Start fasting like an expert with our 5:2 diet guide

“Eat 500 calories two days; eat normally the rest of the week.”

You’ve heard this before. 

One of your friends tried it once.

You know that Jimmy Kimmel dude is a big fan.

But you’re not entirely sure how it works, or if it’d suit you or your goals.

No worries. You’re in the right place. 

We’ll help you make an informed choice on whether the 5:2 diet is right for you, or whether you should give it a hard pass. 

5:2 intermittent fasting is easy to wrap your head around. 

  • 5 days a week, you eat as you typically would. 
  • The other 2 days, you fast. 

5:2 fasting days aren’t 100% food-free (yeah!)—you’ll eat roughly 25% of your usual daily caloric intake, around 500/600 calories.

As IF approaches go, 5:2 is pretty popular, and intermittent fasting has been around a long, long time. Some of the world’s greatest philosophers were into it, with Hippocrates, Plato, Socrates, and Aristotle all bigging up the benefits of fasting to both their thinky brains and their bodies. We’re willing to bet that these ancient Greeks also had glowing blood lipid panels and cholesterol levels. IF can do that for you.

Let’s dig into the details. 

Key takeaways

  • 5:2 fasting is eating 500/600 calories for 2 days and eating as you please the other 5. 
  • Hunger will happen, but it’ll pass and there are things you can do to help.
  • Eating protein, veggies, whole grains, and healthy fats, drinking lots of water, and exercising can help you thrive on 5:2. 
  • 5:2 fasting is great for weight loss and many people find it easier than traditional dieting.
  • 5:2 intermittent fasting can improve your blood pressure, insulin sensitivity, cholesterol levels, and brain health.

What is the 5:2 diet?

As far as “rules” go, a 5:2 diet plan involves only those two SIMPLE ones from earlier. 

During a 7-day week:

  • For 5 days, eat as you like. 
  • For 2 days, only 500/600 calories shall pass your lips. 

You see, the 5:2 diet isn’t a “diet” at all. It’s an eating pattern. 

This may seem like a semantic distinction, but it’s a helpful one (or at least it can be). 

Diets are often about restricting food groups and white-knuckling your way through day after day of eating like an undernourished sparrow. 

5:2 fasting isn’t like that. Quite the opposite, in fact. With 5:2, you can eat whatever you want

Sure, to get the most bang for your buck, you need to be mindful of your nutrition. And, it takes discipline to nail your 2 fast days.  

That said, there’s plenty you can do to make those things easier and embracing a wide range of foods is one of them. All the foods you love—and a bunch of new soon-to-be favorites, hopefully—are still on the menu. 

There are no “good” or “bad” foods with 5:2 fasting (or at all, in our eyes), just foods that work for you and foods that don’t. Construct your 5:2 diet to suit you: your lifestyle, your body, your goals, and your needs.

Building a healthy 5:2 diet plan

Can you follow a 5:2 diet plan while helping your body, mind, and spirit to thrive? 

Heck yeah! 

A SIMPLE tip: 

Leave at least one day between fast days.

To make this lifestyle sustainable—and so that you don’t hate life due to intense hunger—fasting days need to be non-consecutive. 

Makes sense, right? If you had the choice (and you do), you’d never go two days back-to-back eating only 500/600 calories. People wouldn’t be safe—two days in a row of modified fasting is enough to turn even the sweetest human into someone who descends into an uncontrollable rage (or at least heavy tutting) at their partner for breathing too loudly. 

Remaining a reasonable, upstanding member of society isn’t the only reason, of course. There’s no getting around it: Your body needs regular food. Eating enough matters, because undernourishment is a real thing that hurts your health. 

So, structure your fasting with care and smarts. 

Like this, for instance:

What schedule might work for you?

How to eat on fast days when doing the 5:2 diet

On the 5:2 diet, you are the boss of your food choices. 

As you construct your fasting menu, consider how different foods impact how you feel and function. Your choices will also make a big difference to how easy or hard you find it to get through a fasting day. 

One of the best ways to ensure feel-good, high-functioning vibes and smooth fasting: 

Eat nutrient-dense foods, like colorful veggies, fruits, whole grains, lean proteins, and healthy fats. Foods like these will help you feel full longer, reduce hunger, and stave off cravings.  

Soups and broths can be good options to help you feel satisfied and energized, as they’re super hydrating. Choose (or make) ones full of veggies and protein, like:

  • vegetable and barley soup with chicken
  • pumpkin and turkey chili
  • beef and root vegetable stews

By contrast, processed foods high in refined carbohydrates, sugar, salt, and unhealthy fats, like crackers, chips, pasta, white rice, or sweets are more likely to intensify your hunger and spark strong cravings.  

The bottom line: 

Make every one of your 500/600 calories work for its place in your fasting day menu. No free-loaders allowed!  

If this is all new to you, you might not be sure yet how filling the food you eat is. That’s OK. Explore different options and notice how you feel. 

And, if you need more support, we’re here to help. Try logging your food in our free SIMPLE app for helpful feedback on your meals, plus ideas on how to improve them.

A final tip here: 

When you’re fasting, stay hydrated. 

Fasting days can leave you feeling tired and headachey, so drink lots (our definitive guide on what you can drink while fasting will show you the best calorie-free options).

How to eat on regular days when doing the 5:2 diet

The same idea holds up on a non-fast day too. 

Make your foods work hard and shoot for nutritious choices, like fruit, fresh veggies, whole grains, and lean protein. 

Packing your daily menu full of foods that are:

  • high fiber
  • nutrient-rich
  • high protein
  • low calorie, high-volume

is key to keeping your appetite in check, your energy up, and your cravings under control. 

It’s also critical to getting as much benefit as possible from following your intermittent fasting 5:2 plan. 

Think about your goals for intermittent fasting. What do you want to achieve?

Build your food choices around that. 

So, if you’re 5:2ing for weight loss or to improve your health, these foods are your friends. Eat them often. 

Dealing with hunger and other possible negative side effects

We’ll be real with you: 5:2 can make you more hungry than other intermittent fasting protocols. 

However! The hungry stage should pass quickly. 

Make sure you:

  • drink lots of water 
  • eat high-volume, low calorie foods, like veggies and fruits, so you can eat plenty (while staying within your calorie limit on fast days)
  • learn how to distract your mind so it doesn’t get stuck thinking about food

There are many ways to hack hunger while fasting, and the three above will help a lot

5:2 fasting can also cause:

  • low energy
  • feeling cold
  • lack of concentration
  • headaches
  • dizziness 

All these will improve as your body adjusts, so don’t panic. Now you know what to expect, you can help yourself tolerate them in the meantime.

Dress warmly. When your energy is low, rest up. And, again, drink lots. Any dizziness, headaches, and low concentration will likely be eased by keeping yourself well hydrated. 

5:2 fasting for weight loss

For weight loss, 5:2 intermittent fasting is a proven method that gets results. In fact, research suggests that many people find it easier than traditional calorie-counting diets, because with 5:2 you only count calories two days out of seven. 

(SIMPLE top tip: planning your meals and snacks ahead of time can make it even easier.)

Studies also show that 5:2 fasting and traditional calorie-counting diets achieve the same amount of weight loss

If weight loss is the outcome you want, be mindful of the foods you consume and use 5:2 fasting to create a calorie deficit (simply, eating less calories than you burn). 

If exercise is your jam—or you want it to be—great! Intermittent fasting is even more effective when combined with exercise, so do both and see what you can accomplish.

Health risks and benefits of intermittent fasting 5:2

Aside from weight loss, what goodness could a 5:2 fasting diet bring to your life and your body?

Quite a lot, as it happens! 

Lower risk of type 2 diabetes

A growing body of evidence suggests that intermittent fasting can help lower the risk of type 2 diabetes, through reducing body weight and improving  fasting glucose, fasting insulin levels, and insulin resistance.

Improved insulin sensitivity

On a similar theme, this review showed intermittent fasting also improved insulin sensitivity. 

Lower risk of cardiovascular disease

This study suggests that intermittent fasting shows promising effects on the cardiovascular system, including lowering heart health risk factors like blood pressure and inflammation. Cholesterol levels also seem to benefit, and this 2021 review found that intermittent fasting was more effective than calorie restriction at reducing the risk of heart disease. 

Better brain health

Brains enjoy a little fasting action too, with studies demonstrating positive benefits on overall brain function and a reduced risk of cognitive disease

The evidence is growing, and encouraging. All that said, further research—particularly longer term and human-based studies—is still needed. 

The risks

5:2 isn’t 100% risk-free (heck, what is these days!?)

You may feel tired, weak, headachy, irritable, or struggle to concentrate. Perhaps you’re more moody than usual or have trouble falling asleep. 

And of course, there’s hunger. If it gets too strong, you can end up eating more than you need or want, and that can have a physical, mental, and emotional impact.

The good news is that all these effects tend to be short term and you have the power to mitigate them via the actions you take

Is the 5:2 diet safe?

It’s safe, but it’s not for everyone. We’d recommend you avoid 5:2 intermittent fasting if you:

  • have had an eating disorder or a history of disordered eating
  • are pregnant or trying to conceive
  • are actively growing (because you’re still under 18, you lucky thing)
  • have nutrient deficiencies
  • have health conditions, like type 1 diabetes or a thyroid disorder
  • have a BMI in the “underweight” category
  • have hypoglycemia (low blood sugar), and/or are prone to dizziness and fainting
  • experience mental health problems, like depression or anxiety
  • are on certain medications (for instance, for blood pressure or diabetes; to be safe always check with your doctor)

If you do decide to try it, talk to your doctor first and make sure you are fully supported by a health professional.  

Before we move on, let’s talk about intermittent fasting for men and women. For some women, intermittent fasting and hormones may not play nicely together, so be aware of the risks if estrogen and progesterone are in your hormonal mix.

Pros and cons of intermittent fasting 5:2

ProsCons
You choose what to eat Hunger and other side effects
Set your own fasting schedule Not suitable for everyone
It’s good for your health Takes some getting used to
A lifestyle, not a diet Not super intuitive

Pros explained

On the 5:2 diet, you choose your fasting days and no foods are off-limits. This means you’re in the driving seat of making 5:2 fasting fit your life. 

If you’re a social animal who loves eating with friends at the weekend, you can rock and roll, baby. Or, if you have a busy schedule on Monday and Thursday and just want one less thing to think about, you can hit your fast days then. 

Use your 5:2 routine to supercharge your health while living a full life as a well-rounded human. 

Cons explained

5:2 fasting takes a bit of getting used to and, honestly, it’s not right for everybody. 

You’re going to feel hungry and grumpy while your body adjusts. You might find it tricky to go against your appetite cues, but with practice, you’ll settle in (and avoid the rookie intermittent fasting mistakes that can disrupt your efforts). 

Is the intermittent fasting 5:2 method right for you? 

Only you can answer that.

5:2 fasting is right up your alley if…

  • the idea of fasting only 2 days out of 7 appeals to you
  • you feel able to hit 500/600 calories on each of those 2 days
  • it supports your health goals

If that’s you, give it a shot! 

If you like the idea of intermittent fasting but 5:2 leaves you cold…

… maybe a different option could work for you. 

5:2 fasting vs intermittent fasting 16/8 (other time restricted eating patterns are available)

With intermittent fasting 16/8, you’ll fast for 16 hours and consume all your calories in the remaining 8 hours. You choose your fasting periods; they’re shorter which makes hunger less of an issue; and you don’t need to count calories. 

This could be an excellent “Intro to IF” option, as could other time-restricted fasting approaches, like 12/12 or 14/10. On the other hand, 16/8 fasting is an everyday deal, and that may not jive as well with your lifestyle. 

5:2 fasting vs alternate day fasting (ADF), or 4:3

With alternate day fasting (also known as 4:3 fasting), you fast every other day and eat as you typically would on the days between. Like 5:2, not fasting every day might fit your life better. Though, there are more fasting days per week and hunger can be a real challenge. 

5:2 fasting vs one meal a day (OMAD)

OMAD requires you to fast for 23 hours and eat all your nutrients in a one-hour window. You can schedule your eating window any time that works for you, but it’s pretty restrictive. 

5:2 fasting vs water fasting 

Water fasting—where you only consume water for 24-72 hours—is a short term option. It’s an extreme protocol and truthfully, at SIMPLE, we don’t recommend you try it. 

SIMPLE’s expert opinion and final thoughts 

SIMPLE’s nutrition experts agree that if IF is safe for you, and you’re keen to improve your health and/or lose weight, 5:2 is an effective option that puts you in the driving seat. Expect the ride to be a little bumpy at first, but stick with it and you’ll see some real benefits.

If you need help figuring out your next steps, we’re here for you. Try out our quiz and we’ll guide you through the process of starting your IF journey.  

Frequently asked questions about intermittent fasting 5:2 

Is fasting twice a week healthy?

Yes, so long as you make sure to eat a nutrient-rich diet on your non-fast days. That said, “healthy” is a relative term and what works for one person may not suit another, so listen to your body and be guided by how you feel.  

Who should avoid the 5:2 diet, or intermittent fasting overall?

It’s best to avoid the 5:2 diet, or intermittent fasting overall, if you:

  • have had an eating disorder or a history of disordered eating
  • are pregnant or trying to conceive
  • are actively growing (because you’re still under 18, you lucky thing)
  • have nutrient deficiencies
  • have health conditions, like type 1 diabetes or a thyroid disorder
  • have a BMI in the “underweight” category
  • have hypoglycemia (low blood sugar) and/or are prone to dizziness and fainting
  • experience mental health problems, like depression or anxiety
  • are on certain medications (e.g. for blood pressure or diabetes; always check with your doctor)

How much weight can you lose a week on 5:2? 

This review found intermittent fasting led to a typical weight loss of 7-11 lbs. (3-5 kg) over 10 weeks. While it likely won’t be this linear, you can lose between 0.5-1 lb. (0.2-0.5 kg) a week on 5:2 (a safe, sustainable rate). 

Does the 5:2 diet have to be consecutive days? 

Not only does the 5:2 diet not have to be consecutive days, we’d highly recommend it isn’t! Trust us on this one; it’ll make for a much more pleasant experience if you put 1–3 non-fast days between your fasts. 

Can you exercise on fasting days on the 5:2 diet

Can you exercise on fasting days on the 5:2 diet? Absolutely! Listen to your body, pay attention to your energy levels, and notice how you feel. Get used to your 5:2 routine before you add fasted exercise in and go easy on the intensity at first.

How long should you fast for on 5:2?

Your goals will determine how long you fast for on 5:2. Once you’ve reached your goals, you can always switch out to a higher calorie intake on fast days, or to a different IF plan like 12/12 or 14/10, in order to maintain the benefits you’ve seen. 

How long does it take to see results on the 5:2 diet

How long it’ll take to see results on the 5:2 diet depends on you. 

Your results will be influenced by many factors, like stress, sleep, what you eat, how you move, your age, lifestyle, and so on, but your actions are key. Stick with your plan, make wise food choices, and you’ll see swifter results.

Does the 5:2 diet really work? The science suggests so! Although more research would be welcome, there’s strong evidence to say that the 5:2 diet does really work. Whether it’ll work for you… try it and find out! Get started here.