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Complete Guide to 18/6 Intermittent Fasting: Pros and Cons

Picture of a wooden plate with food in one quadrant marked off with a fork and spoon to illustrate how intermittent fasting works.

Intermittent fasting has many pros and a few cons. In this article we will discuss everything about intermittent fasting. I think you’ll be excited to explore what this type of eating can do for you and your health.

What is intermittent fasting?

Intermittent fasting is time-restricted eating. People choose to utilize different time periods where they are fasting and eating. The most common recommendation is a fasting period of 18 hours and and eating during a 6-hour window. This can really be tailored to you individual needs though. You can do this daily, weekly, or even monthly and see benefits.

Fasting induces autophagy

intermittent fasting induces autophagy which makes bad cells die.

This is one of the absolute BEST and most fascinating things about fasting! It’s also a super fun word to say! Autophagy is one of the super powerful effects of intermittent fasting. This research has been around for a long time and has been proven to be very important for human health. 

The following is a quote from this article on PubMed. “Autophagy, or cellular self-digestion, is a cellular pathway involved in protein and organelle degradation, with an astonishing number of connections to human disease and physiology. For example, autophagic dysfunction is associated with cancer, neurodegeneration, microbial infection and ageing.”

What we can take away from human studies that have been done, is that eating fewer calories keeps your cells healthy and leads to a decreased incidence of disease. I’ve personally experienced symptoms like heart palpitations go away after introducing this type of eating. I’m not saying this is a promised result but just something that I have personally felt for myself. I know sharing personal things can make topics really come to life for you, so I want to try and be open and share more of my personal story with everyone!

Without calorie restriction, cells that are unhealthy will continue to live and cause damage in your body. We want them to die and be replaced with new, fresh cells in order to be as healthy as we want to be. 

Health benefits of intermittent fasting:

Man and women dressed in black jogging in nature while smiling.
  • Improves overall health
  • Decreases incidence of MANY chronic diseases
  • Decreases insulin resistance and increases insulin sensitivity
  • Decreased blood glucose levels in patients with diabetes
  • Weight loss (turns on your metabolic switch…our genetic code isn’t really built to have food around 24/7)
  • Decreases risk of heart disease
  • Decreases high blood pressure
  • Normalizes hormone levels
  • Increases energy levels
  • Boosts stress resistance
  • Slows the aging process
  • Increase brain function (decrease brain fog)

Cons of intermittent fasting

While there are many health benefits that can be achieved with the intermittent fasting method, there are also some pitfalls and negative side effects.

Drop out rate

An intermittent fasting schedule can be difficult to stick to. Our environment is very calorie heavy. Restricting calories can be very difficult without the proper social support. Like if you are trying to fast and your friend is eating your favorite food right in front of you…that may be a challenge. LOL!

Overeating on non-fasting days

It is common and tempting to increase your caloric intake more than usual right after a fast. Even though you won’t feel great if you do that, it still happens. Some people do better with a consistent eating pattern and healthy diet. Drastically cutting calories or restricting eating times can lead to binging on donuts the next day. That’s not a pattern that you want to establish because you won’t get the benefits you are looking for. 

Health conditions

While certain types of intermittent fasting work extremely well for different issues, you have to be careful. Taking medications for diabetes, high blood pressure, seizures, etc can interfere with the function of your body while on a fast. It is a really good idea to discuss different types of fasting with your provider before starting. Even with all of the potential benefits, it may not be the best choice for you. 

Intermittent fasting plan how to:

Picture of plate with a pink clock on it to represent time restricted eating with intermittent fasting

By now you know you will be utilizing time-restricted feeding. You can choose to skip breakfast and have your first meal around noon. If however, you wake up starving every morning, then choose a time window that works better for you. You may be a person that does better skipping dinner.

Choose the hours of the day for eating that work best for you and your physiology.

I will say that not eating a night will boost the positive effects tremendously! Make sure to have your last meal at least 3 hours before bed. When you extend your fasting window into this time period you’ll enjoy less inflammation, fat storage, and sluggishness. I know from experience. I love having a midnight snack but feel and look tremendously better when I don’t. One thing I can recommend is having a piece of xylitol gum at night if you are fighting a craving. It works tremendously well.

What’s the best number of hours to fast?

Black clock in center with lots of numbers all around

As I mentioned before, the most common is an 18-hour fast with a six-hour window for eating. 

If that amount of time feels overwhelming to you try longer eating window. Start with an 8-hour window and work from there.

The next day after your fast, try to break the fast with a small meal. If you go all in too quickly you may not feel well. No one wants that! Yuck!

How many days should I do?

colorful dates on small notes to represent how many days to do intermittent fasting

I’ve had patients and friends that have done SO many variations here! Here are some ideas…

  • Once a month (choose the same day if you are trying to build a habit over a period of time)
  • Once a week (like every other Thursday)
  • 5:2 Schedule (normal meal plan 5 days/week and intermittent fasting protocol 2 days/week).
  • Alternate day fasting
  • Daily (hardcore…lol)

I feel like this is a very individualized process long term. Try something for a month or two and see how it works. You may have to adjust your days of the week or transition from alternate-day fasting to the 5:2 schedule.

An easy way to approach this is to try and set yourself up for a 6 month journey. Most things we do take 6 months to show rewards/results. I love the occasional instant transformation but that isn’t the norm. If we really want to enjoy a healthy lifestyle we should be mentally prepared to settle in for a while, as much as I hate to accept that!

With all joking aside, it really has been a healthy mental shift for me to accept this. 10 years ago, I would just give up on whatever my new plan was after a month because I wasn’t seeing the wanted shift yet. When I started doing things for 6 months at a time I didn’t obsess about it. Looking at pictures from one holiday to the next is such a pleasant surprise!

Do food choices matter?

2 sets of hands holding food choices. One is junk food and one is greens.

You may be wondering…what is a good intermittent fasting diet? Or, is there a certain eating plan that works best in conjunction with intermittent fasting?

Honestly, it depends on your goals.


Let’s be honest though… eating nutrient-dense foods that can be found in nature will provide essential nutrients from your calorie intake. This is just an all around great plan no matter what the goal is for your health. Choose healthy foods and have a balanced diet. You don’t have to reinvent the wheel here. 

If you want to lose weight:

Obviously keep junk food to a minimum. Ideally if you want to induce fat loss you should create a calorie deficit. There are conditions that will change this math problem in to a real problem but for most people, limiting calories will decrease fat stores and body weight over time. Controlling your insulin levels and blood sugar is key when you are trying to lose weight. One of the best ways to do this is with a ketogenic diet.


I personally like the keto diet for many reasons. Weight loss is one of them. I like how having your body run on healthy fats also burns fat! This also makes it more sustainable for the majority of people since you can have high fat content for satiety and it doesn’t feel as restrictive. See this post about oils/fats.

You may want to check your ketone levels to get the best results. You can do a blood check with a keto mojo or go big and get a breathing instrument that can detect ketones in your breath. I personally have used the keto mojo and I thought it was fantastic!

Keto is Neuroprotective

I’m all about things that are good for your brain and nervous system. See this section of my blog if that interests you! 

The title of this study says it all “The neuroprotective properties of calorie restriction, the ketogenic diet, and ketone bodies”.

Carbohydrate Cycling

I also like a healthy diet with carb cycling. Eat carbs one day and not the next. This causes metabolic confusion so you body doesn’t know when to retain or burn calories. It just burns them all the time. Just try to choose whole grains that won’t spike your blood sugar levels too much and eat lots of lean protein to keep your muscle mass.

The mediterranean diet also ticks a lot of boxes when it comes to health and longevity. See section one of this post for more.

What foods won’t break the fast?

Not many choices here. Anything that has calories will take you out of a fasted state. It’s a bummer because I’m not very hungry in the morning and I rarely eat breakfast BUT I do need my oat milk and esspresso. Dang! 

Here’s a short list of things you can have without starting the clock on your eating period.

  • water
  • black coffee
  • herbal tea

Final thoughts:

It’s my sincere hope that you found something here that helped you and decreased your stress levels! Please let me know how I can help you further along your journey. And, please subscribe to my email list if you would like more content like this. I would also LOVE it if you would share this with someone that you think would benefit from it. 

I’m so proud of you for seeking out answers and getting better than you were yesterday! Talk to you again soon. 

Dr. Bri


The entire contents of this website are based upon the opinions of Dr. Bri, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked.

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of its authors. We encourage you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. 

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