A Beginners Guide to Intermittent Fasting

If leanness in combination with increased strength gains is something that sounds appealing to you, then consider intermittent fasting (IF). This is an alternative approach that you can use instead of the conventional 5 or 6 small meals per day that most people tend to recommend. Not only can you skip breakfast, but your body will not start to cannibalize its own muscle and you won’t go into starvation mode.  The questions are how and why does IF work and can it really be of any benefit to you? Before we move on with answering these questions; let’s be clear from the outset that intermittent fasting is not a diet strategy such as Zone or Paleo.

However, it can be experimented with and used in conjunction with your current diet plan. The fasting process should enhance the diet plan that you are following and you don’t even have to restrict your calories or macros.  Intermittent fasting is in fact an ‘eating pattern’ that organizes your meals; so that you can get the most out of them.  It is not rocket science and in basic terms intermittent fasting is ‘the break in time from eating your last food intake until you eat your next meal’. Here is an infographic outlining IF before we get into details:

Practical Benefits When Using the Intermittent Fasting Model

  • IF is easy to follow, you don’t need to prepare breakfast, just drink a glass of water and off you go

  • By skipping meals you are saving money and time in the kitchen preparing food

  • Once you get over the fact that you have to eat all of your calories within your eating window the training benefits will start to appear fairly rapidly.

The Fast

A ‘fast’ can be interrupted by sleep or by the designated time of your eating window. A very simple example of an IF is the 12/12 model where you eat dinner at 7 pm and fast or sleep until 7 am breakfast time. This 12/12 fast maybe the ‘norm’ for some people as it mirrors their sleep and eating patterns. One of the additional bonuses of IF is that it can be adjusted to suit your needs in terms of lifestyle in and out of the gym. Therefore, subconsciously you may already be following an intermittent fasting routine and fasting for 16, 18 or even 24 hours. So that begs the questions, where does the energy actually come from when you are fasting then? In a fasted state the body is no longer absorbing nutrients from your last meal but is dependent on three sources - the glycogen stores within the muscle and liver, body fat which is broken down into free fatty acids and glycerol which is converted to energy.

However, the liver glycogen will run out after about 16 hours (this depends on your BMR, age, activity levels, fitness levels etc) and the body will look to break down the muscle protein for energy. The body will look to utilize the proteins in the blood before breaking down the muscle tissue and that is why eating slow burning proteins in your eating window will prevent this from happening. It will ensure there that is enough free amino acids in the blood for the conversion of glucose and this will prevent the muscle from cannibalizing itself.  In addition, it should give you more than enough energy to train with some real hammer during your fast.  Many strength athletes tend to train towards the end of their 16 hour fasting window and then post exercise the muscle is like a sponge waiting to refuel on any amino acids, nutrients, hormones and carbs.  This mechanism is a key part of the muscle building and strength gains process.

The Role of Insulin

What fasting does to the body is relatively simple but many fitness writers tend to make it a more complex subject than it actually is. Most people are aware of the role of insulin in building muscle mass and how too much insulin caused by a spike in blood glucose can cause the body to store fat. During this fasting state it is much easier to burn fat because the insulin levels are low. You should fast more than 12 hours because only then is our body really in a fasted state and this helps to burn the inaccessible body fat. This is rarely seen in normal eating schedules, many individuals lose weight; without reducing calories, the amount of food consumed or the impact of exercise. Research has also shown that intermittent fasting enhances the effectiveness of insulin to store glucose and is used to breakdown fats, this mechanism is called ‘insulin sensitivity’. However, in the presence of insulin the human growth hormone (HGH) response is muted and in simple terms ‘fasting’ can majorly boost this muscle building hormone. Research has indicated that if you fast for too long i.e. 28 hours or more, your HGH levels will be reduced and you will lose some of its major muscle building benefits. HGH preserves lean body mass and this is essential for keeping the body’s metabolism high. Lean mass has a higher energy requirement than fat mass. HGH also aids in the release of stored fat for energy and enhances cellular repair. Increased HGH level delays the onset of cortisol; which is a hormone used in the storage of belly fat. Are we starting to see the bigger picture yet?

Possibly the ‘Best’ Intermittent

Fasting Strategy for Athletic Performance

Going too deep into the details of each of the numerous IF models is beyond the scope of this article e.g. weekly fasting, alternative day, random meal skipping, eat stop eat and the warrior diet will not be discussed.  However, the best IF approach to use for strength gains and athletic performance will be discussed in great depth and one of the major benefits of IF is that it can be tweaked to match your individual needs.

The 16/8 Leangrains model

It incorporates a 16 hour fast combined with an 8 hour eating period. It doesn’t matter when you begin your 8 hour eating period e.g. you can start at 9am and finish at 5 pm or start at 1pm and finish at 9 pm. You can skip breakfast and eat lunch, do whatever works for you, as long as you abide by the 16 hour fast protocol. Due to the fact that the 16/8 model is undertaken every day, it should get you into good eating habits quite rapidly as many people eat when the clock tells them and not when they feel hungry. This system is about controlling the times that you can’t eat in relation to when you can. This is a great protocol for getting control of your appetite and eating within the right time frame which can help you to lose weight and build strength.

Some Practical Advice

This is some practical advice to use when following the 16/8 fasting model; so that you are full of energy when you are training during your fast. This will ensure that you are training to your maximal potential after your fasting period and it will enhance any strength and performance gains in the gym. The key nutritional guideline to follow is to eat lots of protein and more carbs/calories on your training days. On rest days try to consume more healthy fat and less calories. Knowing your own macros is important but is beyond the scope of this article. In addition, break your fast 30 minutes before you work out with 10g of branched chain amino acids (BCAAs). The BCAAs are there to protect your muscle pre and post work out, and the protein will spike your insulin levels slowly and your human growth hormone levels will not be blunted. After you have finished working out eat an energy dense meal of about 50% of your daily calorie intake. This is the best time to consume some complete proteins and some clean carbs to aid recovery and to replenish your glycogen stores ready for the next day’s work out. Lastly, listen to your body as there are no hard and fast rules for intermittent fasting. If you are hungry and/or feel weak when training then you need to eat more of the right calories and maybe adjust your eating window. It will take some time for your body to adjust to fasting but once you are in the groove you will be surprised at your strength gains and fat loss. So why not give IF a try and see what happens!

Nicole Clark

Nicole Clark is a U.S. trained and licensed physiotherapist who became interested in physiotherapy through her experience as a competitive swimmer and runner. Nicole earned her Master of Science in Physiotherapy from Springfield College in 2003, graduating with honors. Her thesis was accepted to the Combined Sections Meeting of the American Physical Therapy Association in 2004. Nicole has sought post-graduate clinical education in such topics as trigger point dry needling, advanced treatment of the foot and ankle, orthotic fitting, corrective exercise, and joint mobilization.

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