The Ins & Outs of Intermittent Fasting

It seems like everybody's talking about intermittent fasting. From Hollywood celebrities to social media influencers to work colleagues and friends, you've probably heard about this nutrition craze. So what is intermittent fasting, exactly, and why is it so popular? Is intermittent fasting safe? Does it really work?

Follow along and let's find out.

What is Intermittent Fasting?

Unlike most diet plans that focus on what you eat, intermittent fasting is a schedule that dictates when you eat. There are several different approaches to intermittent fasting, all of which include periods of regular eating and periods of restricted eating or fasting. The most popular intermittent fasting programs are:

• 16:8 method In this intermittent fasting schedule, you eat all of your meals and snacks within an 8-hour window, then fast for a period of 16 hours (usually including the time that you sleep), and repeat.

• 5:2 method This program calls for 5 days of regular eating and 2 non-consecutive days of restricted eating each week. On the restricted days, caloric intake is limited to 500-600 calories.

• Eat-Stop-Eat method With this method, you fast completely for a full 24 hours, usually once or twice a week.

Although intermittent fasting calls for adherence to scheduled periods of fasting or reduced eating, it does not dictate calorie consumption or any specific nutritional guidelines during the periods of regular eating. For some people who practice intermittent fasting, total caloric intake remains the same. Others may experience a reduction in calories, simply because they cannot consume as much as usual during the shortened periods of regular eating.

Benefits of Intermittent Fasting

The bulk of scientific studies on intermittent fasting, especially those which analyze long-term effects, have been conducted on animals. However, according to a recent review in the New England Journal of Medicine, human studies thus far appear promising. “Preclinical studies and clinical trials have shown that intermittent fasting has broad-spectrum benefits for many health conditions, such as obesity, diabetes mellitus, cardiovascular disease, cancers, and neurologic disorders,” states the author, neuroscientist Mark Mattson, Ph.D. While intermittent fasting for weight loss is one of the main reasons so many people are eager to try this diet plan, “intermittent fasting seems to confer health benefits to a greater extent than can be attributed just to a reduction in caloric intake.”

In addition to weight management, the studies conducted to date, along with a gret deal of anecdotal evidence, suggest that intermittent fasting may lead to benefits including:

• Decreased inflammation

• Improved digestive function

• Stabilized blood sugar levels

• Improved brain and memory function

• Increased stress resistance

• Decreased blood pressure

• Decreased cholesterol

• Improved resting heart rate

• Improved skin

How Does Intermittent Fasting Work?

Intermittent fasting works on the premise of something known as metabolic switching. Simply put, this is the change that occurs when our bodies switch from a fed state to a fasted state. In a fed state, which continues for several hours after eating, the body absorbs and digests food. Insulin levels are high and the body does not burn fat. The fat-burning process begins once insulin levels are lowered and our stores of sugar-based fuel have been used up. Then, in a fasted state, the body is able to convert fat to energy which results in a reduction in fat and retention of lean muscle mass.

The ideal time frame for fat burning is 12 hours after eating. Since a typical daily diet includes three meals and numerous snacks, we don't often experience this metabolic switch and rarely, if ever, reach the ideal fat-burning window.

Is Intermittent Fasting Safe?

For people who already favor healthy eating and who do not have underlying health issues, intermittent fasting is most likely safe. There are some people who are not good candidates for intermittent fasting, however. These include people with a history of eating disorders, people on blood-sugar medication, and pregnant women. Additionally, intermittent fasting can lead to yo-yo dieting. Therefore, as with any diet plan, we recommend consulting with your doctor or a professional nutritionist before attempting an intermittent fasting program.

Intermittent Fasting for Athletes

Intermittent fasting may be a good idea for athletes depending on the type of athlete and their training and competition plans.

For athletes looking to lose weight while maintaining lean muscle mass, intermittent fasting can help. In addition, many of the other potential benefits of intermittent fasting may be appealing. In one study focused on male athletes following an every-other-day fasting protocol, subjects exhibited better energy efficiency and higher stress tolerance after six weeks on the program. However, it's critical for athletes to eat sufficient calories to fuel their workouts and consume quality nutrients to support the stresses of training and the process of recovery. A lack of nutrients can lead to increased risk of injury or illness, and a lack of fuel for energy can result in lackluster performance.

Athletes may find that intermittent fasting is more appropriate during periods of relatively short, low-to-moderate intensity training. For periods that include high-intensity workouts and long training sessions, intermittent fasting may not provide enough nutrients and fuel. Alternately, adjusting the timing of fasting and/or exercise may help. For example, you might try:

• Following a 16:8 program with a feeding window that begins at breakfast, in order to fuel your morning workout

• Changing the time of your workouts to better fit your fueling window

• Following a modified fasting plan (such as 14:10) that allows more time to feed and train

Endurance athletes (such as long-course triathletes, cyclists, and marathon runners) typically need more fuel, more frequently to sustain their efforts; therefore intermittent fasting may not be their best option for optimal performance. That said, most endurance athletes know the beneficial feeling of eating a relatively early dinner and omitting late-night snacks, thus allowing the body to fully digest and awaken feeling light and ready to attack the next day's training or race. A modified fasting plan that simply eliminates eating after a certain hour each night (6:00 or 7:00 p.m., for example) may work well for this type of athlete.

Tips for Intermittent Fasting

If you're interested in giving intermittent fasting a try, here are a few tips to help you transition to a scheduled eating plan.

• Start slowly. Ease into your intermittent fasting program so that the change is not a shock to your system, physically or emotionally. Chances are, you already fast from 10-12 hours each night. Add 30 minutes at a time to this period over the course of a few weeks as a way to gradually expand your fasting window. If you want to try the 5:2 method, slowly reduce the amount of calories you eat on the restricted days. And if you choose to fast altogether one or two days a week, try fasting for half days to start.

• Eat healthy. Sure, you can eat whatever you want during your feeding windows. But if you suddenly switch to a fast-food diet, you're guaranteed to do more harm than good to your body, no matter how strictly you follow an intermittent fasting plan. Focus on eating healthy foods including quality lean protein, whole grains, and plenty of fruits and vegetables. You'll reap the benefits of consuming ample nutrients and fiber, plus you'll be less likely to suffer sugar crashes and junk-food cravings during the times that you fast.

• Stay hydrated. It's always important to stay hydrated to help all the systems in your body function properly. Normally, we get around 20 percent of our water intake from food, so while you're not eating, be sure to continue hydrating. Water can also help fill you up when you feel a snack craving especially as you initially adjust to a new fasting plan. Some herbal teas, like cinnamon, are even thought to help suppress the appetite.

• Be the boss. In the same way that you are in charge of following your new diet protocol, you should also feel empowered to give yourself an occasional day off. Have friends getting together for a celebratory dinner at 7:00 p.m., yet your fast typically begins at 5:00? Go and eat and enjoy! An occasional indulgence won't undo the work you put in adhering to your plan the majority of the time.

• Prep smart. Finally, if you decide to try intermittent fasting, arm yourself with the tools you need for success. Stock your pantry with healthy, wholesome goods so that you'll have plenty of nutritious food right at hand when it's time to chow down. Arm yourself with a BlenderBottle¬Æ shaker and your favorite protein powder supplement to ensure you get enough protein. And keep a jug of water (like the BlenderBottle¬Æ Koda) or a large water bottle (like the 32-ounce Owala‚Ñ¢ FreeSip) at your side always, in order to stay on top of your hydration.