Intermittent fasting is an eating plan that alternates between fasting and eating on a fixed schedule. Research shows that intermittent fasting is a way to control your weight and prevent (or even reverse) some types of disease. But how do you do that? And is it safe?
What is intermittent fasting?
Many diets focus on...Whatfood, but intermittent fasting passeswhenyou are eating.
With intermittent fasting you only eat for a certain period of time. Research shows that fasting for a certain number of hours per day or eating just one meal a few days per week can have health benefits.
Johns Hopkins neuroforskerMark Mattsonhas been studying intermittent fasting for 25 years. He says that our bodies have evolved to be able to survive without food for many hours, or even several days or longer. In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive – and thrive – for long periods of time without eating. They had to: It took a lot of time and energy to hunt game and gather nuts and berries.
Experts note that even 50 years ago it was easier to maintain a healthy weight in the United States. There were no computers and TV programs turned off 23; people stopped eating because they went to bed. Portions were much smaller. There was more work and play outside and there was generally more exercise.
With the Internet, TV and other entertainment available 24/7, many adults and children stay awake longer to watch TV, scroll through social media, play games and chat online. This can mean snacking all day – and most of the night.
Extra calories and less activity can mean a higher risk of obesity, type 2 diabetes, heart disease and other diseases. Scientific studies show that intermittent fasting can help reverse these trends.
How does intermittent fasting work?
There are several ways to practice intermittent fasting, but they all rely on choosing fixed periods of time to eat and fast. For example, you can try eating for only one eight-hour period each day and fasting the rest. Or you can choose to eat just one meal a day two days a week. There are many different intermittent fasting schedules.
Mattson says that after hours without food, the body depletes its sugar stores and begins to burn fat. He calls this asmetabolic shift.
“Intermittent fasting is in stark contrast to the normal eating habits of most Americans, who eat all night long,” says Mattson. “If someone eats three meals a day, plus snacks, and they don't exercise, they're using up those calories every time they eat and not burning their fat stores.”
Intermittent fasting works by extending the period of time in which your body has burned the calories you consumed during your last meal and starts burning fat.
Intermittent fasting plans
It is important to consult your doctor before starting intermittent fasting. Once you get his or her green light, the practice is simple. You can choose onedaily access, which limits daily eating to a period of six to eight hours per day. For example, you can choose to fast 16/8: eight hours of eating and sixteen hours of fasting.
Although some people find it easy to stick to this pattern in the long term,a research studywhich was not specifically designed to look at an intermittent fasting pattern, found that limiting your daily window for eating does not prevent weight gain over time or produce significant weight loss results. The results of this study showed that reducing the number of large meals or eating more small meals may be associated with minimizing weight gain or even weight loss over time.
Another intermittent fasting plan known as5:2 access, means that you eat regularly five days a week. Limit yourself to a 500-600 calorie meal on the other two days. An example would be if you choose to eat normally every day of the week except Mondays and Thursdays, which are your one-meal days.
Longer periods without food, such as fasting periods of 24, 36, 48 and 72 hours, are not necessarily better for you and can be dangerous. If you go too long without eating, you can actually encourage your body to store more fat in response to hunger.
Mattson's research shows that it can take two to four weeks for the body to adjust to intermittent fasting. You may feel hungry or cranky as you get used to the new routine. But, he notes, subjects who make it through the adjustment period often stick to the plan because they notice they feel better.
What can I eat during intermittent fasting?
When you are not eating, water and calorie-free drinks such as black coffee and tea are allowed.
During your eating periods, eating normally doesn't mean you go crazy. Research shows that you're not likely to lose weight or become healthier if you pack your feeding times with high-calorie junk food, super-sized fried foods and treats.
But what some experts like about intermittent fasting is that it offers the opportunity to eat and enjoy a variety of foods. Sharing good, nutritious food with others and enjoying the meal experience is satisfying and supports good health.
Most nutritionists considerMediterranean dietas a good plan for what to eat whether you try intermittent fasting or not. You can't go wrong choosing leafy greens, healthy fats, lean proteins and complex, unrefined carbohydrates like whole grains.
Temporary fixed benefits
Research shows that intermittent fasting does more than just burn fat. Mattson explains, “When changes occur with this metabolic switch, it affects the body and brain.”
One of Mattson's studiespublished inNew England Journal of Medicinerevealed data on a number 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 from chronic diseases such as type 2 diabetes, heart disease, age-related neurodegenerative disorders, even inflammatory bowel disease and many cancers,” he says.
Here are some benefits of intermittent fasting that research has shown so far:
- Thinking and memory. Research has shown that intermittent fasting increases working memory in animals and verbal memory in adult humans.
- Heart health. Intermittent fasting improved blood pressure and resting heart rate, as well as other heart-related measurements.
- Physical performance. Young men who fasted for 16 hours showed fat loss while maintaining muscle mass. Mice fed on alternate days showed better running endurance.
- Type 2-diabetes in obese people. Animal studies have shown that intermittent fasting prevents obesity. And in six short studies, obese adults lost weight through intermittent fasting. People withtype 2 diabetesmay be helpful: Most of the available research shows that intermittent fasting can help people lose their body weight and lower their fasting glucose, fasting insulin, and leptin levels, while reducing insulin resistance, lowering leptin levels, and increasing adiponectin levels are being increased. Some studies have shown that some patients who practiced intermittent fasting under the supervision of their doctor were able to reverse their need for insulin therapy.
- Tissue health. In animals, intermittent damage to solid tissue during surgery reduced and improved outcomes.
Is intermittent fasting safe?
Some people try intermittent fasting to control their weight, and others use the method to treat chronic conditions such as irritable bowel syndrome, high cholesterol or arthritis. But intermittent fasting isn't for everyone.
Before you try intermittent fasting (or any other diet), check with your doctor first. Some people should avoid intermittent fasting:
- Children and teenagers under 18 years of age.
- Women who are pregnant or breastfeeding.
- People withtype 1-diabeteswho use insulin. Although a growing number of clinical studies have shown intermittent fasting to be safe in people with type 2 diabetes, no studies have been conducted in people with type I diabetes. Mattson explains, "Because people with type I diabetes use insulin, there is concern that an intermittent fasting eating pattern could result in unsafe levels of hypoglycemia during the fasting period."
- Those with a history of eating disorders.
But people who do not fall into these categories and who can safely fast intermittently can continue the regimen indefinitely. It can be a lifestyle change, and one with benefits.
Remember that intermittent fasting can have different effects on different people. Contact your doctor if you experience unusual anxiety, headaches, nausea, or other symptoms after starting intermittent fasting.
