How Intermittent fasting helps you burn belly fat and lose weight

Intermittent fasting, or IF, has been center stage in the weight loss and nutrition world for the last few years. There's a lot of hype around what time restriction schedules to try! Part of the feverish excitement around it lies in the fact that it is backed by science, with real medical and health benefits. 

So let’s get down to the skinny on IF. 

What is Intermittent fasting?

Intermittent fasting wasn't really a thing even as recently as 50 years ago, because people naturally went to bed around 11pm. The rise in all day entertainment through technological advances means that nowadays we often stay up late, we eat meals and snacks well into the night and often in distraction mode.

The energy obtained from the food we eat often exceeds the energy requirements of our bodies. Our cells then store the excess energy as fat, which sits under the skin layer and surrounds our vital organs. An excess build up of this fat can lead to chronic lifestyle conditions such as high blood pressure, obesity and type 2 diabetes. 

Intermittent fasting is a time restricted eating pattern which works by using when you eat to help with weight and energy regulation. It splits the day into 2 sections: the eating phase and the fasting phase. The 2 phases use different sources of energy to power your body.

The eating phase: The time period where you consume all your daily food. Your food and the glucose it is broken down into provides the energy for this time period.

The fasting phase: A period of time where you fast, allowing your body to start melting down body fat and using that as the main source of energy. 

Choosing an Intermittent fasting plan that will help with your weight loss

There are 4 common types of intermittent fasting schedules. During the fasting period, you abstain from food, although liquids such as water and plain coffee (no milk and sugar) or tea are generally fine. 

16/8

This is the most common IF plan. 

Eating phase: 8 hours

Fasting phase: 16 hours

This method has shown promise in overweight and obese people as an effective weight loss method. However, studies haven’t found that it is more effective than continuous caloric restriction. Using this methodology might help with creating a eating rhythm, as well as aiding with fat loss.

Fasting for 16 hours also has significant effects on lowering insulin production and blood glucose levels in the body - which is great for the prevention of type 2 diabetes. 

14/10

Eating phase: 10 hours

Fasting phase: 14 hours

This plan was found to be more appropriate for women than men, given hormonal differences between the two genders. It also works better if you are someone who enjoys working out in the morning, given that the energy requirements for a workout lead to more energy expenditure.

The downside is that to lose weight, you must achieve a calorie deficit (the energy you use must be more than the energy you consume with your food). As the 14 hour fasting period mimics what most people naturally do, eating all calories within 10 hours may not necessarily lead to a caloric deficit - meaning the results may be slower. 

This may be the perfect plan for beginners, or those looking to achieve slow and steady weight loss and health benefits without compromising on hunger levels. 

5/2 

Eating days: 5 days

Fasting days: 2 days

This intermittent fasting schedule works by eating normally 5 days of the week and for 2 days, following a calorie restriction fast. Females consume 500 calories, while males consume 600 calories on the fasting days. It works best when the days of fasting are spaced out throughout the week. Research shows that this intermittent fasting plan is as effective as traditional calorie restriction diets for weight loss. 

Alternate day fasting 

Eat one day, fast the next.

Some plans involve complete fasts for 24 hours, while others use the fasting day to consume 600 or fewer calories.

However, the evidence on this methodology is unclear - there have been no conclusive studies demonstrating the effectiveness of this method.

As well, fasting for 24 hours can have dangerous side effects, and is not suitable without appropriate medical guidance. 

At the end of the day, the best intermittent fasting schedule to help you lose weight and burn fat is the one you are able to maintain long term. As with any healthy eating change, if it is not sustainable, then the benefits become negligible. Additionally, combining intermittent fasting with a high nutritional value diet and exercise regime will exponentially increase the likelihood of positive results. 

How Intermittent fasting works to help you burn belly fat

Our bodies have evolved through the ages to suit a hunter and gatherer lifestyle. This means that our systems have been designed to withstand periods of fasting, which our ancestors needed to get to the next food source without wasting away. 

Imagine that there are little workers inside the machine that is your body, working to provide you with all the energy you need for daily tasks. They are split into 2 groups.

The first group, lets call them EAT, starts their shift when you are in your eating phase. During this phase, they take all the glucose from the food you eat and send it whizzing around your body to allow all your body’s processes to function. 

If you eat in excess of your energy needs, the EAT’s prompt the pancreas to release insulin, a hormone that sponges up all the glucose floating aimlessly in the blood stream, and transport it to the liver to be stored as fat. 

Once you enter your fasting phase, the amount of glucose the EAT group has to play with dwindles down to zero, because you aren’t eating anything, therefore not providing them with anything to break down. So they clock off, and the second group comes in.

This group, known as the FAST’s, enacts the metabolic switching spell, and activate a process called lipolysis in the body.

Lipolysis is the breakdown of fats. Not just any fats - the fats that are stored in the fat deposits of your body. Those are most commonly found in the belly, thighs, arms and butt. Through this process, your body produces ketones - the alternative energy source to glucose. The FAST’s maintain this energy until you start to eat again. Then their shift ends, and the EAT’s take over. 

If we take out the characters, it works like this

You eat - your body takes the carbohydrates from your meals and converts them into glucose, which is used as the main energy source. Any excess glucose is taken up by insulin and stored in the fat cells of the body.

You fast - your body has no carbohydrates to works with and so begins to break down the fat stores that are there for periods where you have no access to food. By doing so, you produce ketones, which are then used as energy until you consume your next meal. 

This process is called metabolic switching.

A 2011 study demonstrated that up to 79% of the weight loss experienced by participants of a intermittent fasting plan was fat loss, indicating that it has a place in obesity treatment.

The most common place where most people store their fat is the belly. Thus, intermittent fasting can help you lose belly fat by enacting metabolic switching and allowing your body to use a your stored fat cells as an energy source. 

The benefits of Intermittent Fasting for losing weight and burning body fat

Sustainability

Intermittent fasting is easy to achieve if you modify it to suit your daily pattern. For example, if you are someone who habitually skips breakfast, you may be able to do a 16:8 IF schedule quite easily by having an early dinner and then skipping breakfast the next day! 

Better insulin sensitivity

When you partake in an intermittent fasting plan, your insulin levels drop significantly, allowing your body to enter a state of ketosis and promoting fat burning. 

As your body starts getting more sensitive to glucose influxes happening in your body, your chance of insulin resistance starts to reduce, which directly reduces your risk of type 2 diabetes. 

Keep in mind, this may be gender specific, as a 2017 meta-analysis indicated that women on an intermittent fasting schedule for 3 weeks actually showed worse insulin sensitivity. 

Increased human growth hormone (HGH) and norephinephrine

Don’t worry, you aren;t going to shoot up like a bamboo pole. Increased levels of HGH and norepinephrine increase your level of fat burning and your body’s utilisation of fat as energy. This is why short term fasting can be really beneficial for fat burning

Loss of subcutaneous fat

Subcutaneous fat is the fat layer that lies just beneath the surface of the skin. It accounts for about 90% of body fat. The other 10% is made up of visceral fat - the fat that surrounds your organs. 

During intermittent fasting, subcutaneous fat is the type that is being lost through the mechanism outlined above. This is generally the type of fat that people prefer to lose, as it is the one visible to the outside world! 

There are studies demonstrating that visceral fat actually becomes more resistant to being broken down in periods of fasting. This makes sense - fasting indicates scarcity of food, and as the body’s main function is survival, maintaining and slowing down the breakdown of the vital fat that protects our organs is beneficial from a survival perspective. 

Improved heart health

There are several markers for heart health that have been shown to significantly improve in patients  on intermittent fasting plans. 

These include:

• LDL

• HDL

• Triglycerides

• Blood pressure

• Blood sugar levels

As heart health is one of the leading causes of death in the developed world, again, this indicates that intermittent fasting may have a place in the prevention of this condition

The Risks of intermittent fasting

No long terms studies

Intermittent fasting is very effective, definitely, but the long term effects have not been studied. 

Because intermittent fasting promotes the idea of effectively putting the body into starvation mode, there may be risks associated that will only be discovered in retrospective studies. 

Due to this, it is highly recommended that if you are thinking about starting an intermittent fasting plan, you discuss this with a health care professional.

Rebound Weight gain

If the plan isn’t sustainable, it’s not a good plan. That’s because of the rebound weight gain phenomenon associated with most, if not all short term weight management programs. 

This is something I warn all my patients and clients about. Studies around fasting, using medication for weight loss, and intense calorie restriction protocols in the short term almost always show a result of rebound weight gain, up to 10% more than the starting weight! 

A 2023 study found that intermittent fasting done as a short term strategy, or taken to extremes such as 20 hours fasting can actually promote weight gain once completed, as it slowed down metabolism in the long term. 

This is almost identical to data found over the last 2 decades on weight loss strategies that are not sustainable. Fad diets, meal replacement programs, using medication for weight loss and restrictive protocols all have this as a side effect, and it is important to take this into account when going into any healthy eating change. 

If you don’t plan your meals with the end goal of transitioning back into a normal eating pattern, then you are bound to experience this particular side effect. 

Hunger and mental health

The mental effect on people using intermittent fasting for weight loss can be devastating, as can the metabolic consequences. Continually feeling hunger can result in a damaged relationship with food, binging and shame cycles and despair if you can't stick with it.

If you are continually trying to lose weight, and you try methods like this without making sustainable healthy eating changes, you will find that not only does your confidence in your ability to win start to dwindle, your body will start exhibiting signs of metabolic resistance - whereby any metabolic changes start becoming slower and slower, making it harder to lose weight in the future. 

Should YOU use intermittent fasting for weight loss and burning belly fat?

At the end of the day, using intermittent fasting as a strategy for weight loss and burning body fat can be really effective.

 As with any healthy eating change, the goal must be sustainability! Using intermittent fasting as an intense short term strategy can have consequences on metabolism and your body’s ability to cope with future fasting. Combining intermittent fasting with healthy eating habits and an exercise regime will enhance the benefits. 

It is an area where more research needs to happen so that we can understand the long term effects. I will keep you updated as new information comes to light!

Let me know  in the comments below your stories about intermittent fasting - has it been effective for you, are you just venturing cautiously into the realm, or are you a seasoned veteran?