Intermittent fasting and the ketogenic diet seem to go hand in hand. That’s because fasting may help support ketosis which is the primary goal of the ketogenic diet. Being in a state of ketosis is linked to many health benefits, such as weight loss, mental clarity, and improved energy.
Many people incorporate intermittent Fasting (IF) to improve overall health, reduce meal prep and decision fatigue, and remove common obstacles on the ketogenic diet. Below, we explain what it is, go over the benefits and risks, summarize the various methods, and walk you through how to safely incorporate it into your life, if it’s something you want to try.
What is Intermittent Fasting (IF)?
Intermittent Fasting more accurately describes an “eating pattern” than a “diet.” With IF, you cycle between periods of fasting and eating. It doesn’t dictate what to eat; it dictates when to eat.
Is Intermittent Fasting safe?
You’ve probably heard that to keep your metabolism chugging along, you should eat every 3-4 hours. But going through periods of fasting is actually more “natural” than eating every few hours. That’s because our ancestors (the hunter-gatherer ones) didn’t have the convenience of 24/7 access to food. They didn’t have restaurants, grocery stores, or refrigerators. They sometimes had to go extended periods of time without food due to availability. Fasting is also a part of religions, including Islam and Buddhism. In other words, humans are physically able to function without food for extended periods of time.
What’s the best way to do Intermittent Fasting?
- The 16/8 Method: Skip breakfast and restrict eating period to 8 hours. Many people eat from 11 a.m. to 7 p.m. then fast the other 16 hours. This is the most popular method because you’re asleep for about half of the fasting period, and breakfast is the easiest meal to skip (for most people).
- The 5:2 Diet: Eat only 500 to 600 calories a day during two non-consecutive days a week. Eat normally the other 5 days.
- Eat-Stop-Eat: Fast 24 hours once or twice a week. This is easy to adapt for your schedule, but can be harder to sustain. An example would be eating dinner at 6 p.m. then not eating again until dinner the next day.
- Alternate-Day Fasting: Fast every other day. Some forms of this method allow for up to 500 calories on fasting days.
- The Warrior Diet: Fast during the day, then have a huge dinner. Small amounts of raw fruits and vegetables during the day are allowed.
- Spontaneous Meal Skipping: As the name suggests, this method of fasting involves skipping meals when you’re not hungry or are too busy to eat.
By limiting the hours you eat, the idea is that you’ll consume fewer calories and lose weight. Intermittent Fasting only works as a weight loss method if you don’t compensate by eating too many calories during the eating periods. It’s also critical that you eat healthy foods when you do eat. Binging on junk food after hours of fasting won’t do your health any good.
What are the benefits of Intermittent Fasting?
While weight loss is the most highly touted one, research shows IF offers many other health benefits.
- Increased metabolic rate: the combination of eating fewer total calories while burning calories at a faster rate can make IF an effective weight loss method 
- Increased levels of Human Growth Hormone (HGH): higher HGH levels can aid fat loss and enhance muscle gain 
- Lower levels of insulin: this makes stored body fat more accessible and may reduce the risk of Type 2 Diabetes 
- Enhanced cellular repair: this may offer anti-aging benefits and improve longevity [4, 5]
- Increased release of norepinephrine: this hormone aids in burning fat 
- May reduce inflammation 
- May reduce LDL cholesterol and other factors that contribute to heart disease 
- May help prevent cancer 
- May improve brain health and protect against Alzheimer’s Disease 
What are the risks of Intermittent Fasting?
For some people, Intermittent Fasting may not be beneficial, and could even be harmful. Consult your doctor prior to fasting if you:
- Have diabetes
- Have low blood pressure
- Take medication
- Are trying to conceive
- Are pregnant
- Are nursing
- Are underweight
- Have an eating disorder (or have had one in the past)
For most people, hunger and temporary feelings of weakness are the most common side effects.
What can I eat and drink while Intermittent Fasting?
Water, coffee, tea, and other non-caloric beverages are fine. Coffee can help suppress your appetite so is popular during fasts. Avoid adding sugar to your coffee. A little bit of heavy cream is okay. The general rule of thumb is to keep it under 50 calories.
May I take supplements while Intermittent Fasting?
It’s not only okay to take supplements, but it could also help you feel better. Exogenous ketones are an example of a supplement that can help during intermittent fasting. Here’s how they can help:
- Enhance weight loss. Ketone supplements in conjunction with a low-carb/high-fat (LCHF) diet, can help you achieve a state of ketosis, which can aid weight loss. It’s important to clarify that ketone supplements do not cause weight loss; instead, they cause your body to enter a state where it uses fat as its primary source of fuel. For those on a ketogenic diet, this usually translates to weight loss if the ratio of fat/protein/carb consumption is enough to induce ketosis.
- Provide energy and prevent lethargy. Another reason to take ketone supplements during fasting is that it can boost your energy levels when you’re feeling hungry or lethargic.
- Help suppress appetite. Lastly, ketone supplements can help with all those hunger pangs from fasting. It reduces your appetite and helps curb cravings.
Ketones have few calories, and are generally acceptable when fasting. Another common supplement while intermittent fasting is MCT oil or fats, like ghee or grass-fed butter.
Many people will drink keto “bulletproof” coffee with MCT oil, coconut oil, ghee or butter. Drinking boosted coffee promotes mental focus and satiety while still providing some of the benefits of fasting and ketosis. The term for this practice is called “fat fasting.”
Intermittent fasting is just one of many methods that can help you lose weight and lead a healthier life. Always remember that eating real (unprocessed) foods, staying hydrated, exercising regularly, and getting adequate sleep are the most important factors for health and wellness.