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Is fasting right for you?

| Healthy You | Eating Right

A woman smiles while using a blender

Tips to consider how or whether to try it

Fasting dates very far back into our collective history around the world. Most cultures have had some sort of ritual that revolves around fasting, according to Jeanne Cullen, RD, a dietitian for PeaceHealth in Eugene, Oregon.

“In fact, it is also in our genetics, as it started in Paleolithic time or before,” she notes. “Hunter-gatherers would eat when they were lucky enough to make a kill, or find berries or other food growing along their route. They tended to eat a lot in those times, and then there would be times of scarcity and forced fasting.”

Some religions have also incorporated fasting into annual events, such as Lent in the Catholic religion, and Ramadan in the Muslim religion. “They must have seen the wisdom in the concept of giving the body a break from constant feeding,” she says.

Many functional medicine doctors and naturopaths recommend fasts and cleansing, as a way to heal and reset the body. Some people fast as a way to lose weight or jumpstart healthy habits to help them start to lose weight or eat better.

Jeanne has personally tried a variety of cleanses over the years, some of which have included fasting. “I have to say, I felt so good during that first weekend of fasting, that I was in a euphoric state, and had so much energy,” she says.

During the fasting state, “there is something magical that can happen.” When there is no food coming in, your body focuses on burning fat to provide the fuel needed to keep your heart, brain and other organs functioning.

Call the magic autophagy

In the 1950s a Belgian scientist, Christian de Duve, was studying insulin, when he accidently discovered a process going on in the cells, which he called autophagy.

Another scientist, in 1983, Yoshinori Ohsumi, discovered the genes that regulate autophagy. He won the Nobel Prize in 2016 for this discovery.

According to the discovery, autophagy occurs during cellular stress, says Jeanne. It is the mechanism by which cells naturally cannibalize some of their own parts, in an effort, to clean up the cell.

This appears to be one of the beneficial side effects of doing a fast—whether a total fast or intermittent fasting.

“Since your body is not expending energy to break down and digest your food, it gives it an opportunity to make new stem cells,” says Jeanne. Also, your existing cells start to remove toxins, and repair damaged tissue.

During times of extended fasts, your cells have time to clean up cellular debris that has accumulated in the body. “This is partly what makes you feel better during and after a fast,” she notes.

Many people report having more energy with fasting because the body isn’t burdened by having to digest foods constantly. It’s also because of the clean-up happening in the cells.

Is fasting right for everyone?

So, is fasting right for everyone? No. For people who have certain conditions or who take certain kinds of medications, fasting might not be beneficial and for some, it could even be harmful. Talk with your doctor about your desire to try fasting before you proceed.

For example, if you have diabetes and use medications and/or insulin to manage your condition, you would definitely want to discuss with your doctor whether it is safe for you to undertake a fast. It could require adjustments to your medications or insulin. Work closely with your doctor before trying it.

Different ways to start a fast

If you’re in good general health and your doctor has no concerns, you can choose how you fast and for how long. Keep in mind there are different ways to fast.

“For someone doing a fast for the first time, I recommend starting with a one-day fast, and no more than two or three days,” says Jeanne. No matter what, it is imperative to drink plenty of good quality water during a fast.

Many people will do a vegetable juice fast, and that is a great way to fast since it gives the body good nutrients to support the fasting process. “If that’s your fast of choice, use fresh vegetable juices, which will give you some fiber and flavor,” notes Jeanne. “Celery is a common vegetable to juice, but you can also juice other vegetables, such as cucumbers, spinach, kale, lettuce, and I would always add a small amount of apple or carrots, to make it more palatable.”

Some people will opt for a water fast—consuming water only. Purists will drink water without any flavoring, but there’s nothing wrong with adding a hint of fresh flavor with a lemon wedge, cucumber slice or a sprig of mint. “For a water fast, if you are doing it for the first time, I would limit it to one or two days, at the most because fasting—especially your first one—can be a challenge,” she says. “Keeping your first fast experience short can make it more positive and give you a feel for whether you might want to try fasting again.”

If you're in the middle of your fast and have a difficult time keeping your mind off of food, here are a few tricks to try:

  • Sip some water. You might even vary the temperature of the water.
  • Do some light activities as a distraction--call a friend, read a book (that's not about cooking or eating), work on a puzzle or go for a walk.
  • Avoid sources of temptation--places or activities that trigger hunger pangs. Steer clear of the kitchen. Take a break from watching TV or reading magazines with food-related advertising.
  • Remind yourself your fast is only temporary; give yourself a pep talk about why you're doing the fast. Be sure to note how you feel before and after your fast, for future reference.

Intermittent fasting 

Intermittent fasting is another approach that has become popular recently. It is easier than doing a water or juice fast, and it can be equally as beneficial, shares Jeanne.

“With the intermittent fast, you are essentially narrowing your window of eating to around eight to 10 hours.” Most people who use intermittent fasting will skip breakfast in the morning, and then have two meals with one or two snacks within a shortened window of time for eating during the day. 

On an intermittent fast, you can eat the same amount of food you would normally eat, including lean protein, lots of vegetables, healthy fats, high fiber carbohydrates, and a moderate amount of fruit.

For example, a 16-hour fast would mean not eating anything between 8 p.m. and noon the next day. Your body naturally fasts for the seven to nine hours that you’re sleeping.

When you wake up, you’d drink one or more glasses of water. Eat your first meal of the day at noon, followed by a small balanced snack at 3 p.m., dinner at 6 p.m. and another snack at 8 p.m. Repeat the steps again for a day or as many as you feel would work for you.

Begin—and end—with a plan

“Before you begin, it is good to set up parameters for what you want to achieve. Depending on how you feel, you can make additional adjustments such as cutting your fasting period short or extending it longer,” she says.

While several aspects of fasting are an individual choice, Jeanne doesn’t recommend doing water or vegetable juice fasts more than a couple times a year. And if you have never done a water or juice fast before, go slow, and work with your doctor or nutritionist.

Intermittent fasts can be done more often and for longer periods since you are eating the normal amount of food—just within shorter windows of time each day. Again, consult your doctor if you’re taking medications that might affect how and when you eat.

Start with a plan and see what happens.

  • Set yourself up for success in advance. Before starting a fast, avoid buying or making food that will continually lure you into the kitchen.
  • Ask your family or others in the household to keep you accountable.
  • Adjust things as you proceed, depending on how you are feeling.
  • Take notes to help understand how your body is responding to the fast. That can also help you decide whether you would consider doing a fast again and what to expect.