Every major religion, from Christianity and Judaism, to Islam and Buddhism, practises a kind of fasting. Some in pursuit of purification, others in an attempt to move closer to God. The word ‘breakfast’ means to literally break a period of fasting.
Assuming, that is, you sleep for at least eight hours a night. It’s after this length of time that your body is said to be out of its digestive state, and into a fasting state.
Proponents of the many fasting diets that exist point to health benefits like fat loss, improved cognitive function and life extension – although this hasn’t been proven.
A hibernating bear will gorge itself on high-calorie foods before going to sleep, after which time it will lose up to 40% of its body mass. Some of it muscle, but most of it fat. This kind of natural adaptation by the body to the complete extended restriction of food, fasters say, is proof that fasting is not only viable, but essential every now and then.
Paracelsus, the 15th century physician who also happened to be a botanist and astrologer, said, “Fasting is the greatest remedy – the physician within.” A sentiment echoed almost 2,000 years earlier by Plato, Hippocrates and Aristotle.
As a modern way of eating, though, does fasting work? Can you train effectively on a fasting diet?
There are different kinds of fasting diets, which tend to split your daily meals differently. All of them require a significant reduction in calories. Some ask you to take on a liquid diet for a few days a week, while others encourage you to put 12 hours between two small meals.
Fasting is a state your body enters. When you’re eating, you’re not fasting, and when you’re digesting food, you’re not fasting. To be in a fasting state, you need to have digested your last meal completely. You need to have an empty stomach. That’s why breakfast is called breakfast.
People who don’t eat breakfast – intentionally or not – are in a minor fasting state until they eat lunch. If your goal is weight loss, then fasting this way usually doesn’t work. Not necessarily because your metabolism has slowed down, but because when it does come time to eat, you tend to eat more, or eat less, and snack on useless sugary carbohydrates in the afternoon.
To be brutally honest, there isn’t a lot of scientific evidence to back up claims that fasting does all of the things its proponents claim. Fast for long enough, though, and it’s likely that you will see some weight loss. There are two reasons why this happens:
Just like a ketogenic diet forces your body to call on fat stores for energy instead of carbohydrates, fasting forces your body to burn fat, in the absence of glucose from food.
The second reason is obvious. When you fast, you eat fewer calories. When you consume less calories than you use, you lose weight. A typical fasting day calorie guide is around 500 for women and 600 for men. That’s less than a third of the recommended daily calories for a healthy, active adult.
There are all sorts of extreme fasting diets, including water fasts and whole days without food. Neither of those will be beneficial to you if you’re not doing any sort of training. The ones you might be interested in involve intermittent fasting, where you eat fewer calories, with several hours between meals.
Whether you believe in liquid detoxing is up to you. Taking in your fasting day calories with a shake or smoothie is fine, providing you have an adequate mixture of vitamins and minerals.
A liquid protein fast might be preferable for training purposes, since protein is more filling than just juices and greens.
With a water fast, there are days when all you put into your body is water. Maybe a squeeze of lemon. Great if you want to lose weight, not so great if you want to perform physically. Some water fasters swear by the occasional complete restriction of food, reporting improvements in cognitive function in the long term.
By far the most widely-accepted and popular form of fasting – mostly likely because it involves the least amount of actual fasting.
5:2 refers to the days of week. On five out of the seven days, you eat a normal amount of calories (around 2,000-3,000 for low activity people.) You get to choose which two days out of the week are you fasting days, and on those days, you’re allowed up to 600 calories, split into two meals, 12 hours apart.
This intermittent fasting method involves fasting for 24 hours, once or twice a week (e.g. not eating from dinner, until dinner the following day).
Another popular intermittent fasting method, this involves restricting your daily eating period to 8 hours, then fasting for 16 hours in between. For example, you may eat between 12pm and 8pm and then not eat again until 12pm the following day.
It’s worth mentioning that most of the health benefits associated with fasting are anecdotal, despite its history. Reputable scientific studies on fasting are scarce, and any claims that it extends lifespans need to be taken with a pinch of salt.
Studies on fasting are usually carried out with rats, mice and monkeys. It’s difficult to prove that fasting will help you to live longer.
Some of the reported health benefits of fasting include:
Taking the above into consideration, it’s possible that intermittent fasting could have some positive effects on your training. Again, studies on the effectiveness of fasting on athletic performance are few and far between, but for some, the probable fat loss and the idea of a ‘warrior diet’ is enough to tempt them into fasting.
The warrior diet is based on the idea that our ancestors may have eaten just one meal a day. There’s little evidence to suggest this.
If indeed, intermittent fasting does contribute to a decrease in insulin production and an increase in growth hormone, then it could be beneficial to strength athletes.
A summary:
My advice is to try intermittent fasting for 30 days. See whether your performance improves, and note how you feel mentally throughout the month. If it works, great, if it doesn’t, fasting may not be for you.
Have you already tried fasting? Did it work well for you?
Despite the benefits we’ve learned about protein powders, not all of them are keto-friendly. Just like any product for people on a low-carb diet, you need to read the label closely to make sure you’re not consuming added carbs and sugars.
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Scott Reid
Author
Scott Reid is a 2 x Britain’s Strongest Man U105kg winner (2007 & 2008) and IFSA World's Strongest Man U105kg Competitor. He is an expert in strength and conditioning and also coaches functional nutrition. Scott’s passion for understanding the human body and how to optimise every aspect of it has driven him to study under legends such as Paul Chek. Scott now coaches MMA Athletes, Strongmen and Bodybuilders to name but a few, helping them to implement a well structured diet and become more powerful, explosive versions of themselves.