Intermittent fasting (IF) refers to dietary eating patterns that involve not eating or severely restricting calories for an extended period of time. There are many different subgroups of intermittent fasting, each with individual variation in the length of the fast; some for hours, others for day(s). This has become an extremely popular topic in the scientific community due to all the potential health and fitness 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 for the purpose of improving health is relatively new. Intermittent fasting involves restricting your food intake for a set period of time and does not include any changes to the actual food you are eating. 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 considered a natural eating pattern that humans are designed to implement and dates 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. Although IF goes against the norms of our culture and common daily routine, science may be pointing to less meal frequency and longer 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 should eat 3 meals a day – This “rule” that is common in Western society was not developed based on evidence of better health, but rather was adopted as the common pattern for colonists and eventually became the rule. Not only is there a lack of scientific foundation in the 3 meals a day model, but recent studies may be showing that fewer meals and more fasts are optimal for human health. One study showed that one meal a day with the same number of daily calories is better for weight loss and body composition than 3 meals a day. This finding is a basic concept that carries over to intermittent fasting and those who choose to do IF may find it better to eat just 1-2 meals per 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 a daily breakfast. The most common claims are “breakfast increases metabolism” and “breakfast decreases food intake later in the day.” These claims have been refuted and studied over a 16-week period with 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 without skipping breakfast, but some people find it easier to eat late or skip breakfast altogether, and this common myth shouldn’t get in the way.
TYPES OF INTERMITTENT FASTING:
Intermittent fasting comes in various forms, each of which can have a specific set of unique benefits. Each form of intermittent fasting has variations in the relationship between fasting and eating. The benefits and effectiveness of these different protocols may differ on an individual basis and it is important to determine which one is best for you. Factors that may influence which one to choose include health goals, daily schedule/routine, and current health status. The most common types of IF are alternate-day fasting, time-restricted feeding, and modified fasting.
1. FASTING ON ALTERNATE DAYS:
This approach involves alternating days with no calories (from food or drinks) with days of free eating and eating whatever you want.
This plan has been shown to help with weight loss, improve cholesterol and triglyceride (fat) levels in the blood, and improve markers of inflammation in the blood.
The main disadvantage of this form of intermittent fasting is that it is the most difficult to follow due to reported hunger during fasting days.
2. MODIFIED FASTING – 5:2 DIET
Modified fasting is a protocol with scheduled fast days, but fast days allow for some food intake. In general, 20-25% of normal calories are allowed on fast days; therefore, if you normally consume 2,000 calories on regular eating days, you will be allowed 400-500 calories on fasting days. The 5:2 portion of this diet refers to the ratio of non-fasting days to fasting days. So on this regimen I would eat normally for 5 days in a row, then fast or restrict calories to 20-25% for 2 days in a row.
This protocol is great for weight loss, body composition, and can also benefit blood sugar regulation, lipids, and inflammation. Studies have shown the 5:2 protocol to be effective in losing weight, improving/decreasing markers of inflammation in the blood (3), and showing signs of improving trends in insulin resistance. In animal studies, this modified 5:2 fasting diet resulted in increased fat, increased hunger hormones (leptin), and increased levels of a protein responsible for enhancing fat burning and metabolism. regulation of blood sugar (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 when starting the program. Contrary to this, however, studies have also noted improvements such as reduced tension, less anger, less fatigue, improved self-confidence, and a more positive mood.
3. FOOD WITH TIME RESTRICTION:
If you know someone who has said they’re doing intermittent fasting, chances are it’s in the form of time-restricted eating. This is a type of intermittent fasting that is used daily and involves only consuming calories for a small part of the day and fasting the rest. Daily fasting intervals in time-restricted eating can range from 12 to 20 hours, with the most common method being 16/8 (fasting for 16 hours, consuming calories for 8). For this protocol, the time of day is not important as long as you are fasting for a consecutive period of time and only eat in the time period allowed. For example, in a time-restricted 16/8 feeding schedule, one person may eat their first meal at 7 a.m. and last meal at 3 p.m. (fasting from 3 p.m. to 7 a.m.), while another person you can eat your first meal at 1 p.m. (fasting from 9PM-1PM). This protocol is meant to be done every day for long periods of time and is very flexible as long as you stay within your fasting/eating windows.
Time-restricted eating is one of the easiest intermittent fasting methods to follow. Using this in conjunction with your daily work and sleep schedule can help achieve optimal metabolic function. Time-restricted eating is a great program to follow for weight loss and improved body composition, as well as other general health benefits. The few human trials that have been conducted noted significant reductions in weight, reductions in fasting blood glucose, and improvements in cholesterol without changes in perceived tension, depression, anger, fatigue, or confusion. Some other preliminary results from animal studies showed that time-restricted feeding protects against obesity, high insulin levels, fatty liver disease, and inflammation.
The easy application and promising results of time-restricted feeding could make it an excellent option for weight loss and chronic disease prevention/management. When implementing this protocol, it may be good to start with a lower ratio of fasting to feeding, such as 12/12 hours, and eventually work your way up to 16/8 hours.
COMMON QUESTION ABOUT INTERMITTENT FASTING:
Are there any foods or drinks that I can consume during intermittent fasting? Unless you are following the 5:2 modified 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 fasting period. In fact, adequate water intake is essential during FI, and some say that drinking black coffee on an empty stomach helps decrease hunger.
IF YOU ONLY WANT THE BENEFITS:
Research on intermittent fasting is in its infancy, but it still has great potential for weight loss and the treatment of some chronic diseases.
In summary, these are the possible benefits of intermittent fasting:
Shown in Human Studies:
1. Weight loss
2. Improve blood lipid markers such as cholesterol
3. Reduce inflammation
4. Stress reduction and improved self-confidence
5. Improved mood
Shown in Animal Studies:
1. Decrease in body fat
2. Decreased levels of the hunger hormone leptin
3. Improve insulin levels
4. Protects Against Obesity, Fatty Liver Disease, and Inflammation