointing out that weight loss due to intermittent fasting isnt guaranteed to last. Some people may experience weight loss in the short-term, but many people eventually gain that weight back, Rumsey says.

And, most intermittent fasting research has only been done on people who are obese. There is almost no credible research that shows intermittent fasting is good for people at a healthy weight, says Scott Keatley , RD, of Keatley Medical Nutrition Therapy. If you're curious about intermittent fasting but don't have much weight to lose, it might not be the best diet for you.

There is a growing body of research that suggests that intermittent fasting does have health benefits outside of weight loss. One study published in Cell Metabolism in 2018 linked intermittent fasting and lower insulin levels and blood pressure. Researchers followed a small group of obese men with prediabetessome were put on a 16:8 intermittent fasting diet, while others ate over a period of 12 hours. Both groups didnt gain or lose weight. But after five weeks, the men in the 16:8 group had much lower insulin levels and improved insulin sensitivity. They also significantly lowered their blood pressure and said they had decreased appetites. They werent as hungry as they were beforeeven though they were fasting.

It might seem counterintuitive, but appetite control is a big benefit of fasting. A recent study in the journal Obesity showed that people who ate only during a six-hour window, compared to following a normal eating schedule, felt less hungry than the control group, even though both groups ate the same amount of calories. Intermittent fasting has also been linked to increased neuroplasticity , or the brain's ability to form new synaptic connections and fight injury.

Unfortunately, there hasnt been a ton of research on humans that follows the effects of intermittent fasting over the long term. While some studies have followed participants for a year, thats about as long as most go. Its a slightly different story when it comes to rats. In rodents, intermittent fasting has been shown to prevent age-related diseases including tumors, heart disease, diabetes, dementia, and even extend lifespan, says Keatley. But, he adds, there is a big difference between rats and humans and the research does not show these benefits enough to actually recommend it as the fountain of youth.

This is a huge perk of intermittent fasting: You technically dont have to alter what you eatyou just have to eat within a certain window of time.

That said, plenty of people have paired intermittent fasting with another type of diet, like keto. (Jenna, Halle, and Vanessa have all said that they do this.) Again, its not a requirement, but doing intermittent fasting while also altering your diet could help you get results faster.

There are a few things that can happen when you follow an intermittent fasting diet. One thing to note is that fasting can interfere with your hunger cues. Since people are only allowing themselves to eat in a certain window of time, they are completely ignoring their internal cues of hunger, Rumsey says. It causes people to disregard hunger cues, which then means once they are allowed to eat, they are starving and it can be hard to stop eating. This could lead to an unhealthy obsession with food for some people, Rumsey says.

Some fasters find that the diet makes them feel sharper and more alert, but alternately, fasting for long periods can also lead to mental fogginess, disrupted sleep, and decreased alertness, Rumsey says. And, she adds, fasting for extended periods of time takes a large toll on your blood sugar levels, causing you to flip-flop between low blood sugar and a spike when you eat again.

It really depends. If you feel like you have a healthy relationship with food and you do well with parameters, it could be a good fit for you. It's certainly not an easy diet if you hate the feeling of being hungry, but the fasting periods do get easier with time, Angelone says.

While anyone can try intermittent fasting, ultimately, people who are overweight and/or have high blood pressure or high cholesterol (but are otherwise healthy) are considered the best fits for the diet, Angelone says.

Theres really no magic plan to follow with this, but you could try to figure out a form of intermittent fasting that makes the most sense for you. The 5:2 diet can be tricky, given that it involves calorie restriction for an entire day at a time, so it might be better to start with something like the 16:8 diet and progress from there if you feel good.

You also want to define what youre hoping to get out of intermittent fasting, and it doesnt hurt to check in with an expert, like your doctor or a dietician, before you dive in. Work with a professional who understands your goals and can help you determine what you need to eat for a diet like this to achieve, says Keatley. Then, he recommends shooting for small changes and small gains as these are most likely to do the least harm and provide the most long-term benefits.

Above all, listen to your body. If you feel like youre hungry all the time and are kind of miserable on an intermittent fasting diet, it probably isnt the right fit for you. If you love the simplicity and you're seeing the weight loss or health results you want, fast away.