Does Intermittent Fasting Work Well With Keto?

The ketogenic diet is one where you restrict carbs and intermittent fasting is an eating pattern in which you restrict your food intake to certain hours of the day. If you're already on the keto diet, then combining it with intermittent fasting might give your body a powerful boost and help you enter the ketosis state.

If you’re looking to lose weight or simply keep fit, you might’ve tried many different diets. Keto fasting is the combination of two of the most popular modern diets — intermittent fasting and the keto diet. 

Read on to find out everything you need to know about intermittent fasting, the keto diet, whether they work well together, and more.

The ketogenic (keto) diet is named after a bodily process called ketosis. The intention when you are on this diet is to push your body into a long-term state of ketosis, which causes fat loss. 

Here’s a summary of how it works. Typically, the carbohydrates (especially sugars like glucose) that are obtained from food are the body's main energy source. On the keto diet, you try to change this by making fats the main source of energy for the body. This is done by reducing your dietary carb intake to the bare minimum and replacing carbs with lots of healthy fats and a moderate amount of protein.

The body then begins to use both dietary and stored fats as a source of fuel by breaking them down. This process of fat breakdown is called ketosis, which produces ketone bodies. During ketosis, ketone bodies will replace glucose as the primary source of energy. 

As your body maintains a ketosis state for longer periods, it can burn more fat, eventually resulting in weight loss. Thus, the keto diet is essentially a high-fat, moderate-protein, low-carb eating pattern.

What to eat on a keto diet

On the keto diet, you’re restricted to eating less than 50 grams of carbs per day. You have to minimize your intake of grains, cereals, starchy vegetables like potatoes, and fruits. 

Instead, your diet will mainly consist of healthy fats and proteins like high-fat meats, seafood, eggs, avocados, nuts, non-starchy veggies (preferably greens), and dairy products like butter, cheese, Greek yogurt, and cottage cheese.

Benefits of the keto diet

By placing your body in a state of nutritional ketosis, you can achieve many health benefits besides weight loss. These include:

• Decreased blood sugar levels and insulin resistance
• Improved neurological symptoms for conditions like epilepsy and Alzheimer’s
• Lowered triglyceride levels, which minimizes the risk of heart disease

How to get into ketosis

You can attain the ketosis state through two main routes. The first is diet, as described above. The second is fasting, which we’ll discuss next.

Intermittent fasting is not a diet in the sense of a prescribed set of foods. It is an eating pattern in which you restrict your food intake to certain hours of the day. Beyond those hours, you can’t consume anything of notable caloric value. For example, green tea is fine but coffee with milk and sugar is not.

Types of intermittent fasting

Intermittent fasting can involve restrictions affecting the time when you eat, the quantity of food that you eat, or both. Here are two of the most popular intermittent fasting types:

• 16:8. For this type, you’re allowed to eat anything you like but only for 8 hours in a day. You can’t eat for the remaining 16 hours of the day. For example, if you eat your first meal at noon, then you can’t eat from 8 pm until noon the next day.
• 5:2. For this type, you not only restrict when you eat but also how much you eat. You restrict yourself to eating only 400 to 600 calories per day for 2 days a week and then eat normally on the other 5 days. For example, you could eat normally from Monday to Friday and then fast on weekends.

How intermittent fasting works

During the fasting period, your body doesn’t have an external source of energy, so it’s forced to burn stored fat as its main source of fuel. This produces ketone bodies, pushing your body into a ketosis state. As long as the fasting state is maintained, the ketosis state is also maintained.

If you’re already on the keto diet, then combining the two might give your body a powerful boost and help you enter the ketosis state. Once you start keto, it usually takes the body around 2 to 3 weeks to switch from using carbs to fats as the primary energy source.

Meanwhile, during the intermittent fasting period, you’ll have low insulin levels and stored glycogen (sugars), so the body will have no choice but to opt for stored fat. Thus, even if you’ve never achieved an effective or longer-term ketosis state while on the keto diet, adding intermittent fasting to the mix is likely to give you better results.

Keto meals are designed to keep your body in ketosis even when you eat. Thus, all the beneficial effects of fasting are maintained even if you eat regularly. Therefore, the keto diet and intermittent fasting may have a complementary influence on your body's fat-burning ability.

This means that you may be able to achieve greater fat loss through keto fasting than you would through intermittent fasting or the keto diet alone. Intermittent fasting can boost your metabolism through thermogenesis (heat production), which forces your body to use up the fats that have been stored for a long time. 

You can also preserve muscle mass while losing weight through intermittent fasting, which is useful if you’re an athlete on a keto diet, and intermittent fasting similarly reduces hunger and increases satiety, which complements the keto diet since high-fat foods also have a high satiety value. 

So, you will probably eat less while still enjoying what you eat. This will prevent overeating and feelings of frustration or dissatisfaction, making you more likely to keep up with the diet.

Combining the keto diet with intermittent fasting is generally considered generally safe. However, if you’re pregnant, breastfeeding, or have a history of eating disorders, you may want to avoid this diet.

If you have any health conditions like diabetes or heart disease, you’re also advised to consult your health care provider before starting this diet since your blood sugar levels will be affected.

In some cases, people on this diet could experience side effects like irritability and fatigue.

Intermittent fasting is a great partner to the keto diet, but it’s not essential. Only try this diet if you feel physically and mentally prepared. If you find keto fasting too challenging, you may end up overeating on non-fasting days and undo all your hard work. 

If you can’t decide, try both methods separately first and then gradually combine the two as part of your healthy lifestyle. Don’t hesitate to contact your dietitian or medical practitioner for answers to any queries or concerns.