Intermittent Fasting for Weight Loss

Thinking of trying intermittent fasting to lose fat? Get the facts first.Touted as next “big” new diet, intermittent fasting has taken to the TV (Horizon) and social media sites of late - with many jumping on the bandwagon.

Unfortunately, as ever, plenty of people only read/take/use half the information with regards to intermittent fasting.

Firstly it’s not starvation, or just “skipping” a meal. It’s structured, or should be, in that you know when you are starting and finishing the fast, and what you’re going to be eating to break the fast.

It’s not, as was suggested on said TV programme, about eating what you want for a few days and then fasting for a couple. This is plain stupid and will damage internal health, and is more likely to cause you weight gain in the long run due to irregular blood sugar levels.

It’s also not about using fasting a few times a week to just cut back calories and get “skinny”. There are too many people with eating / psychological issues, and this is the one down side of IF and it’s “use”.

So what is Intermittent Fasting?

When we eat food, the majority is stored as something called glycogen, and is used for daily energy. This glycogen is stored in your muscles (for use when they move!) and your liver and brain.

When we are in a fasted state, our body will start to utilise fat stores for energy, alongside the glycogen in our liver.

The glycogen in our muscles is used up quicker through more intense training such as challenging weight sessions of intervals/sprints. (Another reason to include these in your training over long arduous runs/ cross trainer sessions.....but that’s another article!)

The benefits of short-term intermittent fasting include:

-    Decreased bodyfat and weight
-    Decreased blood glucose levels
-    Decreased insulin levels (your bodies ability to react and deal with carbohydrates)
-    Increased Insulin sensitivity
-    Increased Glucagon levels (fat burning hormone, in relation to insulin a fat storing hormone)

It’s advisable to drink water during a fasted period, some people will go further and still drink herbal/green tea, and black coffee

When breaking a fast, it’s often best to eat something nutrient rich, but light on the digestive system, so a fish salad with plenty of colours is a great choice.

Fasts can last anything from 15hours to 24 hours. This can include sleep time by the way!
 After around 15 hours your body has moved into a “fat burning mode”, moving fats from stored tissue, into the blood stream for use. There is a protein in our muscles called Uncoupling Protein-3 which is a strong player in the “fat burning” mode. Studies have shown this increases by 5 times after as little as 15 hours of fasting!


Intermittent Fasting for Weight Loss

A further study showed that after 24 hours of fasting the amount of fat being released and burnt by the body have been increased by over 50%.

We could go into a lot more on hormones and their play in intermittent fasting, but I’d seriously advise reading a book called Eat Stop Eat by Brad Pilon. It’s a short read, full of facts and studies and shows how it works!

I’ve used intermittent fasting myself and with clients. It can somertimes be a mental challenge when you get tummy rumbles,  but with a strong focus, and “keeping busy” you can easily move past this mental block.

Intermittent fasting ISN’T THE answer to fat loss, but I think when used in a controlled format it has it’s benefits.

Key tips:

-   Plan your meal before and after the fast. Just deciding to not eat for a few hours isn’t going to work.
-    Fasts should also be planned - know when it finishes, and know when you’re next one is
-    Don’t surround yourself with food, or be around people eating. It’s a mental challenge as much as a physical one. Think about it, you’ve PLENTY of stored bodyfat and glycogen, you will not stop functioning!
-    Start with some 17 hour fasts to start with, remember bed time is included, so if your last meal is 7pm, you can eat again at 11
-    You’ll find working out is ok in a fasted state. I often find I’m a lot more focussed, and workouts can be more intense. I’d say if you’re working out for more than an hour or an endurance style workout it’s best not to do in a fasted state. Equally if you suffer from diabetes or any medical condition, seek medical advice first.

As with any “diet” fasting isn’t the key or answer. But as part of a balanced plan of healthy living, exercise and eating it can have it’s benefits but physically and mentally.

Before you start do some research, read Eat Stop Eat and give it a try!


By Mark Raynsford

Mark Raynsford is a highly respected personal trainer based in Surrey, UK specialising in fat loss. If you'd like to train with Mark visit his website: Or for more of Mark's tips and advice take a look at his blog:



For more on intermittent fasting visit Fitness Rocks' founder Julia Buckley's blog where she's been sharing personal her experiences of trying it out: Julia's Fitness Blog

Tags: fasting for weight loss, intermittent fasting, intermittenting fast to lose weight, what is intermittent fasting