Intermittent fasting is the old diet craze that’s new again. In fact, throughout human evolution, fasting has been a part of existence, mainly because there simply wasn’t always food.

Hippocrates himself, the father of modern medicine, was a proponent of fasting to cure illness. The founder of toxicology and one of the three medical professionals who basically created western medicine, Philip Paracelsus, was also a big fan of fasting for health reasons.

With all that history behind it, here is how intermittent fasting can still be useful in the 21st century.

Modern Fasting as a Diet

While we know that the human body can survive for extended periods of time without food, how is that used as a diet? One key distinction to make is the difference between starvation and fasting.

Fasting is a choice, unlike starvation (outside of anorexia), and it usually involves abstaining from food or limiting foods for a set period of time. It’s typically linked to some concept of cleansing, whether physically, mentally, or spiritually.

The current trend is the intermittent fasting diet, which means that there are cycles of fasting and then cycles of eating as you normally would. It’s an eating pattern rather than an actual diet in which specific foods are encouraged or discouraged.

How to Start an Intermittent Fasting Diet

There are a few different intermittent fasting trends right now. You can pick which one suits you best.

As with any diet, but especially with one involving the cessation of eating for any amount of time, you should check with your doctor to understand any risks involved prior to beginning the diet.

The 16/8 Method

This is sometimes referred to as the leangains protocol, and it basically involves skipping breakfast. The real protocol says to consume all of your daily calories in an 8-hour period and then fast for the remaining 16 hours.

For most people, this means skipping breakfast and beginning your eating cycle at lunch. The key is to remember that, even though you’re allowed to have beverages during the fasting period, they need to be calorie-free.

Eat-Stop-Eat

This method is a little more difficult, but it involves fasting for a full 24 hours a couple of times a week. Typically, you stop eating before dinner one day and then don’t resume eating until dinner time the next day.

The 5:2 Diet

If the eat-stop-eat plan is too difficult for you, this one might be easier. The goal of this diet is still to eat normally five days a week and then fast on two non-consecutive days, just like the eat-stop-eat.

The difference is that this fast allows you to consume 500-600 calories on those two days, so you get some relief if a full day’s fast is too hard.

Why Fasting Works

One thing to remember if you decide to try a fasting diet is that on the days you’re not fasting, you should not “make up for it” by eating a lot of junk or an unbalanced diet. You still need to keep your diet healthy and well-balanced to really see the positive effects of fasting.

There are a few different ways that fasting works, and there have been many different fasting studies that show it has benefits throughout the body, not just its relation to weight.

Human growth hormone: When you’re fasting, your body adjusts hormone levels to make stored body fat more accessible to use as energy.

Insulin levels: Insulin levels drop when your body isn’t processing food. When your insulin is lower, it makes the fat in your body a key source of energy.

Cellular repair: When the body is deprived of food, your cells begin to consume old and dysfunctional proteins from inside themselves. By doing this it initiates a cellular repair process.

Gene expression: When you fast, there are changes in your genes which studies suggest help your brain age with less vulnerability. Similarly, changes have been seen that have significant implications for the prevention or treatment of cancer.

Weight loss: While there may be a number of different health benefits to fasting, many people do it for weight loss alone. Simply eating fewer calories can lead to weight loss, but it’s believed that the changes in your hormones can also increase your metabolism, further inspiring weight loss.

Who Can Safely Fast?

Again, as with all diets, it’s best to consult your health care provider if you have any health concerns that might be affected. Of primary concern are people with diabetes or blood sugar regulation issues, low blood pressure, and those who take certain medications.

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Beyond that, people who have a history of eating disorders should probably not attempt this diet.

There are some concerns about women who do an intermittent fasting diet and have changes in their menstrual cycles. This has been noted, but no significant studies support this. If you do have this problem, it’s best to speak with your doctor or stop fasting.

Similarly, an intermittent-fasting diet is not a good idea for any woman who is looking to conceive, is pregnant, or is breastfeeding.

The Bottom Line

Fasting is nothing new—it’s probably been a part of the human experience since the first humans walked the earth. There have been many different reasons for fasting, from health concerns to religious practices.

By regularly practicing short fasts your body goes through a number of changes that can help you lose weight, control blood sugar issues, benefit from healthier brain aging, and maybe even fight cancer.

The different intermittent fasting diets give you options to find a manageable approach that works for you. Just remember not to make up for lost calories by overeating on the other days.

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