Intermittent fasting is a new trend in the world of health and fitness. Whilst many diets focus on what to eat, intermittent fasting is all about when you eat and cycles between periods of fasting and eating. In this respect, it’s not a diet in the conventional sense but more accurately described as an eating pattern. Studies have shown that it can have powerful effects on your body and brain and many people are using it to lose weight, improve their health, and simplify their lifestyle.
Neuroscientist Mark Mattson, Ph.D. has studied intermittent fasting for 25 years. He claims that evolution has made our bodies capable of going without food for many hours, sometimes for days or even longer. In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive — and thrive — for long periods without eating. It is believed that, in fact, fasting from time to time is more natural than always eating 3–4 (or more) meals per day.
If we went back 50 years, we would see that it was easier to maintain a healthy weight back then. Dietitian Christie Williams, M.S., R.D.N., explains:
“There were no computers, and TV shows turned off at 11 p.m.; people stopped eating because they went to bed. Portions were much smaller. More people worked and played outside and, in general, got more exercise.”
Nowadays, TV, the internet, and other forms of entertainment are available 24/7. We stay awake for longer hours to catch our favorite shows, play games and chat online. We’re sitting and snacking all day — and most of the night.”
Extra calories and less activity can mean a higher risk of illnesses, such as obesity, type 2 diabetes and heart diseases. Scientific studies show that intermittent fasting may help reverse these trends and minimise the risk for such illnesses.
There are several different ways to practise intermittent fasting, but the main principle is based on choosing regular time periods to eat and fast. It involves splitting the day or week into eating and fasting periods. For example, you might try eating only during an eight-hour period each day and fast for the remainder. Or you might choose to eat only one meal a day two days a week.
During the fasting periods, you eat either very little or nothing at all. Mattson says that when the body is deprived of food for several hours it exhausts its sugar stores and starts burning fat. He refers to this as metabolic switching.
“Intermittent fasting contrasts with the normal eating pattern for most people, who eat throughout their waking hours,” Mattson says. “If someone is eating three meals a day, plus snacks, and they’re not exercising, then every time they eat, they’re running on those calories and not burning their fat stores.”
Intermittent fasting works by prolonging the period when your body has burned through the calories consumed during your last meal and begins burning fat. By reducing your calorie intake, all of these methods should cause weight loss as long as you don’t compensate by eating much more during the eating periods. It’s important to check with your doctor before starting intermittent fasting. Once you get his or her go-ahead, the actual practice is simple.
These are the most popular methods:
- The 16/8 method: This is the most popular, and also the simplest, most sustainable and easiest method to stick to. When practising intermittent fasting through this daily approach, you restrict eating to one six- to eight-hour period each day. You may choose eating for eight hours and fasting for 16.
- Eat-Stop-Eat: This involves fasting for 24 hours, once or twice a week, for example by not eating from dinner one day until dinner the next day. lly .Longer periods without food, such as 24, 36, 48 and 72-hour fasting periods, are not necessarily better for you and may be dangerous. Going too long without eating might actually encourage your body to start storing fat instead as a response to starvation.
- The 5:2 diet: With this method, you consume only 500–600 calories on two non-consecutive days of the week, but eat normally the other 5 days. An example would be if you chose to eat normally on every day of the week except Mondays and Thursdays, which would be your one-meal days.
Mattson found in his research that it can take two to four weeks for the body to become accustomed to intermittent fasting. In fact, you might experience hunger or mood swings when trying to get used to the new routine. However, he observes, research subjects who make it through the adjustment period tend to stick with the plan, because they notice they feel better.
What can I eat while intermittent fasting?
During the fasting periods there are certain beverages that are permitted to help alleviate the feeling of hunger, which include water , black coffee and tea. During the eating periods, it is recommended to keep in mind a healthy diet and not overcompensate. You’re not likely to lose weight or get healthier if you pack your feeding times with high-calorie junk food, super-sized fried items and treats.
Williams says that what she likes most about intermittent fasting is that it allows for a range of different foods to be eaten and enjoyed.
“We want people to be mindful and take pleasure in eating good, nutritious food,” she says. and supports good health.
Williams, like most nutrition experts, regards the Mediterranean diet as a good blueprint of what to eat, whether you’re trying intermittent fasting or not. You can hardly go wrong when you pick complex, unrefined carbohydrates such as whole grains, leafy greens, healthy fats and lean protein.
How It Affects Your Cells and Hormones
Studies have shown that when you fast, several things happen in your body on a cellular and molecular level. For instance, your body starts to adjust hormone levels to make stored body fat more accessible. On the other hand, your cells initiate important repair processes and change the expression of genes.
Here are some changes that occur in your body when you fast:
- Human Growth Hormone (HGH): The levels of growth hormone skyrocket, increasing as much as 5-fold. This has benefits for fat loss and muscle gain, to name a few.
- Insulin: Insulin sensitivity improves and levels of insulin drop dramatically. Lower insulin levels make stored body fat more accessible.
- Cellular repair: When fasted, your cells initiate cellular repair processes. This includes autophagy, where cells digest and remove old and dysfunctional proteins that build up inside cells.
- Gene expression: There are changes in the function of genes related to longevity and protection against disease.
A Very Powerful Weight Loss Tool
Weight loss is the most common reason for people to try intermittent fasting. Eating fewer meals leads to an automatic reduction in your calorie intake. Additionally, intermittent fasting changes hormone levels to facilitate weight loss by increasing the release of the fat burning hormone norepinephrine (noradrenaline).
Studies show that intermittent fasting can be a very powerful weight loss tool. These changes in hormones through short-term fasting may increase your metabolic rate by 3.6–14%. A 2014 review study found that this eating pattern can cause 3–8% weight loss over 3–24 weeks, which is a significant amount, compared to most weight loss studies .
According to the same study, people also lost 4–7% of their waist circumference, indicating a significant loss of harmful belly fat that builds up around your organs and causes disease
Another study showed that intermittent fasting causes less muscle loss than the more standard method of continuous calorie restriction.
Research shows that the intermittent fasting periods do more than burn fat. Mattson explains:
“When changes occur with this metabolic switch, it affects the body and brain.”
One of Mattson’s studies published in the New England Journal of Medicine revealed data about a range of health benefits associated with the practice. These include a longer life, a leaner body and a sharper mind.
“Many things happen during intermittent fasting that can protect organs against chronic diseases like type 2 diabetes, heart disease, age-related neurodegenerative disorders, even inflammatory bowel disease and many cancers,” he says.
Here are some intermittent fasting benefits research has revealed so far:
- Thinking and memory. Studies discovered that intermittent fasting boosts working memory in animals and verbal memory in adult humans.
- Heart health. Intermittent fasting improved blood pressure and resting heart rates as well as other heart-related measurements.
- Physical performance. Young men who fasted for 16 hours showed fat loss while maintaining muscle mass. Mice who were fed on alternate days showed better endurance in running.
- Diabetes and obesity. In animal studies, intermittent fasting prevented obesity. And in six brief studies, obese adult humans lost weight through intermittent fasting.
- Tissue health. In animals, intermittent fasting reduced tissue damage in surgery and improved results.
It is important to note that research is still in its early stages and many of the studies were small, short-term or conducted in animals. Many questions have yet to be answered in higher quality human studies.
Who Should Be Careful Or Avoid It?
It is necessary to understand that Intermittent fasting is certainly not for everyone and each individual should do what works best for them.
If you’re underweight or have a history of eating disorders, you should not fast without consulting with a health professional first as it can be downright harmful.
There is some evidence that intermittent fasting may not be as beneficial for women as it is for men. One study showed that it improved insulin sensitivity in men, but worsened blood sugar control in women.
Though human studies on this topic are unavailable, studies in rats have found that intermittent fasting can make female rats emaciated, masculinized, infertile and cause them to miss cycles.
There are a number of anecdotal reports of women whose menstrual period stopped when they started doing IF and went back to normal when they resumed their previous eating pattern. For these reasons, women should be careful with intermittent fasting. They should follow separate guidelines, like easing into the practice and stopping immediately if they have any problems like amenorrhea (absence of menstruation).
If you have issues with fertility and/or are trying to conceive, consider holding off on intermittent fasting for now. This eating pattern is likely also a bad idea if you’re pregnant or breastfeeding.
Safety and Side Effects
Hunger is the main side effect of intermittent fasting. You may also feel weak and your brain may not perform as well as you’re used to.This may only be temporary, as it can take some time for your body to adapt to the new meal schedule. Some people try intermittent fasting for weight management, and others use the method to address chronic conditions, such as irritable bowel syndrome, high cholesterol or arthritis.
Williams stresses that before you try intermittent fasting (or any diet), you should check in with your primary care practitioner first. Some people should steer clear of trying intermittent fasting:
- Children and teens under age 18.
- Women who are pregnant or breastfeeding.
- People with diabetes or blood sugar problems.
- Those with a history of eating disorders.
But, Williams says, people not in these categories who can do intermittent fasting safely can continue the regimen indefinitely.
“It can be a lifestyle change,” she says, “and one with benefits.”
Keep in mind that intermittent fasting may have different effects on different people. Talk to your doctor if you start experiencing unusual anxiety, headaches, nausea or other symptoms after you start intermittent fasting.
This is particularly important if you:
- Have diabetes
- Have problems with blood sugar regulation
- Have low blood pressure
- Take medications
- Are underweight
- Have a history of eating disorders
- Are a woman who is trying to conceive
- Are a woman with a history of amenorrhea
- Are pregnant or breastfeeding
All that being said, intermittent fasting has an outstanding safety profile. There is nothing dangerous about not eating for a while if you’re healthy and well-nourished overall.
Eating healthy is simple, but it can be incredibly hard to maintain. One of the main obstacles is all the work required to plan for and cook healthy meals.Intermittent fasting can make things easier, as you don’t need to plan, cook or clean up after as many meals as before. For this reason, intermittent fasting is very popular among the life-hacking crowd, as it improves your health while simplifying your life at the same time.
Intermittent fasting is not something that anyone needs to do and just like any other lifestyle change requires a lot of research. It is also recommended to follow the advice of health professionals. It’s simply one of many lifestyle strategies that can improve your health. Eating real food, exercising and taking care of your sleep are still the most important factors to focus on.
If you don’t like the idea of fasting, then you can safely ignore this article and continue to do what works for you. At the end of the day, there is no one-size-fits-all solution when it comes to nutrition. The best diet for you is the one you can stick to in the long run.
If you feel good when fasting and find it to be a sustainable way of eating, it can be a very powerful tool to lose weight and improve your health.