The LeanWithLesley Guide to Intermittent Fasting

There are so many options and trends out there when it comes to healthy eating, so it’s understandable if you sometimes get confused about which nutrition approach will best suit you and your goals.

A healthy lifestyle should be all about balance, this is one of the key factors for reaching your goals. A healthy lifestyle should allow you to enjoy yourself — finding a way to reach your health and fitness goals without restricting yourself. Limiting or cutting certain foods that you love can be very hard to maintain.

With that in mind, today we’re talking about Intermittent Fasting, an approach to eating habits that has become increasingly popular. I am a big fan of Intermittent Fasting and as a result we have begun to use this method as an option on our online 4 Week Challenge and for our Private Clients.  Many LWL Members have been asking me about it , so we’ve provided some insight into this on trend method.

What is Intermittent Fasting?

Intermittent Fasting is an eating pattern (instead of an eating plan) that is broken into distinct periods of eating which are then followed by periods of fasting. Unlike a diet which dictates what kinds of foods you should eat, Intermittent Fasting only dictates when you should eat.

Depending on the type or method of Intermittent Fasting used the concept is to fast for a number of hours in the day and that fasting period varies, but will always exceed the eating window. At LeanWithLesley we recommend fasting for between 14 and 16 hours, allowing a "feeding" window of either 10 or 8 hours, 14/10 or 16/8. In the "fasting" period you do not eat or drink anything other than water, black coffee and black tea.  For me personally, I have my first meal around 12 noon and my last meal consumed by 8pm.  I aim to get 7 hours sleep each day, which alleviates my fasting period by the same amount of hours, but my body is still benefiting from the fasting period working it's magic!

Why has intermittent fasting gained popularity in recent times? It is believed that intermittent fasting may lead to a range of health benefits, including decreases in weight and disease risk.

So how does it work?

The three most common methods of the intermittent fasting diet are:

16:8 method (LWL Choice)

As I mentioned earlier it involves eating within an eight-hour window and to fast for the remaining 16 hours. For example, if you were following this method, you might choose to eat between 11am and 7pm and then fast for the remaining hours of the day. At first, if the 16 hour fasting period proves too challenging I recommend trying 14 hours fasting with a 10 hour eating window, so that you can explore the concept of Intermittent Fasting and if it suits you.

In this case, a majority of the fasting hours may be spent sleeping. It does NOT require you to count calories — simply eat as you normally would within what is known as the ‘eating window’.  However, as with all lifestyle choices it is important for your wellbeing that the type of food consumed is of nutritional benefit to your body. 

If you have a date night, or an event you have to go to that requires an evening meal, well then that's what you have to do.  This shouldn't be so restrictive that you cannot have a social life. You just get back on track the next day, sticking with the eating window and fasting period that you set in place from the outset.

5:2 method

This method involves eating as you normally would for five days of the week and eat one quarter (generally about 500 to 600 calories) of your daily calorie needs for the remaining two days of the week. For example, Monday to Friday you can eat as you normally would and on Saturday and Sunday you may choose to eat 500-600 calories per day. To ensure you don’t go over the suggested calorie count on fasting days, tracking calories may be necessary. 

Alternate day fasting

As the name suggests, this method involves alternating between days of eating as you would normally with days that consist of one meal that provides about 25% of your daily calorie needs. For example, you might choose to fast on Monday, Wednesday and Friday and eat as you normally would on other days.

Deciding whether a daily 16/8 (14/10) approach or something more like a weekly 5:2 method will work better for your schedule is very important. You need to consider when in the day do you usually feel hungry? What time do you usually get up and go to bed? When time in the day do you usually workout? Jot this information down, this will help you to schedule your plan. You should make IF work around you.  Take into consideration when you tend to go to sleep and wake up.  Ideally, we want to avoid feeling "hangry" and we need to maintain energy levels.

How does Intermittent Fasting affect your body?

Potential weight loss

All weight-loss diets have something in common — reducing calorie intake. While intermittent fasting is a pattern of eating rather than a diet, it still achieves the same result of reducing the amount of calories you eat over time. I'm not such a fan of the 5:2 method or the alternate fasting days, however I believe that the 16:8 is such a clever way to train our bodies to use all of the energy it consumes to burn fat and help to increase lean muscle.

The 16:8 style of Intermittent Fasting can without even realising, reduce your total calorie intake as it often leads to eating less than you normally would in a day. This is usually because you feel more full within the short period of time that you do eat and therefore you may end up eating 2 meals in the day rather than 3 and snacking less.

Intermittent Fasting is often associated with weight loss because it can help to lower insulin levels. Insulin is a hormone that has two main roles:

  • It helps your body turn sugars from food into energy.
  • It stores excess sugars as fat which can be used for fuel when needed (for example, between meals or when you are sleeping). 

When we eat, insulin levels are high as we draw energy from our food and store away any excess. Between meals, insulin levels drop and stored fat can be broken down to be used as energy.

Essentially, intermittent fasting has the potential to increase the time your body has to burn fat between meals and may therefore be used to help increase weight loss.

This isn’t the only way your body can burn fat though! If fat loss is your goal, research indicates what kicks this process off is how many calories you eat per day overall, not when and how often you eat.

So whether you choose to eat three larger meals within a shorter frame of time or five small meals spanned out evenly over the day, you can still lose fat if your calorie intake is less than your calories burned.

Risks associated with this

It might be easy to think that you can eat whatever you like during your “eating window” or that you can eat more to compensate for meals you’ve skipped. But unhealthy food choices may lead to nutrient deficiencies, lack of energy, or it can actually lead to weight gain if you end up eating more than you normally would. As a rule, it’s important to eat a range of nutritious whole foods, to ensure you’re feeling your best.  Following the LWL Food Plans with all our deliciously simple and healthy recipes will keep you on track.


It is believed that intermittent fasting may stimulate ‘autophagy’, a natural process in which the body gets rid of and recycles cells that have been damaged. Think of it as your body’s form of housekeeping. An accumulation of too many damaged cells can lead to disease and signs of ageing. 

Exercise triggers autophagy by putting your body under a mild form of stress. Stress is often seen as negative, but it can actually be positive in small amounts. It signals to your body to protect itself when there is a perceived danger and makes your cells more resilient in the long term.  It is believed that intermittent fasting may also trigger autophagy.

Your body senses a threat of possible starvation when you go for extended periods without food. Aside from drawing upon your back-up stores of energy (such as fat, YES!), the body’s immediate response is to remove and recycle any cells that may cause further danger to your body to increase your rate of survival. Intermittent fasting is intended as a way to trigger the autophagy process without actually experiencing any real danger.

How to achieve autophagy without Intermittent Fasting

If you want to experience the benefits of autophagy without having to do intermittent fasting, then consider including exercise in your daily routine if you haven’t already!

Exercise is another way of inducing small amounts of positive stress on the body and therefore promotes the natural process of autophagy.


Have you noticed that you get hungry at the same time every day? Some people don’t feel hungry at all in the morning while others might be famished!

Everyone experiences hunger at different times depending on their individual metabolism and how often they eat. If you eat breakfast at the same time every day and then one day you skip it, you are more likely going to feel really hungry! Your body gets used to whatever eating schedule you train it with.

Intermittent Fasting initially may leave you feeling hungry, tired and unable to concentrate when you remove a meal that your body has been used to receiving at a certain time. This initially leads to an increase in a hormone called Ghrelin, known as ‘the hunger hormone’. 

However, if that hunger is not fulfilled within about two hours, the hunger passes as Ghrelin decreases. You might have noticed that this wave of hunger has happened to you previously when you’ve had a busy day and haven’t had time to eat — you suddenly realise the feeling of hunger has come and gone. 

As long as you’ve eaten an adequate amount of food within the last 24 hours, your body should be able to use its energy stores in between meals to keep your brain and body functioning. However, if you’re already under a lot of stress, skipping that meal might not be so good. 

Why? Fasting stimulates Cortisol, the stress hormone, which can be beneficial in small amounts but harmful if you already suffer from high cortisol issues. In this specific case, intermittent fasting may not be for you. 

Remember, if you’re not feeling well on any kind of eating plan, you should stop immediately. There is always a plan to suit you, don't be disappointed or allow yourself to get deflated, as everyone is different and there is always a solution to a healthy eating pattern and daily exercise routine to get you the results you are looking for.

Intermittent Fasting Safety

Intermittent fasting is not a way of eating that suits everyone. In fact, if you have any of the below conditions, then intermittent fasting should be avoided:

  • Diabetes.
  • A history of disordered eating (particularly those involving self-restriction). 
  • Using medications that require food intake.
  • Experiencing an active growth stage, such as adolescence.
  • Pregnant or breastfeeding.
  • If you are underweight

If you have any questions just email me: lesley@leanwithlesley.com 

Intermittent Fasting and Exercise

If you are active and are considering Intermittent Fasting, keep in mind how your workout fits around your eating schedule. 

Some of us feel fine working out in a fasted state but others can feel flat, nauseated and light-headed when doing fasted cardio or any intense activity before having a meal. This is ultimately up to you to decide if intermittent fasting can be scheduled appropriately to work around your training.

Remember too that Intermittent Fasting will not be for everyone. If you are serious about doing IF in a healthy and mindful way, come up with a plan, perhaps together with me to guide you, set a time frame and at the end of that time frame, if it doesn't suit we can make sure you have a plan to help reintroduce a more regular eating schedule back into your life.