Intermittent Fasting: What Is It? Should You Do It?

Intermittent fasting is a hugely popular fasting method being picked up by more people than ever – including pro athletes around the world.

For most, it’s an effective way to achieve a calorie deficit but it also comes with many questions. For example, does it work? And most of all should you do it?

We’ll answer all these and more so you can find out whether to give it a try or not.

Let’s start with the basics. What is intermittent fasting?

What is Intermittent Fasting (IF)?

Fasting has been around for centuries and is often done for religious or spiritual reasons. In fact, in some cultures, fasting is seen as more normal than eating three or four meals per day.

Intermittent Fasting is an eating pattern rather than a diet. During the ‘feeding window’ you can eat whatever you like – as long it’s part of a healthy, balanced diet.

If you intermittent fast you don’t eat for an allocated period of time, typically hours or days, and then you have set hours to fill up on calories for that day. Many intermittent fasters don’t count calories, but they do take in a healthy diet full of essential macros. With this fasting plan, you still have to eat healthily – feasting on hamburgers and pizzas during your feeding window won’t help with weight loss.

Intermittent fasting is a way of scheduling the meals you eat so that you get the most out of them. There’s no need to stick to restricted time frames – you could fast for as little as six or eight hours, or go for a full day or more. It all depends on the type of intermittent eating plan that you choose.

This doesn’t mean you can eat as much as you want on an IF diet though, just that you have the flexibility to eat what you want within a pre-set, calorie-controlled window.

Numerous studies have shown intermittent fasting may have a powerful effect on your body and may even extend life expectancy12. A growing body of evidence also suggests that the timing of intermittent fasting is key, and may make it a more realistic and sustainable approach for weight loss and for diabetes prevention3.

Let’s discover the different methods.

Intermittent Fasting Methods

There are many ways of doing intermittent fasting. These are considered the most popular methods:

16/8 Method

Newcomers to intermittent fasting might want to give this approach a try because of its simplicity. All you have to do is choose eight hours of the day where you can eat – then fast for the rest. That means no eating or drinking anything with calories in it during that fasting window.

For example, you might decide to eat between the hours of 12-8 pm. Once you’ve finished your food, you’ll not eat anything again until 12 noon the next day. You can repeat the cycle to once or twice a week, or every day.

Many people who’ve tried this method say it is the most sustainable and easiest to stick to. This is because it’s considered a lot less restrictive and can be easily modified to fit into just about any lifestyle.

5:2 Method

The 5:2 method – also known as ‘The Fast Diet’ – was popularized by British journalist Michael Mosley. It requires you to count some calories because you spend at least two days of the week only eating between 500-600 kcals.

People are recommended to consume a ‘normal’ number of calories for five days a week and then for two, non-consecutive days, eat just a quarter of their usual calorie intake – this is usually 600 calories for men.

There are no limits on the type of food you eat and you don’t need to exclude any food groups. However, it makes sense to follow a healthy, plentiful diet on your ‘normal calorie’ days. When it comes to choosing your days, we recommended you avoid fasting on two consecutive days – instead split your week up, for example, by fasting on Monday and Thursday – this may help prevent fatigue.

Alternate Day Fast or Eat Stop Eat

This method is up there as one of the most popular ways to intermittent fast. The variability is where you have a ‘modified’ fast every other day. For example, you can limit your calories to 500 on fasting days and then go back to your normal healthy diet the next day. With it, you only need to restrict what you eat half of the time.

With this fasting method, some people even go the extra mile and totally restrict themselves of food on alternate days, for a whole 24 hours.

As you can see, there are lots of way to try intermittent fasting. We don’t believe there are any that are necessarily better than the other, but it all comes down to personal preference – and whether it’s a fasting plan you can stick to.

We’d suggest you try the 16/8 method first as most people find it the easiest.

Weight Loss & Intermittent Fasting

Losing weight is one of the main reasons anyone would want to give intermittent fasting a try. And no wonder – its weight loss benefits come with the scientific evidence. Intermittent fasting simply allows the body to use its stored energy, for example, by burning off excess body fat4.

Research backs up many claims that fasting can help a person lose weight. Many people see increased loss of visceral body fat and reduction in bodyweight compared with those who just use normal calorie reduction diets5.

Scientists even suggest that using intermittent fasting eating patterns can result in a 3-8% weight loss over 3-24 weeks6. The same study showed that people cut their waist circumference by 4-7%, demonstrating a major loss of harmful belly fat that can build up around the organs and cause disease.

Intermittent fasting is said to be effective for weight loss as it helps you cut back the calories you consume and essentially puts you in a calorie deficit. The less time you have to eat, the more weight you may lose.

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Side Effects of Intermittent Fasting

Trying something new in terms of your nutrition doesn’t come without its side effects. However, reported side effects with intermittent fasting tend to fade within a few days. As you may expect, hunger is the most common side effect, with fatigue a close second. You may also feel weaker as your body takes time to adapt to your new nutrition schedule.

Other side effects of IF include:

  • Food cravings
  • Headaches
  • Constipation
  • Diarrhea
  • Interference with medical conditions

In all, intermittent fasting is regarded as one of the safest weight loss methods available. Always speak to a healthcare professional if you’re ever unsure about starting a new diet or nutrition plan.

Intermittent fasting
Health Benefits & Effectiveness

As recognized, intermittent fasting is most beneficial for weight loss. However, there are additional potential benefits beyond this.

Here are some of the health benefits associated with IF:

Reduced insulin resistance

If you’re worried about developing type 2 diabetes, intermittent fasting could help with that. This style of eating has been shown to hugely benefit insulin resistance and lead to a reduction in blood sugar levels7.

Lower levels of insulin in the blood can also help facilitate fat burning8.

Fights inflammation

Intermittent fasting can also contribute towards reducing oxidative stress and inflammation – one of the biggest causes of many chronic diseases9. Inflammation can lead to various diseases including diabetes, multiple sclerosis and inflammatory bowel syndrome.

IF may boost your body’s resistance to free radicals which damage important molecules in the body10.

May benefit heart health

Four major risk factors for heart disease include high blood pressure, cholesterol, diabetes and weight.

Intermittent fasting may play a part in reducing these factors, lowering harmful LDL cholesterol, blood sugar and insulin resistance – therefore benefiting heart health11 12.

Another positive thing about intermittent fasting is that it doesn’t appear to cause as much muscle loss like calorie cutting would normally do13. As such, it could help you keep those hard-earned gains while reducing extra body fat.

Should You Do It?

Deciding whether to try intermittent fasting comes down to personal preference as well as your fitness and health goals. Ask yourself: does it suit your lifestyle? Will you be able to handle the initial days where you might get those hunger pangs?

Consider if it will put your health at risk or help you on your fitness journey.

Intermittent fasting is a popular weight loss method – and for good reasons. The health benefits are clear to see and the science says it works. So, if you’re struggling with conventional calorie cutting or you lead a busy life, intermittent fasting might be for you. You could approach IF by fasting whenever it is convenient – skip meals when you’re not hungry or don’t have time to cook.

It’s important to bear in mind that, though IF is safe for most healthy, well-nourished people, it may not be suitable if you have any medical conditions. For this reason, it’s wise to speak to your healthcare provider before starting on an intermittent fasting plan.

This is especially important if you:

  • Take medications
  • Have diabetes
  • Are underweight
  • Have issues with blood sugar regulation
  • Have low blood pressure
  • Have a history of eating disorders


Can I drink during intermittent fasting?

Yes, you need to stay hydrated when you are intermittent fasting but you should avoid drinks like soda or juices. These drinks are packed with calories and can break your fast.

What can you eat or drink while intermittent fasting?

We recommend that you drink lots of water when intermittent fasting. Water is great for helping you feel full and some research says it may also suppress the appetite14. Green tea, black coffee, bone broth are all also good options when you’re fasting. To avoid breaking your fast do not add sugar to your coffee or tea.

In terms of food, intermittent fasting does not restrict you from any food groups so essentially you can eat what you want when in the feeding window. However, it wouldn’t make sense to binge on junk food and high calorie foods – instead opt for a plentiful, nutritious diet full of fiber, protein and healthy fats.

Can I take supplements while fasting?

As a general rule of thumb, you can continue to take supplements while intermittent fasting. However, you should be mindful of how they may affect your body during your fast. Some may not be absorbed and may make you nauseous when taken on an empty stomach.

Taking supplements while fasting may take some experimenting. Some supplements like vitamin D and A may need to be taken at certain times of the day or with food so that you can get the most out of them.

How long should I do intermittent fasting to lose weight?

Much of the research we’ve examined seems to suggest results can vary with every person. That said, you should see some weight loss results at around the three-week mark. Some experts say you should follow the basic intermittent fasting rules for 10 weeks to see significant changes.

The Bottom Line

Intermittent fasting appears to be an effective solution to lose weight and improve overall wellbeing. There are many ways to try it so find out what works for you. This is ideal since we’re all different and there is no ‘one-size-fits-all’ solution when it comes to IF.

Like with any sort of diet change, intermittent fasting does have its drawbacks and can have side effects. For this reason, it’s important not to take IF to the extreme if you have a long-term illness or a history of eating disorders.

That said, many people report positive results when intermittent fasting. If you’re interested in trying this type of eating pattern, take the time to find your perfect plan. Try a few of the variations and see how each method makes you feel.