How often do you eat? If you’re like most fitness enthusiasts, you probably go beyond the three traditional meals and have five or even six small meals every day. And for years, this has been the prevailing wisdom. The driving force behind this approach is the idea that doing so will boost your metabolism and ward off the dreaded “starvation mode,” which all athletes struggle against. Many people who practice this sort of grazing also do so with the hope that they will be able to balance their blood sugar and avoid the midday crash that afflicts us all. A new approach to eating, however, promises to achieve all of that, plus more, while requiring you to do the exact oppose: Fast.
What is it?
Specifically, as the name Intermittent Fasting (or IF) suggests, the dieting method asks that you regularly go without eating. But there are several different approaches to IF that adjust both the frequency and duration of the fasts. Generally, intermittent fasting can be divided into two main categories: periodic fasts and daily fasts.
Although there are programs out there that offer specific fasting schedules, periodic fasts tend to be open to interpretation. These are usually 24-hour fasts that occur either once per year or even as often as once every week. It is recommended, however, that you don’t fast any more than one day each week.
The daily fast, despite its more intimidating name, is generally less severe since the actual duration of the fast is reduced. By limiting, your “feeding window” or amount of time that you allow yourself to eat during the day, you can prolong the natural fast that we all experience while sleeping. For example, the most popular programs require you to devote 16 hours to fasting, giving yourself an 8 hour eating window. This means that if your first meal is at 9am, your last meal of the day would by at 5pm. During that time you’re allowed to eat whenever you’d like, as long as you don’t exceed your normal caloric needs.
Why Fast?
But what are the benefits of fasting? And, if forcing your body into a severe caloric deficit can actually slow down your metabolism and cause muscle loss, why do it?
As with all health and fitness regimes, the proponents of IF tout a wide range of benefits, which include the ability to prevent type 2 diabetes, heart disease and obesity, as well as contribute to a longer lifespan. Counter-intuitively, Intermittent Fasting is also said to be able to contribute to muscle growth and a lean appearance.
But do these claims stand up to the test of clinical studies? In most cases, yes. But with a few expected caveats that will be discussed later.
Intermittent fasting does in fact help to improve insulin sensitivity, meaning that the hormone has a bigger impact on your body and elicits more of a response. A strong insulin response is key in maintaining balanced blood sugar levels and ensuring that the needed nutrients get to your muscles quickly. This improved use of insulin is responsible for the decreased risk of types 2 diabetes associated with intermittent fasting.
Studies have also confirmed that intermittent fasting causes the human body to target fat for fuel more aggressively than otherwise, which reduces both cholesterol and body fat. Of course, the trimmed look that comes from burning all that body fat is the most famous effect of intermittent fasting but there are many more important unseen, internal benefits.
Fasting also stimulates autophagy, your body’s way of clearing out potentially dangerous waste products, some of which have been linked with Alzheimer’s, Parkinson’s and other severe neurological diseases.
It is true that previous studies have suggested that a calorie-restricted diet can increase lifespan but these findings have since been called into question by newer research.
Cautions and Things to Know
Sure, intermittent fasting sounds like the solution to all sort of health problems and could even be just the thing to give you a boost towards your fitness goals. But, IF isn’t for everyone. People who have specific caloric and nutritional needs, especially pregnant women, should not picking up fasting. As a matter of fact, everyone should discuss the idea with their doctor before getting starting.
There’s a particular concern for people with heart conditions, as well. The effect isn’t full understood but some studies have shown that long-term fasting can cause a hardening of the heart’s tissue.
One of the largest concerns with IF is that the extreme hunger pangs make you gorge when you finally get to eat. Supporters say that while this is a difficult aspect of fasting, it will ultimately help you gain control over these cravings so that they don’t control you.
If you do decide to fast, you should start out with a daily fast, using the 16/8 model for men and 14/10 for women. This will help you start out slowly and build the self-control necessary for a full 24 hour fast.
Have you tried intermittent fasting? Please share your experience in the comments.
Sources
http://www.scientificamerican.com/article.cfm?id=how-intermittent-fasting-might-help-you-live-longer-healthier-life&page=2
http://www.sciencedaily.com/releases/2013/04/130426115456.htm
http://jap.physiology.org/content/99/6/2128.full
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