A How-to Guide to Intermittent Fasting | The Paleo Diet®
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What to Eat If You’re Intermittent Fasting

By Megan Patiry, Lifestyle Writer
May 19, 2021
vetre/ Shutterstock.com
vetre/ Shutterstock.com

For thousands of years, fasting has been practiced for spiritual purposes, as a method to help treat various diseases, or because of a simple lack of food.

Fasting as a method to treat diseases showed success even in ancient times, with Hippocrates claiming that fasting could prevent or lessen the severity of epilepsy. [1] Now, modern research on fasting has exploded, with hundreds of studies showing benefits like increased stress resistance, decreased risk of diabetes, longevity, and even reduced cancer risk. [2]

If you’ve considered giving the modern approach to regimented fasting—termed intermittent fasting (IF)—a try, be sure to do it mindfully. Many people jump into intermittent fasting and hit a wall immediately. If you’ve tried it, perhaps it left you light-headed, irritable, shaky, and weak … not to mention extremely hungry!

Here’s the key to remember: Regardless of when or how many hours you fast, it’s what you eat when you’re not fasting that can make or break it. Here’s how to maximize your eating time to make sure you fuel yourself properly through the process.

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Why the foods you eat affect your success with IF

It’s a common belief among the intermittent fasting community that, because you are eating within a smaller window during the day, you can eat whatever you want and still avoid gaining weight. The logic goes that it should be difficult to get in enough calories for the day in such a short time frame (typically a 6–8-hour window).

There’s also a lack of discussion and understanding about what types of foods you should be eating at mealtime.

True, some people can get away with eating whatever they desire during their eating window and not gain weight; however, this doesn’t necessarily mean that their strategy is healthy. It simply means that their calorie count isn’t high enough to cause them to gain weight.

The problem with taking the “eat whatever you desire” advice during your eating window is that it is not only unhealthy advice, but it can easily backfire for most.

Why?

Simply put, fasting (especially if you’ve never practiced it before) is a bit of a shock to your body on various biochemical levels, and it will take a bit of metabolic readjustment to get used to.

It is recommended that if you’re eating a high-carb or not-so-clean diet now, to adjust your diet to a Paleo Diet template before you try intermittent fasting.

What do I mean by “metabolic readjustment?” For example, if you take a person who has been consuming high amounts of processed carbs and sugars, which have been spiking their blood sugar for years, then suddenly remove all glucose and sugar from their diet for a huge chunk of time, that person is going to likely experience an intense case of low blood sugar.

This will lead to them feeling shaky, light-headed, exhausted, and irritable. They may then feel “better” once they get their familiar spike of glucose during their feeding window, but because they are still eating processed carbs and sugars, they will crash immediately during their fast. And, unfortunately, this may cause them to give up fasting before their body ever has the time it needs to metabolically readjust to burning fat instead of glucose as a fuel source.

Now, contrast this with someone who has been eating a Paleo Diet of natural carbohydrate sources that don’t spike their blood sugar. Because their bodies are used to dipping in and out of their fat stores, they will likely better adjust to intermittent fasting.

This is why it is extremely important to focus on eating foods in line with The Paleo Diet® in order to truly succeed and thrive on an intermittent fasting regime. In fact, it is recommended that if you’re eating a high-carb or not-so-clean diet now, to adjust your diet to a Paleo Diet template before you try intermittent fasting.

Consuming vegetables, whole fruits, and eating plenty of wild proteins and healthy fats will help your body adjust to lower glucose levels before you dive headfirst into glucose scarcity for many hours a day.

We recommend shifting to The Paleo Diet for at least a couple of weeks before jumping into intermittent fasting.

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What to eat while you’re intermittent fasting

During your feeding window, the same rule applies: Keep it Paleo, and avoid processed carbs and sugars, as these will spike your blood sugar and cause you to feel a “crash” during your fast.

Here are the three types of foods you should focus on.

1. Healthy fats

Fats are key to making sure you’re getting enough calories during your fast, since your eating window is smaller. They also assist with satiation.

Eat plenty of avocado, cold-pressed olive oil and coconut oil, coconut milk, seeds and nuts, and eggs.

2. Wild and organic meats and fish

High quality protein is going to keep your blood sugar stable and keep you feeling full for hours.

Eat plenty of grass-fed beef, pasture-raised poultry, wild game meats, and fish like wild-caught salmon, sardines, and mackerel.

3. Fruits and vegetables

Make sure you’re getting large portions of greens and non-starchy veggies with every meal, as these bulk up your feeding window with minerals and other essential nutrients. Supplement them with smaller servings of whole-food carb sources.

Eat plenty of leafy greens like kale, collards, and spinach; starchy veggies such as sweet potato, pumpkin, and squash; berries, oranges, and avocado.

Fasting schedules

One of the great aspects of intermittent fasting is the variability of fasting schedules you can adopt. For instance, some may choose to fast every other day, others may choose to eat only once per day, and others will eat only between a short window of time every day.

Here we focus on the latter version of IF, which shortens your “feeding window,” or the number of hours within which you consume food. The reason we’re doing this is because it is considered the most sustainable form of IF, and a great place to ease into the practice of fasting.

This method of IF is also referred to as the 16/8 method, and involves fasting for 16 hours, then feeding within the following eight hours.

In essence, this will look like skipping an early breakfast, then breaking your fast at either 11 a.m. to 1 p.m., and eating your last meal between 5 p.m. and 7 p.m.

Below you can see an example of what a day of this style of IF looks like.

Sample meal plan for intermittent fasting

What to Eat If You’re Intermittent Fasting image

Ready to give IF a try? Here’s a meal plan for three days. You can try the 16/8 fasting schedule, or even use it for alternate-day fasting—just slightly increase your portions on your eating day.

Sample meal plan #1

Sample meal plan #2

Sample meal plan #3

What to Eat If You’re Intermittent Fasting image
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References

1. Mark P. Mattson, Keelin Moehl, Nathaniel Ghena, Maggie Schmaedick, and Aiwu Cheng. Intermittent Metabolic Switching, Neuroplasticity, and Brain Health. Nat Rev Neurosci. 2018 Feb; 19(2): 63–80. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913738/>

2. Rafael de Cabo, Ph.D and Mark P. Mattson, Ph.D. Effects of Intermittent Fasting on Health, Aging, and Disease. New England Journal of Medicine. 2019; 381:2541-2551. DOI: 10.1056/NEJMra1905136. <https://www.nejm.org/doi/full/10.1056/nejmra1905136>

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