The health benefits of intermittent fasting

Spend any amount of time in health and fitness groups or following fitness Instagram accounts and you’re bound to see people posting about intermittent fasting (IF). What’s the deal with fasting? How do you do it properly? And is it really good for you?

I always have to laugh when people say that fasting is unnecessary or dangerous or even some trendy new fad diet. Fasting has literally been around since the beginning of time. Food scarcity often necessitated periods of prolonged fasting or lower calorie consumption. And it turns out, this pattern of eating has health benefits.

Nowadays, we’re so used to being able to grab food at the first twinge of hunger that fasting seems like a crazy concept. But there are benefits to resting your digestive system. Well-meaning health professionals are also fond of saying that fasting and cleansing aren’t necessary because our bodies already have a built-in detoxification system. This is true. If we let it do its job. Which we usually don’t, because most of us are constantly eating, and eating foods that are hard to digest. But your body can’t digest and detoxify at the same time. So when we eat three large meals a day, and snack all the time, and eat late at night, and eat foods that are hard on our system, we never actually let our detoxification system kick in.

What’s your toxic load?

People also like to pretend that toxic buildup in the body isn’t a real thing. But toxins are all around us: in our food, in the air we breathe, in products that we put on our skin. We consume foods laden with pesticides, preservatives, hormones, and other chemicals. These things can accumulate in our bodies if we don’t allow our detoxification systems to properly dispose of them.

In his excellent book, Clean: The Revolutionary Program to Restore the Body’s Natural Ability to Heal Itself, Dr. Alejandro Junger explains it like this: imagine your body is full of tiny garbage men who are just trying to do their job and clear out all the junk that accumulates. But they’re so busy bagging up all the trash, they don’t actually have time to take it to the dump. So it just sits there, causing inflammation, interfering with normal biological functions, disrupting our hormones and our metabolism, and causing all kinds of problems like sinus congestion, joint pain, skin issues, fatigue, excess weight, brain fog, etc.

When you stop eating all the time and let your digestive system rest, the garbage men can actually do their job and dispose of all the built-up toxins so that you can start healing.

How fasting helps

When we give our digestive systems a break, we allow the body to enter healing and rejuvenation mode, which can have widespread health benefits.

But first, the body has to get rid of all those accumulated toxins. This is why, when you first start a cleanse or a fast, you may actually feel worse. All of those toxins are being mobilized so you can eliminate them. You may seriously feel like garbage. People often think this means the diet isn’t working, because it’s making them sick. Unfortunately, you just have to get through this part of it. The greater your toxic load, the worse you’ll probably feel.

The good news is, you typically only have to go through this once. If you’re fasting on a regular basis, it will get easier every time you do it.

Benefits of fasting

Recent research, much of it from the Longevity Institute at the University of Southern California, has demonstrated numerous benefits associated with periodic fasting, including:

  • Reduced risk of chronic diseases such as cancer and heart disease
  • Increased lifespan and healthspan (the period of your life characterized by good health)
  • Improved markers associated with biological aging (such as inflammation)
  • Increased energy
  • Improved cognitive performance


Fasting can also help with weight loss. People often assume that’s because you’re simply eating less, but it’s actually more complex than that. Studies have shown that people lost more weight when practicing periodic fasting, even if their total caloric intake remained the same. Allowing your body to enter its rejuvenation and healing state can help reset your metabolism and restore many normal biological functions that impact your weight, such as hormone regulation, thereby making weight loss easier.

How to fast

Good news: Fasting doesn’t have to mean going completely without food. You can approach fasting in several different ways, such as restricting all of your food intake to a certain time period, or reducing your caloric intake on certain days.

Time-restricted fasting

When people talk about intermittent fasting, they’re often referring to the practice of time-restricted fasting, in which all food consumption is limited to a certain window. A common approach is 16:8 IF, where you fast for 16 hours and then eat all of your food during an 8-hour period. For example, that might mean you eat all your meals between 10:00 am and 6:00 pm. This gives your body more time to process everything and rest.

This type of practice naturally goes hand in hand with a ketogenic diet, because once you’re keto adapted, your appetite typically stabilizes and you simply aren’t as hungry.

Alternate-day fasting

Another form of intermittent fasting involves restricting your food intake on alternate days. A common version of this is the 5:2 diet, where you eat your regular diet 5 days of the week and eat fewer calories on two non-consecutive days. For example, you could eat a reduced-calorie diet on Tuesdays and Thursdays. Vegetable soups and green smoothies are good foods to ingest on these days, as liquids require less work for your body to digest, thus allowing your body to get back to rejuvenation mode sooner.

Prolonged fasting

Prolonged fasting refers to the practice of reducing your food intake for at least 5 days, focusing on liquids, greens, and non-starchy vegetables. This can have dramatic results and is best for people who have chronic health issues related to diet. If you’re already on a low-carb diet, something this drastic may not be necessary but could still be used to reset your system if necessary.

Prolonged fasting is particularly beneficial for those who have undiagnosed food sensitivities. Foods such as eggs and dairy are common causes of issues such as gastrointestinal distress, acne, and sinus problems. Nightshade vegetables — tomatoes, bell peppers, and eggplants — are another common source of food sensitivities. A prolonged fast can allow you to clear these foods from your system and then reintroduce them one at a time so you can identify any foods that are causing reactions.

A few general guidelines

Whichever approach you take to fasting, you’ll experience the best results if you’re otherwise eating a healthy plant-rich diet. Support your fast with foods that help boost your immune system and build your health, such as lots of leafy greens and green tea.

For the best results, fasting should be a regular practice. You can also combine the above approaches. For example, you could do a prolonged fast at the beginning of the year — especially if you tend to over-indulge during the holidays — and then begin regular intermittent fasting. The more you do it, the easier it will become, and the more benefits you’ll likely experience.

This post first appeared on Low Carb Soul. Reposted with permission.