Is intermittent fasting good for weight loss?

Alarm clock next to dinner plate

Losing weight is a common New Year resolution, but it can be so tricky to stick to.

Whether you're looking to drop a couple of pounds caused by one too many mince pies over Christmas or you're planning on hitting a major weight loss goal in 2021, it can be difficult to know where to start.

Intermittent fasting has been a growing weight loss trend that has been endorsed by medical professionals, such as Dr. Michael Mosley and Dr. Jason Fung.

How does it work and could it be beneficial for your weightloss journey?

This is your intermittent fasting guide where you will find everything you need to know about how it works and whether it could work for you.

How intermittent fasting works

Although it is now having its time in the spotlight, intermittent fasting has been used for weight loss in different forms for a long time.

It was Michael Mosley's TV documentary 'Eat Fast, Live Longer' and book 'The Fast Diet' that thrust intermittent fasting into the public eye in 2012.

Variants of intermittent fasting have since been developed by people such as Dr. Jason Fung and journalist Kate Harrison, which has been based on their experiences using this weight loss method.

Whichever form of intermittent fasting you choose, the principle is the same.

It is essentially a schedule where you switch between fasting and eating.

Fasting may sound scary and the word can conjure up images of feeling constantly hungry or shaky through lack of food.

However, our bodies can naturally go through long periods of time without food, which makes intermittent fasting a safe (depending on your health and whether you have any underlying conditions) and effective weight loss solution.

How does intermittent fasting burn fat?

We eat food to give us energy.

Our gut contains enzymes, which break down the food we eat to release molecules that perform certain duties within the body.

Carbohydrates are broken down into sugars, which our cells use for energy, but if our cells don't use up all of these sugars, we store it as fat.

Let's imagine our cells are a really cool, but exclusive club.

The sugar that has been created from carbohydrates wants to enter this exclusive club, but it can't get in without a 'ticket'.

This 'ticket' is insulin, which is a hormone created by the pancreas and allows sugar from our food to enter our cells.

The principle of intermittent fasting is to decrease insulin levels so less of these sugars enter our cells for long enough that sugars that are already being stored as fat can be burned off.

Which intermittent fasting times work best?

Even though the principal of intermittent fasting is the same whichever way you do it, there are different methods you can implement into your lifestyle depending on your needs.

Fasting doesn't necessarily mean not eating at all and it doesn't have to be for long periods of time.

The key thing to consider when trying intermittent fasting is which method would be best for you?

Could you spend a couple of days a week eating around 500 calories per day?

Would you be able to go for a period of a few hours every day without food?

The main forms of intermittent fasting are:

  • Alternate day fasting (ADF): where you fast on alternating days and eat as much as necessary on other days
  • 5:2 diet: probably the most well-known form of intermittent fasting, where you spend 5 days eating a balanced diet and 2 days on a reduced calorie intake of around 500-600 calories
  • 16:8 intermittent fasting: you eat exclusively within an 8 hour window and fast for the remaining 16 hours of the day
  • 24 hour fast: this involves spending one day, either weekly or monthly, fasting

All methods can help you to lose weight, but like all weight loss methods, this isn't a one size fits all scenario with one particular method being the best.

If you are a beginner, the 16:8 method is one that could be most easily incorporated into your lifestyle, as it is the least severe.

Simply pick an 8 hour eating window based on your lifestyle and ensure you do not consume any calories after this window.

An example would be to consume food between the hours of 9am and 5pm and not eat anything until 9am the following morning.

What are the health benefits of intermittent fasting?

There haven't been enough studies on intermittent fasting to show if it is effective or safe for long periods of time, but it can help to kick start your diet and, as long as you have no underlying health conditions that could be affected by intermittent fasting, it shouldn't cause any harm in the short term.

If you are overweight or obese, studies have shown that intermittent fasting can help you to lose more fat compared with conventional dieting.

It may also help you to have greater control over cravings and you may worry less about feeling hungry, as your body gets used to your new regime.

Can intermittent fasting help IBS?

There hasn't been a great deal of research into whether intermittent fasting can help digestive issues such as IBS.

However, some people have found that intermittent fasting has helped to regulate their digestive system and has made their bowel movements easier to manage.

If you have IBS, it is recommended that you seek advice from your doctor before attempting intermittent fasting to ensure that it is suitable for you and to find out if there are any extra steps you need to take to ensure you are fasting safely and to protect your health.

Is intermittent fasting better than other diets?

Studies have shown that, when done properly and using a method that suits your lifestyle, intermittent fasting can be just as effective, if not more so, than conventional dieting.

Intermittent fasting isn't a diet, rather a lifestyle change that you need to stick to in order to gain results.

This can be good in some ways, as you will need to consider what foods you are consuming on your non-fasting days in order to fuel your body effectively.

Just because you have fasted the day before doesn't mean you can fill your non-fasting day with pizza and burgers, as you are not likely to see effective results and you may end up feeling sluggish and lacking energy.

One major drawback is severely restricting your calories or not eating at all for a period of time can be tricky to maintain if you have never done it before and it takes willpower and determination.

If you know that you lack discipline when it comes to food and you're not likely to be strict with yourself when fasting, this may not be the method for you and it may leave you feeling dejected if you feel that you can't stick to it.

The important thing you need to remember when you embark on your weight loss journey is that weight loss doesn't mean you have to punish yourself.

The key is finding a method that suits your needs, lifestyle and personality.

Intermittent fasting vs calorie counting

If you know that you can't go for long periods of time without eating something, then intermittent fasting may seem daunting.

Calorie counting involves setting a calorie limit to ensure you are eating within a calorie deficit.

Eating within a calorie deficit means your body burns more calories than you consume which leads to fat being burned off before it can be stored.

There are no limits on when you can consume these calories, as long as you don't exceed your calorie limit during the day.

Calorie counting is an effective weight loss method if you don't like the thought of going without food,  but it can also be a bit of a faff.

When out and about in restaurants or cooking food from scratch, if the calories aren't listed on the menu or in your recipe, it can be a bit of a pain to work it out and ensure you're keeping on track without going over your limit.

If you follow an intermittent fasting method, such as 16:8, you won't have to religiously count your calories (as long as you're eating a healthy diet and not binging on unhealthy food) and you could choose the 16 hour time slot around a time that you wouldn't normally eat a lot anyway, such as 5pm - 9am where most of the hours will be spent sleeping.

Intermittent fasting vs Keto

Keto is another weight loss trend that has been in the spotlight in recent years, as it has been endorsed by many a celebrity.

However, most celebrities aren't nutritionists, so let's look at the facts.

A keto diet is a big commitment and not a method that should be experimented with.

The principle of this diet is to force your body into relying on ketone bodies (a substance created by the liver from stored fat) as fuel rather than sugar from carbohydrates. 

It requires you to cut out carbohydrates and eat fat at each meal, including high amounts of saturated fats, which we all know is a big risk factor for heart disease - not ideal!

It can also increase the risk of nutrient deficiencies, problems with your liver and kidneys, constipation, as well as cause issues with our mood and mental health. 

Even though keto has been promoted as a weight loss method, only short-term studies have been conducted and results have varied regarding how successful and safe it is as a weigh tloss diet. 

Cutting one particular food or food group from your diet can also be problematic when dieting, as it can cause you to crave it and limit the success of your diet.

Intermittent fasting doesn’t pose any restrictions on certain food groups or place any demands on you to eat a lot of a certain food group. 

As long as you are eating a varied, balanced diet on your non-fasting days which involves all food groups in moderation, you don’t need to worry about cutting out certain foods. 

Who shouldn’t do intermittent fasting?

Although intermittent fasting can be useful for some people it is not recommended for those with certain conditions or history of medical issues.

Those who are underweight, have or have had an eating disorder or have a history of serious mental health problems shouldn’t do intermittent fasting.

This is because it involves restricting the amount of food that you consume each day which can be triggering if you have suffered or currently suffer from an eating disorder or mental health problem.

Children under 18 years old shouldn’t incorporate intermittent fasting into their lifestyle as this could affect their growth, development, health and mental wellbeing. 

It could also start an unhealthy relationship with food if they feel they have to restrict themselves, which could lead to eating disorders and mental health problems.

Those who have underlying medical conditions, are frail or are on medication should always seek advice from their doctor before using any weight loss method as dieting could be harmful to their health. 

If you take Warfarin, intermittent fasting will not be suitable for you as varying the amount of food you consume can interfere with your international normalised ratio (INR).

Can I do intermittent fasting if I am pregnant or breastfeeding?

It is not recommended to take part in intermittent fasting if you are pregnant or breastfeeding as it may deprive you of necessary calories and nutrients that both you and your child need in order to be healthy.

There is also the risk of your blood sugar falling too low if you fast whilst pregnant, which can be harmful to both you and your baby. 

Can I do intermittent fasting if I am diabetic?

It is not recommended to do intermittent fasting if you have type 1 diabetes or if you take medication for diabetes as intermittent fasting reduces the amount of insulin carrying sugar to your cells.

It can also cause your blood sugar to decrease which can be incredibly harmful if you have type 1 diabetes.

If you are looking to lose weight and you are a diabetic, speak to your doctor for recommended diets and lifestyle changes that are suitable for you. 

So, there we have it.

This is all the basic information you need to know about intermittent fasting.

Whether you’re planning on trying intermittent fasting or another form of diet, Chemist4U have a range of weight loss products available, including SlimFast and Celebrity Slim which can be used to form an intermittent fasting regime.

Olivia Appleton - Medical Content Writer
James O'Loan - CEO & Superintendent Pharmacist
James O'Loan , CEO & Superintendent Pharmacist on 17 September 2021
© 2024 Chemist4U. Innox Trading Ltd, 35-37 Greenhey Place, Skelmersdale, Lancashire, WN8 9SA, GB. All rights reserved. Registered and regulated UK pharmacy with the GPhC (registered premises 9011784). Registered in England No. 07262043 | VAT Registration No. GB140138454