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Intermittent fasting is one of the most popular dieting trends in the last several years, including intermittent fasting on keto. However, much like the keto diet itself, intermittent fasting for beginners can be difficult to understand and execute correctly. This guide will tell you everything you need to know: how to intermittent fast, intermittent fasting benefits, and how it aligns with a low carb lifestyle so you can enjoy everything this way of eating has to offer.
What Is Intermittent Fasting?
Intermittent fasting is an intentional approach to eating that cycles between periods of eating and periods of fasting (aka, not eating). It doesn’t tell you what to eat, so it’s not a diet — it influences when you eat instead. That means you can not only practice intermittent fasting on keto, but on any kind of eating plan.
Although humans have fasted for thousands of years out of necessity (in times of food scarcity) or for religious reasons, people now use intermittent fasting for weight loss and other health benefits.
Does Intermittent Fasting Work For Weight Loss?
Is it practical to do intermittent fasting for weight loss? Absolutely. Studies show that intermittent fasting can naturally restrict calorie intake and appetite, which can lead to weight loss [*].
However, intermittent fasting also works on a hormonal level by releasing more norepinephrine, a fat burning hormone. This hormonal shift can increase your resting metabolic rate [*, *], which means you can burn more calories, more efficiently — even in a resting state.
By restricting calories and increasing the rate at which you burn calories, an intermittent fasting schedule can lead to weight loss.
How Does Intermittent Fasting Work?
Although an intermittent fasting plan works for weight loss, it also kickstarts other biological processes depending on how long you do it:
- Intermittent fasting results occur as soon as 12 hours after you stop eating. At this point, the body enters ketosis, stabilizes blood sugar, and switches from using its preferred glucose stores to burning stored fat [*].
- Fasting even longer (up to 24 hours or more) generates more ketones and burns more fat, and signals the body to begin cellular recycling and repair [*].
- Longer intermittent fasting hours (48 or more) can help build muscle and even create new immune cells [*, *]. However, this is not a recommended approach to intermittent fasting for beginners.
Intermittent Fasting Benefits
Fasting, especially intermittent fasting on keto, allows you to gain an array of key health benefits:
Reduce insulin and blood sugar levels.
Fasting lowers insulin levels and triggers fat burning mechanisms in the body [*]. After a short period of hunger while your body adjusts to fasting, this approach also stabilizes blood glucose levels [*].
Strengthen cardiovascular health.
Fasting is linked with better markers for heart health, including lowered cholesterol and blood pressure [*].
Slow down aging.
Fasting “turns on” a cleanup process in the body called autophagy, which protects against oxidative stress and can help keep your cells younger [*].
Reduce disease risk.
Burn stubborn fat.
Studies show that intermittent fasting targets and burns more visceral fat, the tough-to-lose fat around your midsection [*].
Gain mental clarity.
Enjoy more convenience.
Intermittent fasting cuts down on decision fatigue over what to eat, time spent on cooking, and food cleanup. When you don’t stop to eat as much, you can spend more time on other things.
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How To Intermittent Fast
Intermittent fasting on keto is easy, as long as you follow a few simple guidelines.
Intermittent fasting rules:
- Decide how long you want to fast. Start with a smaller fasting window (such as 12 hours) and build your way up. (Note: Sleeping can count toward your fasting window.)
- Avoid eating during your fasting window. You may drink zero-calorie beverages such as plain water, tea, or black coffee.
- Stay hydrated. Water is most important, but you can also have plain tea or coffee. If you fast for longer periods, add electrolytes to avoid keto flu.
- You can exercise during your fasting window, but you may want to do it closer to your eating window for intense workouts.
- Plan your meals before your eating window to avoid last-minute food choices when you’re already hungry.
- When your fasting window closes, re-feed with balanced, nutrient dense foods. Don’t use your re-feed time to binge or eat unhealthy, processed foods.
How to start intermittent fasting:
Wondering how to do intermittent fasting for the first time? Start with a smaller fasting window, such as 12 hours, before exploring longer fasting times.
With an early dinnertime or late breakfast (and no snacking), you can easily achieve a 12-hour fast. Then, you can experiment with the fasting schedules below.
Ideal intermittent fasting schedule:
There are no intermittent fasting times that work for everybody – experiment to find the best one for you! Here are some of the most popular ones, any of which will work as an intermittent fasting keto schedule:
- 16:8 – Fast for 16 hours, with an 8-hour eating window
- 5:2 – Eat normally for 5 days, restrict calories to 500-600 for 2 days spaced in between
- Eat stop eat – Eat normally for 5 days, fast for 24 hours two days per week (spaced apart)
- 4:3 – Fast every other day, and eat normally on non-fasting days
- One meal a day (OMAD) – Fast for 23 hours daily, eat a balanced meal during a 1-hour window
- Skip meals spontaneously when you don’t feel hungry
16:8 is one of the most popular ways to practice intermittent fasting for beginners. This keto beginner meal plan provides a way to practice keto and intermittent fasting with easy low carb meals for your eating window — just omit the breakfast to practice fasting.
Intermittent Fasting FAQs
Intermittent fasting for beginners comes with a lot of questions. Here are the most common ones:
Can you drink water while intermittent fasting?
Yes, you can and should drink water! You can also enjoy any zero-calorie beverages.
Can you drink coffee while intermittent fasting?
Intermittent fasting coffee is fine to drink, but make it plain. (Same with tea!) Avoid adding anything to it that will add calories, and thus break your fast.
Can I have cream in my coffee while intermittent fasting?
Cream contains enough calories to potentially break a fast and lose out on the benefits, so it is not recommended.
Can I have (some other thing) during a fast?
The general rule is that anything with calories breaks a fast. The main exceptions are supplements, electrolytes, and medications:
- Supplements: You can continue taking any that are recommended to take on an empty stomach. Read labels to know for sure, and pay attention to how you feel if you take them while fasting.
- Electrolytes: It’s a good idea to take these during a fast. Just make sure they don’t have calories or sugar. If you want to be less strict, you can have a keto electrolyte drink which has 8 calories, probably few enough to be okay for a fast.
- Medications: Many of these need to be taken with food or taken at certain times for optimum absorption. Talk to your doctor before changing when and how you take medications.
What to eat while intermittent fasting?
During your fasting window, you shouldn’t eat anything. 😉 During your eating window, enjoy nutrient-dense keto foods like healthy proteins, vegetables, and fats.
Avoid breaking your fast with processed foods, carb-heavy meals, and dirty keto foods, as these can hinder the health benefits of fasting in the first place.
Is intermittent fasting safe?
Research shows that people can fast successfully with mild, minimal side effects. Dangerous intermittent fasting side effects are more likely to occur when people undergo long-term extreme fasts, continue fasting despite feeling serious side effects, or re-feed with unhealthy foods [*].
Intermittent fasting side effects are minor for most people. You may feel mild hunger or weakness, and these are normal. Generally, electrolytes can minimize these side effects so the transition into fasting is not so harsh.
For the average person with no health conditions, fasting is generally safe and aligns with human biological processes for waking, metabolizing food, and repairing cells [*].
However, you should check with your healthcare provider before fasting. Fasting is also not recommended for children, pregnant or breastfeeding women, or anyone with a medical condition a history of disordered eating.
How long should you intermittent fast?
How long is intermittent fasting sustainable? When it comes to intermittent fasting for beginners, 24 hours or fewer is a safe limit.
Those more experienced with fasting may go 48-72 hours, or even longer — however, you’ll have to experiment and work up to a long fasting window, and stop if it doesn’t feel right or keeps you from doing daily tasks.
You can incorporate some form of fasting into your schedule every day, as long as you stay healthy and nourished with the right foods during your eating windows.
Is intermittent fasting keto?
This way of eating can align with keto, and some research shows that it can help you achieve better fasting results [*].
Rather than thinking of these approaches as “intermittent fasting vs keto,” they can work together to ensure you don’t feel hungry since you’ll enjoy healthy and satisfying fats during your eating widow.
Conclusion: Should You Intermittent Fast?
As long as you are generally healthy and have no underlying medical conditions, learning how to intermittent fast can help you gain all the amazing benefits of this dietary approach. Try intermittent fasting on keto to stay nourished with healthy fats, and feel less hungry during your fasting window.