Intermittent Fasting – A Beginner’s Guide

What is intermittent fasting?

Intermittent fasting has recently become a popular method designed to help you lose weight, improve your health and overall well-being and in particular your gut health. Each intermittent regime differs slightly, but in general this involves only eating at certain times of the day or during certain days of the week.

According to a survey by the International Food Information Council Foundation, intermittent fasting was last year's most popular diet trend. There are many ways you can fast, each of which involves regular intervals where you can only eat at certain times throughout the day.

What are the benefits of intermittent fasting?

Giving your body time to rest between meals allows your body to repair itself and function better. In addition to reducing your body weight, fasting can also help improve your glucose control, reduce liver fat and improve your blood pressure. This makes intermittent fasting a great option for improving your overall health and well-being, as well as losing weight.

Studies have also shown that eating according to your circadian rhythm i.e. eat in the day and sleep at night, helps promote deep sleep and can also increase your lifespan. Long term, it could even reduce your risk of tumour growth and help prevent recurrences of breast cancer.

Switching to an intermittent fasting routine has many benefits, including:

  • Boosting weight loss
  • Increasing your energy levels
  • Improving your sleep
  • Making your cells more resistant and helping cellular repair
  • Reducing insulin resistance and protecting against type 2 diabetes
  • Lowering bad cholesterol
  • Improving memory and boosts brain function

What types of intermittent fasting are there?

There are a few different types of intermittent fasting options available and it’s good to weigh up and discuss with your doctors which options work best for you.

If you decide that intermittent fasting is something that you feel will benefit your health and it’s safe to go ahead, the most popular methods are:

  1. The 5:2 diet

    This is the most popular intermittent fasting plan, where you only consume 500-600 calories on two days of the week (non-consecutive) and then eat normally for the remaining five days.

  2. The 16/8 method

    This involves skipping breakfast and restricting your daily eating period to eight hours then fasting for 16 hours in between. E.g. only eating between 12pm – 8pm. To start with if this is too much of a stretch you should look to try a 12/12 fast.

  3. Eat-stop-eat

    This intermittent fasting plan involves you fasting for 24 hours once or twice a week.

Reducing the times you’re allowed to eat is a good step to improving your health and kickstarting weight loss, as long as you don’t overcompensate by eating too much during the time you’re eating and that you try to introduce healthier eating habits, such as eating more vegetables and reducing processed foods.

How long should you fast for?

There is no set amount of time for intermittent fasting, but it should be treated as a way to kickstart your diet and improve your lifestyle, not a life-long process. As a guideline, a reasonable intermittent fasting programme should last between 6 weeks to 6 months.

Tips for intermittent fasting

It can be really challenging to try and stick to an intermittent fasting regime, so hopefully our tips will help you stay on track so you can get the most out of your fast.

Stay hydrated

Drinking lots of water and additional calorie-free or low-calorie drinks like herbal teas throughout the day can help curb hunger and keep you focused on day-to-day tasks whilst at work or during any activity.

Eat nutrient-rich, low-calorie foods

A good way to make every calorie count whilst intermittent fasting is to eat a selection of nutrient-dense foods that are rich in protein, fibre, vitamins and healthy fats such as eggs, fish, nuts, vegetables and fruits with high water content like grapes and melons.

Seasoning meals with garlic, herbs and spices is also a good way pack your food full of flavour without adding too many calories to your meals.

This will help keep your diet interesting and meals tastier and will help keep you fuller for longer and refrain from processed, unhealthy food and snacks.

In addition to weight loss, eating a healthy, varied diet will also help your overall health, especially for things like keeping your blood sugar levels steady and preventing any nutrient deficiencies.

It’s also important not too obsess too much over food and judge yourself if you do eat something that’s not necessarily as healthy as it could be, as you can always try again during your next period of eating.

Plan ahead

For some intermittent fasting options, such as the 16:8 diet, it’s easier to plan your day, as most of the time you are fasting you will probably be sleeping. However, if you’re on the 5:2 diet, there will be full days when you are fasting, which can be more challenging.

For these days, it’s best to try and plan ahead and prevent taking on too much on those days. If you can, rest and relax on these days and avoid strenuous activities.

Can you exercise when intermittent fasting?

It is safe to workout when fasting, but there are a few things to consider. Firstly, fasting long-term could slow down your metabolism, so there are debates as to whether you may actually burn more fat or not by working out and fasting. Plus, you may also lose muscle mass or only be able to maintain what muscle you have, rather than build more muscle.

Strength workouts tend to require more carbohydrates than cardio or high-intensity interval training (HIIT) which can be done on a lower carb diet, which is another important factor to consider if your aim is to lose weight from fasting.

Another downside to fasting and exercising is that you might not perform as well during workouts, so it is best to stick to low intensity, short duration workouts rather than push your body too hard when fasting.

Timing is also important here. Working out before your window of eating is fine if you’re used to exercising on an empty stomach, but if you’d like to eat following your workout, it’s best to time your workout during your window so you can enjoy a protein-fuelled dinner afterwards.

Overall, it is safe to exercise but just make sure you stay hydrated, time your meals right and most importantly, listen to your body. If you’re feeling overwhelmed or really weak when working out, consider cutting back on exercise or opting for less intense workouts while you fast.

Light exercises and stretches such as yoga may also be beneficial, especially for days when you’re fasting.

Are there any side effects to intermittent fasting?

Like all diets and regimes, intermittent fasting isn’t without its side effects. These include:

  • Feeling tired, weak and irritable when your body is trying to adjust to your new routine
  • Experiencing lots of hunger, especially at the beginning
  • Risking overeating during the hours you’re allowed to eat

It’s worth taking note and considering the side effects before you commit to fasting, as it could interrupt your daily life, such as driving and working when you feel weak and tired.

Overall, intermittent fasting has many benefits, which can certainly help you start to live a healthier lifestyle and help you reach your weight loss and well-being goals. As always, we recommend speaking with your doctor to see if this is a good option for you before you start your fast.

Information contained in this Articles page has been written by talkhealth based on available medical evidence. Our evidence based articles are accredited by the PIF TICK, the only UK quality mark for trustworthy health information. The content however should never be considered a substitute for medical advice. You should always seek medical advice before changing your treatment routine. talkhealth does not endorse any specific products, brands or treatments.

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Information written by the talkhealth team

Last revised: 26 September 2019
Next review: 26 September 2022