The concept of Intermittent Fasting[/b] (IF) is nothing new. It has been practiced in one way or form by our ancestors across the millennia. Our bodies evolved in the ‘hunter-gatherer’ era, when food wasn’t in abundance and meals weren’t so regular or evenly spread. As such, we’ve evolved with livers and muscles that store quickly accessible energy in the form of glycogen and our bodies hold long-lasting energy reserves in the form of fat that can sustain us for weeks when food is not available.
In the last century, our minds were polluted by the habit of eating three meals a day, with continuous snacking from morning to night. In recent years, IF has been gaining popular attention and scientific endorsement. The most popular being the 5:2 diet, which advocates eating without restrictions for five days and then consuming just 500 calories (600 for men) on each of the other two days of the week.
Another form of IF is time-restricted eating (TRE). ‘When’ you eat turns out to be just as important as ‘what’ you eat. We now know that there are a number of positive health implications in eating the same type and amount of food over a time restricted protocol versus ad lib eating. This even holds true when the foods are highly calorific. Of course, that’s not to say what you eat isn’t important. The aim is to still make the majority of your diet whole food, consisting of quality protein, healthy fats and plenty of vegetables. TRE is different from other diets in that we are not calorie or food restricting. In fact, TRE is more a shift in eating patterns rather than a diet.
Further research is needed to determine the ideal ‘feeding-fasting’ schedule. We are still unsure whether the daily start time or length of a fast is significant. The evidence so far seems to suggest a 14-16 hour fasting window, with some people obtaining better results restricting to just 6 hours feeding.
We’ve learnt that the complexity of the human body is such that it prefers to perform like clockwork. When the body spends less time and energy with the task of digestion, it leaves more capacity to focus on other beneficial activities – repair and maintenance. The short term detoxifying liquid diets that some people undertake actually have some merit in that they allow the body to focus on the process of daily repair, which can be beneficial for optimal cleansing.
Spreading calorie intake through the day perturbs metabolic pathways governed by circadian clock and nutrient sensors. In essence, the body stores fat whilst eating and during fasting, cuts down fat storage, shuts down glucose production and turns on fat burning mechanisms. Leptin (the hormone that regulates fat storage and hunger signals) and ghrelin (a hormone that tells your brain the body is hungry) are also normalized by fasting. Fasting lowers insulin and another hormone called insulin-like growth factor (IGF-1), which is linked to cancer and diabetes. Lowering these hormones may slow cell growth and development, which in turn helps slow the aging process and reduces risk factors for disease.
Glycogen is the body’s primary fuel source. It generally takes up to eight hours for the body to burn through these stores, following which the body will then turn to fat cells. Even eating your regular three meals a day makes it difficult for the body to burn fat.
Despite the common notion ‘breakfast is the most important meal of the day,’ some people find skipping breakfast fits nicely into their TRE regimen. As with all these regimens, one size does not fit all. The addition of a black coffee with full fat cream or coconut oil can help those people struggling with unwanted hunger cravings and keep them satisfied until lunch time.
You might be questioning whether TRE fits with your training regime. Fasting has been shown to have a beneficial effect in trained individuals because of the increased production of human growth hormone (HGH). One cautionary note, if you work out in the morning then making sure you eat a high quality protein-heavy meal soon after and skipping a meal later in the day would be more advisable. That being said, fasting is a source of stress and influences hormones like cortisol and adrenaline, therefore skipping a meal could potentially be detrimental in some individuals undertaking regular, intense physical training. People with already compromised cortisol and adrenaline levels may find that TRE tips them over the edge, with women being far more sensitive to unwanted side effects of fatigue, anxiety or irregular periods. The important message here is to listen to your body and adapt accordingly. The switch to TRE may not be a smooth transition for some people and can take a couple of weeks to adapt. With discipline and perseverance you may just yield the result you’ve long been yearning for.