Intermittent fasting (IF) refers to eating patterns in which there is no calorie intake or severe calorie restriction for an extended period of time. There are many different subgroups of intermittent fasting, each with individual variation in fasting duration; some for hours, others for days. This has become an extremely popular topic in the scientific community due to all of the potential fitness and health benefits being discovered.
WHAT IS INTERMITTENT FASTING (IF)?
Fasting, or periods of voluntary abstinence from food, has been practiced around the world for centuries. Intermittent fasting with the aim of improving health is relatively new. Intermittent fasting involves restricting food intake for a set period of time and does not involve any changes to the actual foods you eat. Currently, the most common IF protocols are a daily 16-hour fast and a full day fast, one or two days per week. Intermittent fasting could be viewed as a natural eating pattern that humans are built to implement, and it can be traced back to our Paleolithic hunter-gatherer ancestors. The current model of a planned intermittent fasting program could potentially help improve many aspects of health, from body composition to longevity and aging. While IF goes against the norms of our culture and our daily routines, science may point to less frequent meals and more fasting as the optimal alternative to the normal breakfast, lunch, and dinner model. Here are two common myths related to intermittent fasting.
Myth 1 – You must eat 3 meals a day: This “rule”, common in Western society, was not developed based on evidence of improved health, but was adopted as a common pattern for settlers and eventually became the norm . Not only is there a lack of scientific justification for the 3-meals-a-day model, recent studies may show that fewer meals and more fasting are optimal for human health. A study has shown that one meal a day with the same amount of daily calories is better for weight loss and body composition than 3 meals a day. This finding is a fundamental concept extrapolated to intermittent fasting, and those who choose IF may find it best to eat just 1-2 meals a day.
Myth 2 – You need breakfast, it’s the most important meal of the day: Many false claims have been made about the absolute necessity of breakfast every day. The most common claims are “Breakfast increases metabolism” and “Breakfast decreases food intake later in the day”. These claims were disproved and studied over a 16-week period, with the results showing that skipping breakfast did not decrease metabolism and did not increase food intake at lunch and dinner. It’s still possible to do intermittent fasting protocols while still having breakfast, but some people find it easier to eat a late breakfast or skip it altogether, and don’t let this common myth get in the way.
TYPES OF INTERMITTENT FASTING:
Intermittent fasting comes in a variety of forms, and each can have a number of unique benefits. Each form of intermittent fasting has variations in the fasting-to-eating ratio. The benefits and effectiveness of these different protocols may vary individually and it is important to determine which one works best for you. Factors that may influence selection include health goals, daily schedule/routine, and current health status. The most common types of IF are alternate day fasting, time-restricted food intake, and modified fasting.
- ALTERNATIVE DAY FASTING:
This approach alternates days of no calories (from food or drink) with days of free feeding and eating whatever you want.
This plan has been shown to help with weight loss, improve blood cholesterol and triglyceride (fat) levels, and improve blood markers of inflammation.
The main disadvantage with this form of intermittent fasting is that it is the most difficult to stick to during the fasting days due to the reported hunger pangs.
- MODIFIED FASTING – 5:2 DIET
Modified fasting is a protocol with programmed fasting days, but the fasting days allow for some food intake. In general, 20-25% of normal calories may be consumed on fasting days; So if you normally eat 2000 calories on regular meal days, you are allowed to eat 400-500 calories on fasting days. The 5:2 portion of this diet refers to the ratio of non-fasting to fasting days. So on this regime, you would eat normally for 5 straight days and then fast for 2 straight days or limit your calorie intake to 20-25%.
This protocol is great for weight loss, body composition, and may also help regulate blood sugar, lipids, and inflammation. Studies have shown that the 5:2 protocol is effective for weight loss, improves/lowers inflammatory markers in the blood (3) and shows signs of improvement in insulin resistance. In animal studies, this modified fasting 5:2 diet resulted in less fat, less hunger hormone (leptin), and increased levels of a protein responsible for improving fat burning and blood sugar regulation (adiponectin).
The Modified 5:2 Fasting Protocol is easy to follow and has a small number of negative side effects, including hunger, low energy, and some irritability early in the program. In contrast, however, studies have also found improvements such as reduced tension, less anger, less fatigue, improvements in self-confidence and a more positive mood.
- TIME LIMITED FEEDING:
If you know someone who said they do intermittent fasting, chances are it’s a time-restricted diet. This is a type of intermittent fasting used daily, in which calories are taken in for only a small part of the day and fasted for the rest. Daily fasting intervals on time-restricted diets can range from 12 to 20 hours, with the most common method being 16/8 (fasting 16 hours, consuming 8 calories). For this protocol, the time of day is not important as long as you fast for a continuous period and only eat during your allowed period. For example, on a 16/8 time-limited eating program, one person may have their first meal at 7:00 a.m. and their last meal at 3:00 p.m. (from almost 3:00 p.m. to 7:00 a.m.) while another person have their first meal at 1 p.m. and their last meal at 9 p.m. (quickly from 9 p.m. to 1 p.m.). This protocol is meant to be done every day for long periods of time and is very flexible as long as you stay within the fasting/eating window(s).
Time restricted dieting is one of the easiest intermittent fasting methods to follow. Using this along with your daily work and sleep schedule can help achieve optimal metabolic function. Time-limited feeding is a great program for weight loss and body composition improvement, as well as some other general health benefits. The few human studies that have been conducted found significant weight reductions, reductions in fasting blood sugar, and improvements in cholesterol levels, with no change in perceived tension, depression, anger, fatigue, or confusion. Some other preliminary results from animal studies showed time-restricted feeding to protect against obesity, high insulin levels, fatty liver disease and inflammation.
The ease of use and promising results of time-restricted feeding could potentially make it an excellent option for weight loss and chronic disease prevention/treatment. When implementing this protocol, it may be good to start with a lower fasting-to-eating ratio like 12/12 hours and eventually work your way up to 16/8 hours.
FREQUENT QUESTION ABOUT INTERMITTENT FASTING:
Can I eat or drink anything during intermittent fasting? Unless you are on the modified 5:2 fasting diet mentioned above, you should not eat or drink anything that contains calories. Water, black coffee, and any food/drink that does not contain calories can be consumed during a fast. In fact, adequate water intake is essential during IF, and some say drinking black coffee while fasting helps reduce hunger.
IF YOU ONLY WANT THE BENEFITS:
Research on intermittent fasting is still in its infancy, but it still has tremendous potential for weight loss and treating some chronic diseases.
To recap, here are the potential benefits of intermittent fasting:
Shown in Human Studies:
- Weight Loss
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Improve blood lipid markers like cholesterol
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Reduce Inflammation
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Reduced stress and improved self-confidence
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Improved mood
Shown in animal experiments:
- Less body fat
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Decreased levels of the hunger hormone leptin
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Improve insulin levels
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Protect against obesity, fatty liver disease and inflammation
5. Longevity
Thanks to Blake Pennock
