You’ve probably heard some chatter about it while waiting for your morning coffee, or in line at the grocery store. But no matter where you came in contact with it, people are seriously into intermittent fasting. Just like most health trends, there’s a lot to learn about fasting, with misconceptions about its benefits and potential side effects. So before you get started on the latest craze, here’s what you need to consider.
What is intermittent fasting exactly?
According to Harvard Health, Intermittent fasting “involves alternating intervals of extreme calorie reduction with periods of normal eating.” And while there are many opinions about the pros and cons of fasting, Dr. Lori Shemek makes a good point: Fasting isn’t new. Only a few thousand years ago, humans were “switching between fasting for days (they didn’t have easy access to food like we do today) with an occasional binge (once you kill a mammoth, you have to eat it fast, before it went bad!).”
Some of the more modern techniques include:
- The 5:2 diet: Followers of this approach fast two days per week then eat normal (healthy) food the other five. The two days shouldn’t be consecutive.
- The 16:8 method: The 16:8 technique involves eating normal meals during an eight-hour window, followed by a break from food for 16 hours. This method can be easier because you’re asleep for much of the time.
- Alternate-day fasting: Just like it sounds, alternate fasting involves fasting every other day.
Fasting and weight loss
Dr. Adam Perlman at the Duke Center for Integrated Medicine says intermittent fasting can result in weight loss and increased muscle mass because the body burns more stored fat for energy. It can also boost the metabolism, decrease appetites and improve energy levels.
However, there are many studies that are not definitive on whether that’s actually true, and many flat-out refute Perlman’s claim. In fact, one study by JAMA Internal Medicine found no difference between fasting and a regular reduced-calorie diet. So what’s the takeaway? Fasting can have many different effects on different people, and it’s ultimately up to an individual preference.
If you’re ready to try fasting for yourself, “Eat, Stop, Eat” author Brad Pilon says you have to pretend like your fast never happened. “No compensation, no reward, no special way of eating, no special shakes, drinks or pills,” he says.
This is not easy for most of us. “It’s human nature for people to want to reward themselves after doing very hard work, such as exercise or fasting for a long period of time,” says Dr. Frank Hu of the Harvard School of Public Health. “So there is a danger of indulging in unhealthy dietary habits on non-fasting days.”
Fasting Pros
Wayne B. Jonas, M.D., the executive director of Samueli Integrative Health Programs, told NBC News that giving the body at least 10 to 12 hours without food benefits its natural cleansing process. This can result in improved alertness and attention, reduced risk of illness, and a longer and healthier life overall. At the very minimum, he says, it helps one eat more mindfully.
Food addiction counselor Erin Wathen adds that fasting gives your body a break from constantly processing food. “This is a huge benefit for our GI tract, appetite control, sleeping, and even our teeth,” Wathen says. “Which will benefit from reducing how often we ask our bodies to metabolize food.” Some studies indicate that intermittent fasting may also help with:
- Anti-aging
- Boosting immune function
- Improving blood pressure and heart rate
- Reducing inflammation associated with chronic disease
- Reducing the risk of cancer and other diseases
Fasting Cons
One of the leading concerns with intermittent fasting is that it can cause hormonal imbalances, leading to insomnia, stress and thyroid problems. It may also lead to an increase in unhealthy cholesterol levels that cause heart problems.
Dietician Lisa Cooper says initial side effects of fasting can include low blood sugar, headaches, irritability, dizziness, nausea and fatigue. It may also impact your performance at work if your energy or focus suffers. It can also have adverse effects on your social life; it can be difficult to socialize with friends over dinner if you can’t eat after 6 PM.
For these reasons, many “fall off the wagon” because fasting isn’t sustainable for them in the longer term.
Trying it for yourself
Fasting isn’t for everyone — especially if you’re pregnant, diabetic or prone to eating disorders. You should always practice caution when it comes to undertaking a new dietary program and consult with your physician beforehand.
However, if you’re interested in intermittent fasting, start gradually. Many experts recommend fasting for 12 hours followed by 12 hours where you can eat. If you’re happy with your results, you can build from there. The one thing to take away from fasting, or diets of any kind, is that the goal is to develop healthy eating habits that are sustainable for you. So listen to your body, and you can learn what will be most effective for you.